On 2024/10/22 12:05, Jeongjun Park wrote:
Hongbo Li <[email protected]> wrote:
On 2024/10/21 23:43, Jeongjun Park wrote:
The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
To fix this, we need to add validation on a.data_type in
alloc_lru_idx_fragmentation().
Reported-by: [email protected]
Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
Signed-off-by: Jeongjun Park <[email protected]>
---
fs/bcachefs/alloc_background.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
index f8e87c6721b1..163a67b97a40 100644
--- a/fs/bcachefs/alloc_background.h
+++ b/fs/bcachefs/alloc_background.h
@@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type
type)
static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
struct bch_dev *ca)
{
+ if (a.data_type >= BCH_DATA_NR)
+ return 0;
+
oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] UBSAN:
shift-out-of-bounds in bch2_alloc_to_text"). But in my humble opinion, the
validation changes also should be added. And in addition, move the condition about
a.data_type into data_type_movable will be better. Just my personal opinion.:)
[1] https://www.spinics.net/lists/kernel/msg5412619.html
I still disagree with the fix to make data_type_movable() do the validation,
but I think [1] is definitely a patch that needs to be added.
However, [1] is far from preventing the shift oob vulnerability described
in that syzbot report. Therefore, I think [1] should be written as a
standalone patch and committed, rather than as a patch for that
I'm fine for this.:)
Thanks,
Hongbo
syzbot report.
Thanks,
Hongbo
if (!data_type_movable(a.data_type) ||
!bch2_bucket_sectors_fragmented(ca, a))
return 0;
--
