Bug description and fix:
1. Write data to a file, say all 1s from offset 0 to 16.
2. Truncate the file to a smaller size, say 8 bytes.
3. Write new bytes (say 2s) from an offset past the original size of the
file, say at offset 20, for 4 bytes. This is supposed to create a "hole"
in the file, meaning that the bytes from offset 8 (where it was truncated
above) up to the new write at offset 20, should all be 0s (zeros).
4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount
and remount) the f/s.
5. Check the content of the file. It is wrong. The 1s that used to be
between bytes 9 and 16, before the truncation, have REAPPEARED (they should
be 0s).
We wrote a script and helper C program to reproduce the bug
(reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can
make them available to anyone.
The above example is shown when writing a small file within the same first
page. But the bug happens for larger files, as long as steps 1, 2, and 3
above all happen within the same page.
The problem was traced to the jffs2_write_begin code, where it goes into an
'if' statement intended to handle writes past the current EOF (i.e., writes
that may create a hole). The code computes a 'pageofs' that is the floor
of the write position (pos), aligned to the page size boundary. In other
words, 'pageofs' will never be larger than 'pos'. The code then sets the
internal jffs2_raw_inode->isize to the size of max(current inode size,
pageofs) but that is wrong: the new file size should be the 'pos', which is
larger than both the current inode size and pageofs.
Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to
the difference between the pageofs minus current inode size; instead it
should be the current pos minus the current inode size. Finally,
inode->i_size was also set incorrectly.
The patch below fixes this bug. The bug was discovered using a new tool
for finding f/s bugs using model checking, called MCFS (Model Checking File
Systems).
Signed-off-by: Yifei Liu <[email protected]>
Signed-off-by: Erez Zadok <[email protected]>
Signed-off-by: Manish Adkar <[email protected]>
---
fs/jffs2/file.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
index ba86acbe12d3..0479096b96e4 100644
--- a/fs/jffs2/file.c
+++ b/fs/jffs2/file.c
@@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
pgoff_t index = pos >> PAGE_SHIFT;
- uint32_t pageofs = index << PAGE_SHIFT;
int ret = 0;
jffs2_dbg(1, "%s()\n", __func__);
- if (pageofs > inode->i_size) {
- /* Make new hole frag from old EOF to new page */
+ if (pos > inode->i_size) {
+ /* Make new hole frag from old EOF to new position */
struct jffs2_raw_inode ri;
struct jffs2_full_dnode *fn;
uint32_t alloc_len;
- jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
- (unsigned int)inode->i_size, pageofs);
+ jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
+ (unsigned int)inode->i_size, (uint32_t)pos);
ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
@@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
ri.mode = cpu_to_jemode(inode->i_mode);
ri.uid = cpu_to_je16(i_uid_read(inode));
ri.gid = cpu_to_je16(i_gid_read(inode));
- ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
+ ri.isize = cpu_to_je32((uint32_t)pos);
ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
ri.offset = cpu_to_je32(inode->i_size);
- ri.dsize = cpu_to_je32(pageofs - inode->i_size);
+ ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
ri.csize = cpu_to_je32(0);
ri.compr = JFFS2_COMPR_ZERO;
ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
@@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
goto out_err;
}
jffs2_complete_reservation(c);
- inode->i_size = pageofs;
+ inode->i_size = pos;
mutex_unlock(&f->sem);
}
--
2.25.1
????????????????????????????????????????????????????????????????????????☺️☺️☺️☺️☺️????????????????????????????????????????????????????????☺️☺️☺️????????????????????????☺️☺️????????????☺️????????????☺️☺️????????????????☺️☺️????
Sent from my iPhon✌️
> On Jul 25, 2022, at 1:01 AM, Yifei Liu <[email protected]> wrote:
>
> Bug description and fix:
>
> 1. Write data to a file, say all 1s from offset 0 to 16.
>
> 2. Truncate the file to a smaller size, say 8 bytes.
>
> 3. Write new bytes (say 2s) from an offset past the original size of the
> file, say at offset 20, for 4 bytes. This is supposed to create a "hole"
> in the file, meaning that the bytes from offset 8 (where it was truncated
> above) up to the new write at offset 20, should all be 0s (zeros).
>
> 4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount
> and remount) the f/s.
>
> 5. Check the content of the file. It is wrong. The 1s that used to be
> between bytes 9 and 16, before the truncation, have REAPPEARED (they should
> be 0s).
>
> We wrote a script and helper C program to reproduce the bug
> (reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can
> make them available to anyone.
>
> The above example is shown when writing a small file within the same first
> page. But the bug happens for larger files, as long as steps 1, 2, and 3
> above all happen within the same page.
>
> The problem was traced to the jffs2_write_begin code, where it goes into an
> 'if' statement intended to handle writes past the current EOF (i.e., writes
> that may create a hole). The code computes a 'pageofs' that is the floor
> of the write position (pos), aligned to the page size boundary. In other
> words, 'pageofs' will never be larger than 'pos'. The code then sets the
> internal jffs2_raw_inode->isize to the size of max(current inode size,
> pageofs) but that is wrong: the new file size should be the 'pos', which is
> larger than both the current inode size and pageofs.
>
> Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to
> the difference between the pageofs minus current inode size; instead it
> should be the current pos minus the current inode size. Finally,
> inode->i_size was also set incorrectly.
>
> The patch below fixes this bug. The bug was discovered using a new tool
> for finding f/s bugs using model checking, called MCFS (Model Checking File
> Systems).
>
> Signed-off-by: Yifei Liu <[email protected]>
> Signed-off-by: Erez Zadok <[email protected]>
> Signed-off-by: Manish Adkar <[email protected]>
> ---
> fs/jffs2/file.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
> index ba86acbe12d3..0479096b96e4 100644
> --- a/fs/jffs2/file.c
> +++ b/fs/jffs2/file.c
> @@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
> struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
> struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
> pgoff_t index = pos >> PAGE_SHIFT;
> - uint32_t pageofs = index << PAGE_SHIFT;
> int ret = 0;
>
> jffs2_dbg(1, "%s()\n", __func__);
>
> - if (pageofs > inode->i_size) {
> - /* Make new hole frag from old EOF to new page */
> + if (pos > inode->i_size) {
> + /* Make new hole frag from old EOF to new position */
> struct jffs2_raw_inode ri;
> struct jffs2_full_dnode *fn;
> uint32_t alloc_len;
>
> - jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
> - (unsigned int)inode->i_size, pageofs);
> + jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
> + (unsigned int)inode->i_size, (uint32_t)pos);
>
> ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
> ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
> @@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
> ri.mode = cpu_to_jemode(inode->i_mode);
> ri.uid = cpu_to_je16(i_uid_read(inode));
> ri.gid = cpu_to_je16(i_gid_read(inode));
> - ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
> + ri.isize = cpu_to_je32((uint32_t)pos);
> ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
> ri.offset = cpu_to_je32(inode->i_size);
> - ri.dsize = cpu_to_je32(pageofs - inode->i_size);
> + ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
> ri.csize = cpu_to_je32(0);
> ri.compr = JFFS2_COMPR_ZERO;
> ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
> @@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
> goto out_err;
> }
> jffs2_complete_reservation(c);
> - inode->i_size = pageofs;
> + inode->i_size = pos;
> mutex_unlock(&f->sem);
> }
>
> --
> 2.25.1
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
Koop????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????️????????????????????????️????????????????????????????????????
Ooiggvklpoure????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☠️????????????????????????????????????????????????????????????????☠️☠️☠️☠️
Sent from my iPhone
> On Jul 25, 2022, at 1:04 AM, Vanessa Page <[email protected]> wrote:
>
> ????????????????????????????????????????????????????????????????????????☺️☺️☺️☺️☺️????????????????????????????????????????????????????????☺️☺️☺️????????????????????????☺️☺️????????????☺️????????????☺️☺️????????????????☺️☺️????
>
> Sent from my iPhon✌️
>
>> On Jul 25, 2022, at 1:01 AM, Yifei Liu <[email protected]> wrote:
>>
>> Bug description and fix:
>>
>> 1. Write data to a file, say all 1s from offset 0 to 16.
>>
>> 2. Truncate the file to a smaller size, say 8 bytes.
>>
>> 3. Write new bytes (say 2s) from an offset past the original size of the
>> file, say at offset 20, for 4 bytes. This is supposed to create a "hole"
>> in the file, meaning that the bytes from offset 8 (where it was truncated
>> above) up to the new write at offset 20, should all be 0s (zeros).
>>
>> 4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount
>> and remount) the f/s.
>>
>> 5. Check the content of the file. It is wrong. The 1s that used to be
>> between bytes 9 and 16, before the truncation, have REAPPEARED (they should
>> be 0s).
>>
>> We wrote a script and helper C program to reproduce the bug
>> (reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can
>> make them available to anyone.
>>
>> The above example is shown when writing a small file within the same first
>> page. But the bug happens for larger files, as long as steps 1, 2, and 3
>> above all happen within the same page.
>>
>> The problem was traced to the jffs2_write_begin code, where it goes into an
>> 'if' statement intended to handle writes past the current EOF (i.e., writes
>> that may create a hole). The code computes a 'pageofs' that is the floor
>> of the write position (pos), aligned to the page size boundary. In other
>> words, 'pageofs' will never be larger than 'pos'. The code then sets the
>> internal jffs2_raw_inode->isize to the size of max(current inode size,
>> pageofs) but that is wrong: the new file size should be the 'pos', which is
>> larger than both the current inode size and pageofs.
>>
>> Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to
>> the difference between the pageofs minus current inode size; instead it
>> should be the current pos minus the current inode size. Finally,
>> inode->i_size was also set incorrectly.
>>
>> The patch below fixes this bug. The bug was discovered using a new tool
>> for finding f/s bugs using model checking, called MCFS (Model Checking File
>> Systems).
>>
>> Signed-off-by: Yifei Liu <[email protected]>
>> Signed-off-by: Erez Zadok <[email protected]>
>> Signed-off-by: Manish Adkar <[email protected]>
>> ---
>> fs/jffs2/file.c | 15 +++++++--------
>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
>> index ba86acbe12d3..0479096b96e4 100644
>> --- a/fs/jffs2/file.c
>> +++ b/fs/jffs2/file.c
>> @@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
>> struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
>> pgoff_t index = pos >> PAGE_SHIFT;
>> - uint32_t pageofs = index << PAGE_SHIFT;
>> int ret = 0;
>>
>> jffs2_dbg(1, "%s()\n", __func__);
>>
>> - if (pageofs > inode->i_size) {
>> - /* Make new hole frag from old EOF to new page */
>> + if (pos > inode->i_size) {
>> + /* Make new hole frag from old EOF to new position */
>> struct jffs2_raw_inode ri;
>> struct jffs2_full_dnode *fn;
>> uint32_t alloc_len;
>>
>> - jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
>> - (unsigned int)inode->i_size, pageofs);
>> + jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
>> + (unsigned int)inode->i_size, (uint32_t)pos);
>>
>> ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
>> ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
>> @@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> ri.mode = cpu_to_jemode(inode->i_mode);
>> ri.uid = cpu_to_je16(i_uid_read(inode));
>> ri.gid = cpu_to_je16(i_gid_read(inode));
>> - ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
>> + ri.isize = cpu_to_je32((uint32_t)pos);
>> ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
>> ri.offset = cpu_to_je32(inode->i_size);
>> - ri.dsize = cpu_to_je32(pageofs - inode->i_size);
>> + ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
>> ri.csize = cpu_to_je32(0);
>> ri.compr = JFFS2_COMPR_ZERO;
>> ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
>> @@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> goto out_err;
>> }
>> jffs2_complete_reservation(c);
>> - inode->i_size = pageofs;
>> + inode->i_size = pos;
>> mutex_unlock(&f->sem);
>> }
>>
>> --
>> 2.25.1
>>
>>
>> ______________________________________________________
>> Linux MTD discussion mailing list
>> http://lists.infradead.org/mailman/listinfo/linux-mtd/
You lame ass stalking motherfucker. You are committing a crime and I have reported you to the police.
Koop????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????️????????????????????????️????????????????????????????????????
Ooiggvklpoure????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☠️????????????????????????????????????????????????????????????????☠️☠️☠️☠️
> On Jul 25, 2022, at 1:04 AM, Vanessa Page <[email protected]> wrote:
>
> ????????????????????????????????????????????????????????????????????????☺️☺️☺️☺️☺️????????????????????????????????????????????????????????☺️☺️☺️????????????????????????☺️☺️????????????☺️????????????☺️☺️????????????????☺️☺️????
>
> Sent from my iPhon✌️
>
>> On Jul 25, 2022, at 1:01 AM, Yifei Liu <[email protected]> wrote:
>>
>> Bug description and fix:
>>
>> 1. Write data to a file, say all 1s from offset 0 to 16.
>>
>> 2. Truncate the file to a smaller size, say 8 bytes.
>>
>> 3. Write new bytes (say 2s) from an offset past the original size of the
>> file, say at offset 20, for 4 bytes. This is supposed to create a "hole"
>> in the file, meaning that the bytes from offset 8 (where it was truncated
>> above) up to the new write at offset 20, should all be 0s (zeros).
>>
>> 4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount
>> and remount) the f/s.
>>
>> 5. Check the content of the file. It is wrong. The 1s that used to be
>> between bytes 9 and 16, before the truncation, have REAPPEARED (they should
>> be 0s).
>>
>> We wrote a script and helper C program to reproduce the bug
>> (reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can
>> make them available to anyone.
>>
>> The above example is shown when writing a small file within the same first
>> page. But the bug happens for larger files, as long as steps 1, 2, and 3
>> above all happen within the same page.
>>
>> The problem was traced to the jffs2_write_begin code, where it goes into an
>> 'if' statement intended to handle writes past the current EOF (i.e., writes
>> that may create a hole). The code computes a 'pageofs' that is the floor
>> of the write position (pos), aligned to the page size boundary. In other
>> words, 'pageofs' will never be larger than 'pos'. The code then sets the
>> internal jffs2_raw_inode->isize to the size of max(current inode size,
>> pageofs) but that is wrong: the new file size should be the 'pos', which is
>> larger than both the current inode size and pageofs.
>>
>> Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to
>> the difference between the pageofs minus current inode size; instead it
>> should be the current pos minus the current inode size. Finally,
>> inode->i_size was also set incorrectly.
>>
>> The patch below fixes this bug. The bug was discovered using a new tool
>> for finding f/s bugs using model checking, called MCFS (Model Checking File
>> Systems).
>>
>> Signed-off-by: Yifei Liu <[email protected]>
>> Signed-off-by: Erez Zadok <[email protected]>
>> Signed-off-by: Manish Adkar <[email protected]>
>> ---
>> fs/jffs2/file.c | 15 +++++++--------
>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
>> index ba86acbe12d3..0479096b96e4 100644
>> --- a/fs/jffs2/file.c
>> +++ b/fs/jffs2/file.c
>> @@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
>> struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
>> pgoff_t index = pos >> PAGE_SHIFT;
>> - uint32_t pageofs = index << PAGE_SHIFT;
>> int ret = 0;
>>
>> jffs2_dbg(1, "%s()\n", __func__);
>>
>> - if (pageofs > inode->i_size) {
>> - /* Make new hole frag from old EOF to new page */
>> + if (pos > inode->i_size) {
>> + /* Make new hole frag from old EOF to new position */
>> struct jffs2_raw_inode ri;
>> struct jffs2_full_dnode *fn;
>> uint32_t alloc_len;
>>
>> - jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
>> - (unsigned int)inode->i_size, pageofs);
>> + jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
>> + (unsigned int)inode->i_size, (uint32_t)pos);
>>
>> ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
>> ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
>> @@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> ri.mode = cpu_to_jemode(inode->i_mode);
>> ri.uid = cpu_to_je16(i_uid_read(inode));
>> ri.gid = cpu_to_je16(i_gid_read(inode));
>> - ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
>> + ri.isize = cpu_to_je32((uint32_t)pos);
>> ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
>> ri.offset = cpu_to_je32(inode->i_size);
>> - ri.dsize = cpu_to_je32(pageofs - inode->i_size);
>> + ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
>> ri.csize = cpu_to_je32(0);
>> ri.compr = JFFS2_COMPR_ZERO;
>> ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
>> @@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> goto out_err;
>> }
>> jffs2_complete_reservation(c);
>> - inode->i_size = pageofs;
>> + inode->i_size = pos;
>> mutex_unlock(&f->sem);
>> }
>>
>> --
>> 2.25.1
>>
>>
>> ______________________________________________________
>> Linux MTD discussion mailing list
>> http://lists.infradead.org/mailman/listinfo/linux-mtd/
Koop????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????️????????????????????????️????????????????????????????????????
Ooiggvklpoure????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☠️????????????????????????????????????????????????????????????????☠️☠️☠️☠️
Sent from my iPhone
> On Jul 25, 2022, at 5:37 PM, Vanessa Page <[email protected]> wrote:
>
> Koop????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????️????????????????????????️????????????????????????????????????
> Ooiggvklpoure????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☠️????????????????????????????????????????????????????????????????☠️☠️☠️☠️
Koop????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????️????????????????????????️????????????????????????????????????
Ooiggvklpoure????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☠️????????????????????????????????????????????????????????????????☠️☠️☠️☠️
> On Jul 25, 2022, at 1:06 AM, Vanessa Page <[email protected]> wrote:
>
> ????????????????????????????????????????????????????????????????????????☺️☺️☺️☺️☺️????????????????????????????????????????????????????????☺️☺️☺️????????????????????????☺️☺️????????????☺️????????????☺️☺️????????????????☺️☺️????
>
> Sent from my iPhon✌️
>
>> On Jul 25, 2022, at 1:01 AM, Yifei Liu <[email protected]> wrote:
>>
>> Bug description and fix:
>>
>> 1. Write data to a file, say all 1s from offset 0 to 16.
>>
>> 2. Truncate the file to a smaller size, say 8 bytes.
>>
>> 3. Write new bytes (say 2s) from an offset past the original size of the
>> file, say at offset 20, for 4 bytes. This is supposed to create a "hole"
>> in the file, meaning that the bytes from offset 8 (where it was truncated
>> above) up to the new write at offset 20, should all be 0s (zeros).
>>
>> 4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount
>> and remount) the f/s.
>>
>> 5. Check the content of the file. It is wrong. The 1s that used to be
>> between bytes 9 and 16, before the truncation, have REAPPEARED (they should
>> be 0s).
>>
>> We wrote a script and helper C program to reproduce the bug
>> (reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can
>> make them available to anyone.
>>
>> The above example is shown when writing a small file within the same first
>> page. But the bug happens for larger files, as long as steps 1, 2, and 3
>> above all happen within the same page.
>>
>> The problem was traced to the jffs2_write_begin code, where it goes into an
>> 'if' statement intended to handle writes past the current EOF (i.e., writes
>> that may create a hole). The code computes a 'pageofs' that is the floor
>> of the write position (pos), aligned to the page size boundary. In other
>> words, 'pageofs' will never be larger than 'pos'. The code then sets the
>> internal jffs2_raw_inode->isize to the size of max(current inode size,
>> pageofs) but that is wrong: the new file size should be the 'pos', which is
>> larger than both the current inode size and pageofs.
>>
>> Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to
>> the difference between the pageofs minus current inode size; instead it
>> should be the current pos minus the current inode size. Finally,
>> inode->i_size was also set incorrectly.
>>
>> The patch below fixes this bug. The bug was discovered using a new tool
>> for finding f/s bugs using model checking, called MCFS (Model Checking File
>> Systems).
>>
>> Signed-off-by: Yifei Liu <[email protected]>
>> Signed-off-by: Erez Zadok <[email protected]>
>> Signed-off-by: Manish Adkar <[email protected]>
>> ---
>> fs/jffs2/file.c | 15 +++++++--------
>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
>> index ba86acbe12d3..0479096b96e4 100644
>> --- a/fs/jffs2/file.c
>> +++ b/fs/jffs2/file.c
>> @@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
>> struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
>> pgoff_t index = pos >> PAGE_SHIFT;
>> - uint32_t pageofs = index << PAGE_SHIFT;
>> int ret = 0;
>>
>> jffs2_dbg(1, "%s()\n", __func__);
>>
>> - if (pageofs > inode->i_size) {
>> - /* Make new hole frag from old EOF to new page */
>> + if (pos > inode->i_size) {
>> + /* Make new hole frag from old EOF to new position */
>> struct jffs2_raw_inode ri;
>> struct jffs2_full_dnode *fn;
>> uint32_t alloc_len;
>>
>> - jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
>> - (unsigned int)inode->i_size, pageofs);
>> + jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
>> + (unsigned int)inode->i_size, (uint32_t)pos);
>>
>> ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
>> ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
>> @@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> ri.mode = cpu_to_jemode(inode->i_mode);
>> ri.uid = cpu_to_je16(i_uid_read(inode));
>> ri.gid = cpu_to_je16(i_gid_read(inode));
>> - ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
>> + ri.isize = cpu_to_je32((uint32_t)pos);
>> ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
>> ri.offset = cpu_to_je32(inode->i_size);
>> - ri.dsize = cpu_to_je32(pageofs - inode->i_size);
>> + ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
>> ri.csize = cpu_to_je32(0);
>> ri.compr = JFFS2_COMPR_ZERO;
>> ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
>> @@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>> goto out_err;
>> }
>> jffs2_complete_reservation(c);
>> - inode->i_size = pageofs;
>> + inode->i_size = pos;
>> mutex_unlock(&f->sem);
>> }
>>
>> --
>> 2.25.1
>>
>>
>> ______________________________________________________
>> Linux MTD discussion mailing list
>> http://lists.infradead.org/mailman/listinfo/linux-mtd/
Stop fucking emailing me you suck fuck. You want a password so you can hack my shit you broke motherfucker
People are not THAT stupid.
> On Jul 25, 2022, at 6:11 PM, Vanessa Page <[email protected]> wrote:
>
> You lame ass stalking motherfucker. You are committing a crime and I have reported you to the police.
>
> Koop????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????️????????????????????????️????????????????????????????????????
> Ooiggvklpoure????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☹️????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????☠️????????????????????????????????????????????????????????????????☠️☠️☠️☠️
>
>> On Jul 25, 2022, at 1:04 AM, Vanessa Page <[email protected]> wrote:
>>
>> ????????????????????????????????????????????????????????????????????????☺️☺️☺️☺️☺️????????????????????????????????????????????????????????☺️☺️☺️????????????????????????☺️☺️????????????☺️????????????☺️☺️????????????????☺️☺️????
>>
>> Sent from my iPhon✌️
>>
>>>> On Jul 25, 2022, at 1:01 AM, Yifei Liu <[email protected]> wrote:
>>>
>>> Bug description and fix:
>>>
>>> 1. Write data to a file, say all 1s from offset 0 to 16.
>>>
>>> 2. Truncate the file to a smaller size, say 8 bytes.
>>>
>>> 3. Write new bytes (say 2s) from an offset past the original size of the
>>> file, say at offset 20, for 4 bytes. This is supposed to create a "hole"
>>> in the file, meaning that the bytes from offset 8 (where it was truncated
>>> above) up to the new write at offset 20, should all be 0s (zeros).
>>>
>>> 4. flush all caches using "echo 3 > /proc/sys/vm/drop_caches" (or unmount
>>> and remount) the f/s.
>>>
>>> 5. Check the content of the file. It is wrong. The 1s that used to be
>>> between bytes 9 and 16, before the truncation, have REAPPEARED (they should
>>> be 0s).
>>>
>>> We wrote a script and helper C program to reproduce the bug
>>> (reproduce_jffs2_write_begin_issue.sh, write_file.c, and Makefile). We can
>>> make them available to anyone.
>>>
>>> The above example is shown when writing a small file within the same first
>>> page. But the bug happens for larger files, as long as steps 1, 2, and 3
>>> above all happen within the same page.
>>>
>>> The problem was traced to the jffs2_write_begin code, where it goes into an
>>> 'if' statement intended to handle writes past the current EOF (i.e., writes
>>> that may create a hole). The code computes a 'pageofs' that is the floor
>>> of the write position (pos), aligned to the page size boundary. In other
>>> words, 'pageofs' will never be larger than 'pos'. The code then sets the
>>> internal jffs2_raw_inode->isize to the size of max(current inode size,
>>> pageofs) but that is wrong: the new file size should be the 'pos', which is
>>> larger than both the current inode size and pageofs.
>>>
>>> Similarly, the code incorrectly sets the internal jffs2_raw_inode->dsize to
>>> the difference between the pageofs minus current inode size; instead it
>>> should be the current pos minus the current inode size. Finally,
>>> inode->i_size was also set incorrectly.
>>>
>>> The patch below fixes this bug. The bug was discovered using a new tool
>>> for finding f/s bugs using model checking, called MCFS (Model Checking File
>>> Systems).
>>>
>>> Signed-off-by: Yifei Liu <[email protected]>
>>> Signed-off-by: Erez Zadok <[email protected]>
>>> Signed-off-by: Manish Adkar <[email protected]>
>>> ---
>>> fs/jffs2/file.c | 15 +++++++--------
>>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
>>> index ba86acbe12d3..0479096b96e4 100644
>>> --- a/fs/jffs2/file.c
>>> +++ b/fs/jffs2/file.c
>>> @@ -137,19 +137,18 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>>> struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
>>> struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
>>> pgoff_t index = pos >> PAGE_SHIFT;
>>> - uint32_t pageofs = index << PAGE_SHIFT;
>>> int ret = 0;
>>>
>>> jffs2_dbg(1, "%s()\n", __func__);
>>>
>>> - if (pageofs > inode->i_size) {
>>> - /* Make new hole frag from old EOF to new page */
>>> + if (pos > inode->i_size) {
>>> + /* Make new hole frag from old EOF to new position */
>>> struct jffs2_raw_inode ri;
>>> struct jffs2_full_dnode *fn;
>>> uint32_t alloc_len;
>>>
>>> - jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
>>> - (unsigned int)inode->i_size, pageofs);
>>> + jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
>>> + (unsigned int)inode->i_size, (uint32_t)pos);
>>>
>>> ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
>>> ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
>>> @@ -169,10 +168,10 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>>> ri.mode = cpu_to_jemode(inode->i_mode);
>>> ri.uid = cpu_to_je16(i_uid_read(inode));
>>> ri.gid = cpu_to_je16(i_gid_read(inode));
>>> - ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
>>> + ri.isize = cpu_to_je32((uint32_t)pos);
>>> ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
>>> ri.offset = cpu_to_je32(inode->i_size);
>>> - ri.dsize = cpu_to_je32(pageofs - inode->i_size);
>>> + ri.dsize = cpu_to_je32((uint32_t)pos - inode->i_size);
>>> ri.csize = cpu_to_je32(0);
>>> ri.compr = JFFS2_COMPR_ZERO;
>>> ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
>>> @@ -202,7 +201,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
>>> goto out_err;
>>> }
>>> jffs2_complete_reservation(c);
>>> - inode->i_size = pageofs;
>>> + inode->i_size = pos;
>>> mutex_unlock(&f->sem);
>>> }
>>>
>>> --
>>> 2.25.1
>>>
>>>
>>> ______________________________________________________
>>> Linux MTD discussion mailing list
>>> http://lists.infradead.org/mailman/listinfo/linux-mtd/