On Wed, Oct 09, 2024 at 10:07:55PM GMT, 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 | 4 +++-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
> index 564841e5a24b..f6a02123144d 100644
> --- a/fs/bcachefs/ec.c
> +++ b/fs/bcachefs/ec.c
> @@ -114,6 +114,12 @@ 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))) {
> + bch_err_ratelimited(c, "stripe csum gran bits %u too big",
> + s->csum_granularity_bits);
> + return -BCH_ERR_stripe_csum_granularity_bits_too_big;
> + }
> +
that should be a bkey_fsck_err_on(), and you'll add to the enum in
sb-errors_format.h
> bkey_fsck_err_on(bkey_eq(k.k->p, POS_MIN) ||
> bpos_gt(k.k->p, POS(0, U32_MAX)),
> c, stripe_pos_bad,
> diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
> index 26990ad584d5..83659cdb93c8 100644
> --- a/fs/bcachefs/errcode.h
> +++ b/fs/bcachefs/errcode.h
> @@ -270,7 +270,9 @@
> x(BCH_ERR_nopromote, nopromote_enomem)
> \
> x(0, invalid_snapshot_node)
> \
> x(0, option_needs_open_fs)
> \
> - x(0, remove_disk_accounting_entry)
> + x(0, remove_disk_accounting_entry)
> \
> + x(EINVAL, stripe_csum_granularity_bits_too_big)
> +
>
> enum bch_errcode {
> BCH_ERR_START = 2048,
> --
> 2.43.0
>
