On 2024/10/9 17:10, Hongbo Li wrote: > > > On 2024/10/9 13:43, Zhao Mengmeng wrote: >> From: Zhao Mengmeng <[email protected]> >> >> syzbot report a shift-out-of-bounds issue: >> ------------[ cut here ]------------ >> UBSAN: shift-out-of-bounds in fs/bcachefs/ec.c:147:2 >> shift exponent 108 is too large for 32-bit type 'unsigned int' >> ---- >> Here s.csum_granularity_bits = 108, so shift is impossible for unsigned >> int. To fix, add a check in bch2_stripe_validate() to bail out, it has >> same checking logic with ec_stripe_key_init(). >> >> Reported-by: [email protected] >> Tested-by: [email protected] >> Closes: https://syzkaller.appspot.com/bug?extid=f8c98a50c323635be65d >> Suggested-by: Hongbo Li <[email protected]> >> Signed-off-by: Zhao Mengmeng <[email protected]> >> --- >> fs/bcachefs/ec.c | 6 ++++++ >> fs/bcachefs/errcode.h | 3 ++- >> 2 files changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c >> index 141a4c63142f..bc5ff1331c6f 100644 >> --- a/fs/bcachefs/ec.c >> +++ b/fs/bcachefs/ec.c >> @@ -113,6 +113,12 @@ int bch2_stripe_validate(struct bch_fs *c, struct >> bkey_s_c k, >> const struct bch_stripe *s = bkey_s_c_to_stripe(k).v; >> int ret = 0; >> + if (s->csum_granularity_bits >= ilog2(le16_to_cpu(s->sectors))) { > > csum_granularity_bits should do the left shift.
If use `1 << s->csum_granularity_bits(108)` to do the check, syzbot will still trigger shift-out-of bounds warning. So better check the bits directly.
