Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
This was triggered by reproducer calling truncute with size 0,
which causes the following trace:
BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
Read of size 8 at addr ffff888115aa9508 by task syz-executor251/365
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
print_address_description+0x81/0x3c0 mm/kasan/report.c:233
__kasan_report mm/kasan/report.c:419 [inline]
kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
__exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
notify_change+0xb76/0xe10 fs/attr.c:336
do_truncate+0x1ea/0x2d0 fs/open.c:65
Add checks to validate if cluster number is within valid range in
exfat_clear_bitmap() and exfat_set_bitmap()
Cc: Namjae Jeon <[email protected]>
Cc: Sungjong Seo <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://syzkaller.appspot.com/bug?id=50381fc73821ecae743b8cf24b4c9a04776f767c
Reported-by: [email protected]
Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
Signed-off-by: Tadeusz Struk <[email protected]>
---
v2:
- Use is_valid_cluster() helper to validate clu
---
fs/exfat/balloc.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 03f142307174..92f5b5b5a0d0 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
struct exfat_sb_info *sbi = EXFAT_SB(sb);
WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+ if (!is_valid_cluster(sbi, clu))
+ return -EINVAL;
+
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
@@ -167,6 +170,9 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
struct exfat_mount_options *opts = &sbi->options;
WARN_ON(clu < EXFAT_FIRST_CLUSTER);
+ if (!is_valid_cluster(sbi, clu))
+ return;
+
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
--
2.36.1
> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
> This was triggered by reproducer calling truncute with size 0, which
> causes the following trace:
>
> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task syz-
> executor251/365
>
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline] dump_stack_lvl+0x1e2/0x24b
> lib/dump_stack.c:118
> print_address_description+0x81/0x3c0 mm/kasan/report.c:233
> __kasan_report mm/kasan/report.c:419 [inline]
> kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
> exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
> exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
> __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
> exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
> exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
> notify_change+0xb76/0xe10 fs/attr.c:336
> do_truncate+0x1ea/0x2d0 fs/open.c:65
>
> Add checks to validate if cluster number is within valid range in
> exfat_clear_bitmap() and exfat_set_bitmap()
>
> Cc: Namjae Jeon <[email protected]>
> Cc: Sungjong Seo <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
>
> Link: https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
> 21ecae743b8cf24b4c9a04776f767c
> Reported-by: [email protected]
> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
> Signed-off-by: Tadeusz Struk <[email protected]>
Looks good.
And it seems that WARN_ON() is no longer needed.
Reviewed-by: Sungjong Seo <[email protected]>
> ---
> v2:
> - Use is_valid_cluster() helper to validate clu
> ---
> fs/exfat/balloc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index
> 03f142307174..92f5b5b5a0d0 100644
> --- a/fs/exfat/balloc.c
> +++ b/fs/exfat/balloc.c
> @@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int
> clu, bool sync)
> struct exfat_sb_info *sbi = EXFAT_SB(sb);
>
> WARN_ON(clu < EXFAT_FIRST_CLUSTER);
> + if (!is_valid_cluster(sbi, clu))
> + return -EINVAL;
> +
> ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
> i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
> b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx); @@ -167,6 +170,9 @@
> void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
> struct exfat_mount_options *opts = &sbi->options;
>
> WARN_ON(clu < EXFAT_FIRST_CLUSTER);
> + if (!is_valid_cluster(sbi, clu))
> + return;
> +
> ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
> i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
> b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
> --
> 2.36.1
2022-05-16 23:51 GMT+09:00, Tadeusz Struk <[email protected]>:
> On 5/15/22 07:52, Sungjong Seo wrote:
>>> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
>>> This was triggered by reproducer calling truncute with size 0, which
>>> causes the following trace:
>>>
>>> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
>>> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task
>>> syz-
>>> executor251/365
>>>
>>> Call Trace:
>>> __dump_stack lib/dump_stack.c:77 [inline] dump_stack_lvl+0x1e2/0x24b
>>> lib/dump_stack.c:118
>>> print_address_description+0x81/0x3c0 mm/kasan/report.c:233
>>> __kasan_report mm/kasan/report.c:419 [inline]
>>> kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
>>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
>>> exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
>>> exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
>>> __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
>>> exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
>>> exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
>>> notify_change+0xb76/0xe10 fs/attr.c:336
>>> do_truncate+0x1ea/0x2d0 fs/open.c:65
>>>
>>> Add checks to validate if cluster number is within valid range in
>>> exfat_clear_bitmap() and exfat_set_bitmap()
>>>
>>> Cc: Namjae Jeon<[email protected]>
>>> Cc: Sungjong Seo<[email protected]>
>>> Cc:[email protected]
>>> Cc:[email protected]
>>> Cc:[email protected]
>>>
>>> Link:https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
>>> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
>>> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
>>> 21ecae743b8cf24b4c9a04776f767c
>>> Reported-by:[email protected]
>>> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
>>> Signed-off-by: Tadeusz Struk<[email protected]>
>> Looks good.
>> And it seems that WARN_ON() is no longer needed.
>
> Right. Do you want me to send a follow up patch that drops the WARN_ONs?
You don't need to do it. I have applied this patch to #exfat dev
branch after removing it.
Note that I have combined 1/2 into 2/2 patch.
Thanks!
>
>> Reviewed-by: Sungjong Seo<[email protected]>
>>
>
> Thank you.
>
> --
> Thanks,
> Tadeusz
>
On 5/16/22 16:31, Namjae Jeon wrote:
>>> Looks good.
>>> And it seems that WARN_ON() is no longer needed.
>> Right. Do you want me to send a follow up patch that drops the WARN_ONs?
> You don't need to do it. I have applied this patch to #exfat dev
> branch after removing it.
> Note that I have combined 1/2 into 2/2 patch.
> Thanks!
That's fine with me. Thanks for taking it.
--
Thanks,
Tadeusz
On 5/15/22 07:52, Sungjong Seo wrote:
>> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
>> This was triggered by reproducer calling truncute with size 0, which
>> causes the following trace:
>>
>> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
>> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task syz-
>> executor251/365
>>
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline] dump_stack_lvl+0x1e2/0x24b
>> lib/dump_stack.c:118
>> print_address_description+0x81/0x3c0 mm/kasan/report.c:233
>> __kasan_report mm/kasan/report.c:419 [inline]
>> kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
>> exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
>> exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
>> __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
>> exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
>> exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
>> notify_change+0xb76/0xe10 fs/attr.c:336
>> do_truncate+0x1ea/0x2d0 fs/open.c:65
>>
>> Add checks to validate if cluster number is within valid range in
>> exfat_clear_bitmap() and exfat_set_bitmap()
>>
>> Cc: Namjae Jeon<[email protected]>
>> Cc: Sungjong Seo<[email protected]>
>> Cc:[email protected]
>> Cc:[email protected]
>> Cc:[email protected]
>>
>> Link:https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
>> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
>> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
>> 21ecae743b8cf24b4c9a04776f767c
>> Reported-by:[email protected]
>> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
>> Signed-off-by: Tadeusz Struk<[email protected]>
> Looks good.
> And it seems that WARN_ON() is no longer needed.
Right. Do you want me to send a follow up patch that drops the WARN_ONs?
> Reviewed-by: Sungjong Seo<[email protected]>
>
Thank you.
--
Thanks,
Tadeusz