On Wed, Oct 23, 2024 at 11:30:44PM +0200, Gianfranco Trad wrote:
> Add check on layout->sb_max_size_bits against BCH_SB_LAYOUT_SIZE_BITS_MAX
> to prevent UBSAN shift-out-of-bounds in validate_sb_layout().
>
> Reported-by: [email protected]
> Closes: https://syzkaller.appspot.com/bug?extid=089fad5a3a5e77825426
> Fixes: 03ef80b469d5 ("bcachefs: Ignore unknown mount options")
> Tested-by: [email protected]
> Signed-off-by: Gianfranco Trad <[email protected]>
looks correct, applied
> ---
> fs/bcachefs/errcode.h | 1 +
> fs/bcachefs/super-io.c | 5 +++++
> 2 files changed, 6 insertions(+)
>
> diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
> index 649263516ab1..b6cbd716000b 100644
> --- a/fs/bcachefs/errcode.h
> +++ b/fs/bcachefs/errcode.h
> @@ -222,6 +222,7 @@
> x(BCH_ERR_invalid_sb_layout, invalid_sb_layout_type)
> \
> x(BCH_ERR_invalid_sb_layout, invalid_sb_layout_nr_superblocks)
> \
> x(BCH_ERR_invalid_sb_layout, invalid_sb_layout_superblocks_overlap)
> \
> + x(BCH_ERR_invalid_sb_layout, invalid_sb_layout_sb_max_size_bits)
> \
> x(BCH_ERR_invalid_sb, invalid_sb_members_missing)
> \
> x(BCH_ERR_invalid_sb, invalid_sb_members)
> \
> x(BCH_ERR_invalid_sb, invalid_sb_disk_groups)
> \
> diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
> index ce7410d72089..44d0ac9b00dd 100644
> --- a/fs/bcachefs/super-io.c
> +++ b/fs/bcachefs/super-io.c
> @@ -287,6 +287,11 @@ static int validate_sb_layout(struct bch_sb_layout
> *layout, struct printbuf *out
> return -BCH_ERR_invalid_sb_layout_nr_superblocks;
> }
>
> + if (layout->sb_max_size_bits > BCH_SB_LAYOUT_SIZE_BITS_MAX) {
> + prt_printf(out, "Invalid superblock layout: max_size_bits too
> high");
> + return -BCH_ERR_invalid_sb_layout_sb_max_size_bits;
> + }
> +
> max_sectors = 1 << layout->sb_max_size_bits;
>
> prev_offset = le64_to_cpu(layout->sb_offset[0]);
> --
> 2.43.0
>
