When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
issues may occur:
- z_erofs_pcluster_readmore() may take a long time to loop when the offset
is big enough, which is unnecessary.
- For example, it will loop 4691368 times and take about 27 seconds
with following case.
- offset = 19217289215
- inode_size = 1442672
- z_erofs_do_read_page() may loop infinitely due to the inappropriate
truncation in the below statement. Since the offset is 64 bits and
min_t() truncates the result to 32 bits. The solution is to replace
unsigned int with another 64-bit type, such as erofs_off_t.
cur = end - min_t(unsigned int, offset + end - map->m_la, end);
- For example:
- offset = 0x400160000
- end = 0x370
- map->m_la = 0x160370
- offset + end - map->m_la = 0x400000000
- offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
- Expected result:
- cur = 0
- Actual result:
- cur = 0x370
Signed-off-by: Chunhai Guo <[email protected]>
---
fs/erofs/zdata.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 5f1890e309c6..6abbd4510076 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -972,7 +972,8 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
struct erofs_map_blocks *const map = &fe->map;
const loff_t offset = page_offset(page);
bool tight = true, exclusive;
- unsigned int cur, end, spiltted;
+ erofs_off_t cur, end;
+ unsigned int spiltted;
int err = 0;
/* register locked file pages as online pages in pack */
@@ -1035,7 +1036,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
*/
tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
- cur = end - min_t(unsigned int, offset + end - map->m_la, end);
+ cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
if (!(map->m_flags & EROFS_MAP_MAPPED)) {
zero_user_segment(page, cur, end);
goto next_part;
@@ -1841,7 +1842,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
}
cur = map->m_la + map->m_llen - 1;
- while (cur >= end) {
+ while ((cur >= end) && (cur < i_size_read(inode))) {
pgoff_t index = cur >> PAGE_SHIFT;
struct page *page;
@@ -1876,6 +1877,12 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
trace_erofs_readpage(page, false);
f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
+ /* when trying to read beyond EOF, return zero page directly */
+ if (f.headoffset >= i_size_read(inode)) {
+ zero_user_segment(page, 0, PAGE_SIZE);
+ return 0;
+ }
+
z_erofs_pcluster_readmore(&f, NULL, true);
err = z_erofs_do_read_page(&f, page);
z_erofs_pcluster_readmore(&f, NULL, false);
--
2.25.1
Hi Chunhai,
On 2023/7/8 14:24, Chunhai Guo wrote:
> When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
> issues may occur:
> - z_erofs_pcluster_readmore() may take a long time to loop when the offset
> is big enough, which is unnecessary.
> - For example, it will loop 4691368 times and take about 27 seconds
> with following case.
> - offset = 19217289215
> - inode_size = 1442672
> - z_erofs_do_read_page() may loop infinitely due to the inappropriate
> truncation in the below statement. Since the offset is 64 bits and
> min_t() truncates the result to 32 bits. The solution is to replace
> unsigned int with another 64-bit type, such as erofs_off_t.
> cur = end - min_t(unsigned int, offset + end - map->m_la, end);
> - For example:
> - offset = 0x400160000
> - end = 0x370
> - map->m_la = 0x160370
> - offset + end - map->m_la = 0x400000000
> - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
Thanks for the catch!
Could you split these two into two patches?
how about using:
cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
for this?
since cur and end are all [0, PAGE_SIZE - 1] for now, and
folio_size() later.
> - Expected result:
> - cur = 0
> - Actual result:
> - cur = 0x370
>
> Signed-off-by: Chunhai Guo <[email protected]>
> ---
> fs/erofs/zdata.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 5f1890e309c6..6abbd4510076 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -972,7 +972,8 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
> struct erofs_map_blocks *const map = &fe->map;
> const loff_t offset = page_offset(page);
> bool tight = true, exclusive;
> - unsigned int cur, end, spiltted;
> + erofs_off_t cur, end;
> + unsigned int spiltted;
> int err = 0;
>
> /* register locked file pages as online pages in pack */
> @@ -1035,7 +1036,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
> */
> tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
>
> - cur = end - min_t(unsigned int, offset + end - map->m_la, end);
> + cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
> if (!(map->m_flags & EROFS_MAP_MAPPED)) {
> zero_user_segment(page, cur, end);
> goto next_part;
> @@ -1841,7 +1842,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
> }
>
> cur = map->m_la + map->m_llen - 1;
> - while (cur >= end) {
> + while ((cur >= end) && (cur < i_size_read(inode))) {
> pgoff_t index = cur >> PAGE_SHIFT;
> struct page *page;
>
> @@ -1876,6 +1877,12 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
> trace_erofs_readpage(page, false);
> f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
>
> + /* when trying to read beyond EOF, return zero page directly */
> + if (f.headoffset >= i_size_read(inode)) {
> + zero_user_segment(page, 0, PAGE_SIZE);
> + return 0;
> + }
Do we really need to optimize this rare case?
I guess the follow readmore fix is enough, thoughts?
Thanks,
Gao Xiang
On 2023/7/10 11:32, Chunhai Guo wrote:
> Hi Xiang,
>
> On 2023/7/8 17:00, Gao Xiang wrote:
>> Hi Chunhai,
>>
>> On 2023/7/8 14:24, Chunhai Guo wrote:
>>> When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
>>> issues may occur:
>>> - z_erofs_pcluster_readmore() may take a long time to loop when the offset
>>> is big enough, which is unnecessary.
>>> - For example, it will loop 4691368 times and take about 27 seconds
>>> with following case.
>>> - offset = 19217289215
>>> - inode_size = 1442672
>>> - z_erofs_do_read_page() may loop infinitely due to the inappropriate
>>> truncation in the below statement. Since the offset is 64 bits and
>>> min_t() truncates the result to 32 bits. The solution is to replace
>>> unsigned int with another 64-bit type, such as erofs_off_t.
>>> cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>>> - For example:
>>> - offset = 0x400160000
>>> - end = 0x370
>>> - map->m_la = 0x160370
>>> - offset + end - map->m_la = 0x400000000
>>> - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
>>
>> Thanks for the catch!
>>
>> Could you split these two into two patches?
>>
>> how about using:
>> cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
>> for this?
>>
>> since cur and end are all [0, PAGE_SIZE - 1] for now, and
>> folio_size() later.
>
> OK. I will split the patch.
>
> Sorry that I can not understand what is 'offend' refer to and what do you mean. Could you please describe it more clearly?
Sorry, there is a typo here, I meant 'offset'.
`cur` and `end` both are not exceed 4096 if your page_size
is 4096.
Does
cur = end - min_t(erofs_off_t, offset + end - map->m_la, end)
fix your issue?
>
>>> - Expected result:
>>> - cur = 0
>>> - Actual result:
>>> - cur = 0x370
>>>
>>> Signed-off-by: Chunhai Guo <[email protected]>
>>> ---
>>> fs/erofs/zdata.c | 13 ++++++++++---
>>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
>>> index 5f1890e309c6..6abbd4510076 100644
>>> --- a/fs/erofs/zdata.c
>>> +++ b/fs/erofs/zdata.c
>>> @@ -972,7 +972,8 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>>> struct erofs_map_blocks *const map = &fe->map;
>>> const loff_t offset = page_offset(page);
>>> bool tight = true, exclusive;
>>> - unsigned int cur, end, spiltted;
>>> + erofs_off_t cur, end;
>>> + unsigned int spiltted;
>>> int err = 0;
>>> /* register locked file pages as online pages in pack */
>>> @@ -1035,7 +1036,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>>> */
>>> tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
>>> - cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>>> + cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
>>> if (!(map->m_flags & EROFS_MAP_MAPPED)) {
>>> zero_user_segment(page, cur, end);
>>> goto next_part;
>>> @@ -1841,7 +1842,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
>>> }
>>> cur = map->m_la + map->m_llen - 1;
>>> - while (cur >= end) {
>>> + while ((cur >= end) && (cur < i_size_read(inode))) {
>>> pgoff_t index = cur >> PAGE_SHIFT;
>>> struct page *page;
>>> @@ -1876,6 +1877,12 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
>>> trace_erofs_readpage(page, false);
>>> f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
>>> + /* when trying to read beyond EOF, return zero page directly */
>>> + if (f.headoffset >= i_size_read(inode)) {
>>> + zero_user_segment(page, 0, PAGE_SIZE);
>>> + return 0;
>>> + }
>> Do we really need to optimize this rare case?
>> I guess the follow readmore fix is enough, thoughts? >
>> Thanks,
>> Gao Xiang
>
> Since the code is constantly being updated and someone may encounter this bug again, I think we had better fix it if possible.
z_erofs_do_read_page() already covers this case so I'm
not sure why we need to add another logic here.
Thanks,
Gao Xiang
>
> Thanks.
> Guo Chunhai
Hi Xiang,
On 2023/7/8 17:00, Gao Xiang wrote:
> Hi Chunhai,
>
> On 2023/7/8 14:24, Chunhai Guo wrote:
>> When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
>> issues may occur:
>> - z_erofs_pcluster_readmore() may take a long time to loop when the offset
>> is big enough, which is unnecessary.
>> - For example, it will loop 4691368 times and take about 27 seconds
>> with following case.
>> - offset = 19217289215
>> - inode_size = 1442672
>> - z_erofs_do_read_page() may loop infinitely due to the inappropriate
>> truncation in the below statement. Since the offset is 64 bits and
>> min_t() truncates the result to 32 bits. The solution is to replace
>> unsigned int with another 64-bit type, such as erofs_off_t.
>> cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>> - For example:
>> - offset = 0x400160000
>> - end = 0x370
>> - map->m_la = 0x160370
>> - offset + end - map->m_la = 0x400000000
>> - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
>
> Thanks for the catch!
>
> Could you split these two into two patches?
>
> how about using:
> cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
> for this?
>
> since cur and end are all [0, PAGE_SIZE - 1] for now, and
> folio_size() later.
OK. I will split the patch.
Sorry that I can not understand what is 'offend' refer to and what do
you mean. Could you please describe it more clearly?
>> - Expected result:
>> - cur = 0
>> - Actual result:
>> - cur = 0x370
>>
>> Signed-off-by: Chunhai Guo <[email protected]>
>> ---
>> fs/erofs/zdata.c | 13 ++++++++++---
>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
>> index 5f1890e309c6..6abbd4510076 100644
>> --- a/fs/erofs/zdata.c
>> +++ b/fs/erofs/zdata.c
>> @@ -972,7 +972,8 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>> struct erofs_map_blocks *const map = &fe->map;
>> const loff_t offset = page_offset(page);
>> bool tight = true, exclusive;
>> - unsigned int cur, end, spiltted;
>> + erofs_off_t cur, end;
>> + unsigned int spiltted;
>> int err = 0;
>>
>> /* register locked file pages as online pages in pack */
>> @@ -1035,7 +1036,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>> */
>> tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
>>
>> - cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>> + cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
>> if (!(map->m_flags & EROFS_MAP_MAPPED)) {
>> zero_user_segment(page, cur, end);
>> goto next_part;
>> @@ -1841,7 +1842,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
>> }
>>
>> cur = map->m_la + map->m_llen - 1;
>> - while (cur >= end) {
>> + while ((cur >= end) && (cur < i_size_read(inode))) {
>> pgoff_t index = cur >> PAGE_SHIFT;
>> struct page *page;
>>
>> @@ -1876,6 +1877,12 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
>> trace_erofs_readpage(page, false);
>> f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
>>
>> + /* when trying to read beyond EOF, return zero page directly */
>> + if (f.headoffset >= i_size_read(inode)) {
>> + zero_user_segment(page, 0, PAGE_SIZE);
>> + return 0;
>> + }
> Do we really need to optimize this rare case?
> I guess the follow readmore fix is enough, thoughts? >
> Thanks,
> Gao Xiang
Since the code is constantly being updated and someone may encounter
this bug again, I think we had better fix it if possible.
Thanks.
Guo Chunhai
On 2023/7/10 11:37, Gao Xiang wrote:
>
>
> On 2023/7/10 11:32, Chunhai Guo wrote:
>> Hi Xiang,
>>
>> On 2023/7/8 17:00, Gao Xiang wrote:
>>> Hi Chunhai,
>>>
>>> On 2023/7/8 14:24, Chunhai Guo wrote:
>>>> When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
>>>> issues may occur:
>>>> - z_erofs_pcluster_readmore() may take a long time to loop when the offset
>>>> is big enough, which is unnecessary.
>>>> - For example, it will loop 4691368 times and take about 27 seconds
>>>> with following case.
>>>> - offset = 19217289215
>>>> - inode_size = 1442672
>>>> - z_erofs_do_read_page() may loop infinitely due to the inappropriate
>>>> truncation in the below statement. Since the offset is 64 bits and
>>>> min_t() truncates the result to 32 bits. The solution is to replace
>>>> unsigned int with another 64-bit type, such as erofs_off_t.
>>>> cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>>>> - For example:
>>>> - offset = 0x400160000
>>>> - end = 0x370
>>>> - map->m_la = 0x160370
>>>> - offset + end - map->m_la = 0x400000000
>>>> - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
>>>
>>> Thanks for the catch!
>>>
>>> Could you split these two into two patches?
>>>
>>> how about using:
>>> cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
>>> for this?
>>>
>>> since cur and end are all [0, PAGE_SIZE - 1] for now, and
>>> folio_size() later.
>>
>> OK. I will split the patch.
>>
>> Sorry that I can not understand what is 'offend' refer to and what do you mean. Could you please describe it more clearly?
>
> Sorry, there is a typo here, I meant 'offset'.
>
> `cur` and `end` both are not exceed 4096 if your page_size
> is 4096.
>
> Does
> cur = end - min_t(erofs_off_t, offset + end - map->m_la, end)
>
> fix your issue?
Yes. I think this will fix this issue. Do you mean the below change is
unncessary?
>>>> - unsigned int cur, end, spiltted;
>>>> + erofs_off_t cur, end;
>>>> + unsigned int spiltted;
>
>>
>>>> - Expected result:
>>>> - cur = 0
>>>> - Actual result:
>>>> - cur = 0x370
>>>>
>>>> Signed-off-by: Chunhai Guo <[email protected]>
>>>> ---
>>>> fs/erofs/zdata.c | 13 ++++++++++---
>>>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
>>>> index 5f1890e309c6..6abbd4510076 100644
>>>> --- a/fs/erofs/zdata.c
>>>> +++ b/fs/erofs/zdata.c
>>>> @@ -972,7 +972,8 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>>>> struct erofs_map_blocks *const map = &fe->map;
>>>> const loff_t offset = page_offset(page);
>>>> bool tight = true, exclusive;
>>>> - unsigned int cur, end, spiltted;
>>>> + erofs_off_t cur, end;
>>>> + unsigned int spiltted;
>>>> int err = 0;
>>>> /* register locked file pages as online pages in pack */
>>>> @@ -1035,7 +1036,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>>>> */
>>>> tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
>>>> - cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>>>> + cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
>>>> if (!(map->m_flags & EROFS_MAP_MAPPED)) {
>>>> zero_user_segment(page, cur, end);
>>>> goto next_part;
>>>> @@ -1841,7 +1842,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
>>>> }
>>>> cur = map->m_la + map->m_llen - 1;
>>>> - while (cur >= end) {
>>>> + while ((cur >= end) && (cur < i_size_read(inode))) {
>>>> pgoff_t index = cur >> PAGE_SHIFT;
>>>> struct page *page;
>>>> @@ -1876,6 +1877,12 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
>>>> trace_erofs_readpage(page, false);
>>>> f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
>>>> + /* when trying to read beyond EOF, return zero page directly */
>>>> + if (f.headoffset >= i_size_read(inode)) {
>>>> + zero_user_segment(page, 0, PAGE_SIZE);
>>>> + return 0;
>>>> + }
>>> Do we really need to optimize this rare case?
>>> I guess the follow readmore fix is enough, thoughts? >
>>> Thanks,
>>> Gao Xiang
>>
>> Since the code is constantly being updated and someone may encounter this bug again, I think we had better fix it if possible.
>
> z_erofs_do_read_page() already covers this case so I'm
> not sure why we need to add another logic here.
You are right. I have removed this logic and sent the patch.
>
> Thanks,
> Gao Xiang
>
>>
>> Thanks.
>> Guo Chunhai
On 2023/7/10 12:35, Chunhai Guo wrote:
>
>
> On 2023/7/10 11:37, Gao Xiang wrote:
>>
>>
>> On 2023/7/10 11:32, Chunhai Guo wrote:
>>> Hi Xiang,
>>>
>>> On 2023/7/8 17:00, Gao Xiang wrote:
>>>> Hi Chunhai,
>>>>
>>>> On 2023/7/8 14:24, Chunhai Guo wrote:
>>>>> When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
>>>>> issues may occur:
>>>>> - z_erofs_pcluster_readmore() may take a long time to loop when the offset
>>>>> is big enough, which is unnecessary.
>>>>> - For example, it will loop 4691368 times and take about 27 seconds
>>>>> with following case.
>>>>> - offset = 19217289215
>>>>> - inode_size = 1442672
>>>>> - z_erofs_do_read_page() may loop infinitely due to the inappropriate
>>>>> truncation in the below statement. Since the offset is 64 bits and
>>>>> min_t() truncates the result to 32 bits. The solution is to replace
>>>>> unsigned int with another 64-bit type, such as erofs_off_t.
>>>>> cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>>>>> - For example:
>>>>> - offset = 0x400160000
>>>>> - end = 0x370
>>>>> - map->m_la = 0x160370
>>>>> - offset + end - map->m_la = 0x400000000
>>>>> - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
>>>>
>>>> Thanks for the catch!
>>>>
>>>> Could you split these two into two patches?
>>>>
>>>> how about using:
>>>> cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
>>>> for this?
>>>>
>>>> since cur and end are all [0, PAGE_SIZE - 1] for now, and
>>>> folio_size() later.
>>>
>>> OK. I will split the patch.
>>>
>>> Sorry that I can not understand what is 'offend' refer to and what do you mean. Could you please describe it more clearly?
>>
>> Sorry, there is a typo here, I meant 'offset'.
>>
>> `cur` and `end` both are not exceed 4096 if your page_size
>> is 4096.
>>
>> Does
>> cur = end - min_t(erofs_off_t, offset + end - map->m_la, end)
>>
>> fix your issue?
>
> Yes. I think this will fix this issue. Do you mean the below change is unncessary?
> >>>> - unsigned int cur, end, spiltted;
> >>>> + erofs_off_t cur, end;
> >>>> + unsigned int spiltted;
Yes, please help send a fix for this!
Thanks,
Gao Xiang
On 2023/7/10 13:02, Gao Xiang wrote:
>
>
> On 2023/7/10 12:35, Chunhai Guo wrote:
>>
>>
>> On 2023/7/10 11:37, Gao Xiang wrote:
>>>
>>>
>>> On 2023/7/10 11:32, Chunhai Guo wrote:
>>>> Hi Xiang,
>>>>
>>>> On 2023/7/8 17:00, Gao Xiang wrote:
>>>>> Hi Chunhai,
>>>>>
>>>>> On 2023/7/8 14:24, Chunhai Guo wrote:
>>>>>> When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
>>>>>> issues may occur:
>>>>>> - z_erofs_pcluster_readmore() may take a long time to loop when the offset
>>>>>> is big enough, which is unnecessary.
>>>>>> - For example, it will loop 4691368 times and take about 27 seconds
>>>>>> with following case.
>>>>>> - offset = 19217289215
>>>>>> - inode_size = 1442672
>>>>>> - z_erofs_do_read_page() may loop infinitely due to the inappropriate
>>>>>> truncation in the below statement. Since the offset is 64 bits and
>>>>>> min_t() truncates the result to 32 bits. The solution is to replace
>>>>>> unsigned int with another 64-bit type, such as erofs_off_t.
>>>>>> cur = end - min_t(unsigned int, offset + end - map->m_la, end);
>>>>>> - For example:
>>>>>> - offset = 0x400160000
>>>>>> - end = 0x370
>>>>>> - map->m_la = 0x160370
>>>>>> - offset + end - map->m_la = 0x400000000
>>>>>> - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
>>>>>
>>>>> Thanks for the catch!
>>>>>
>>>>> Could you split these two into two patches?
>>>>>
>>>>> how about using:
>>>>> cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
>>>>> for this?
>>>>>
>>>>> since cur and end are all [0, PAGE_SIZE - 1] for now, and
>>>>> folio_size() later.
>>>>
>>>> OK. I will split the patch.
>>>>
>>>> Sorry that I can not understand what is 'offend' refer to and what do you mean. Could you please describe it more clearly?
>>>
>>> Sorry, there is a typo here, I meant 'offset'.
>>>
>>> `cur` and `end` both are not exceed 4096 if your page_size
>>> is 4096.
>>>
>>> Does
>>> cur = end - min_t(erofs_off_t, offset + end - map->m_la, end)
>>>
>>> fix your issue?
>>
>> Yes. I think this will fix this issue. Do you mean the below change is unncessary?
>> >>>> - unsigned int cur, end, spiltted;
>> >>>> + erofs_off_t cur, end;
>> >>>> + unsigned int spiltted;
>
> Yes, please help send a fix for this!
>
> Thanks,
> Gao Xiang
>
Got it. I have sent the patch. Please have a check.
Thanks,
Guo Chunhai