Re: [PATCH v2] gfs2: reject oversized dinode sizes before i_size_write

Jiaming Zhang <[email protected]> 于2026年7月7日周二 02:00写道：
>
> A corrupted GFS2 image can store a dinode size that is larger than what VFS
> i_size can represent. gfs2_dinode_in() reads the on-disk di_size as a u64 and
> writes it directly into inode->i_size. If the value is larger than S64_MAX, the
> incore i_size becomes negative. That negative value can bypass the existing
> stuffed inode size check:
>
> inode->i_size > gfs2_max_stuffed_size(ip)
>
> Later, gfs2_quotad may try to sync the quota file and unstuff the quota inode.
> gfs2_unstuffer_folio() reads the negative i_size into an unsigned length and
> passes it to memcpy(), turning it into a huge copy size and triggering a
> out-of-bound issue.
>
> Reject dinodes whose size exceeds sb->s_maxbytes before storing the value in
> inode->i_size. Also make the stuffed inode check use the raw on-disk size while
> it is still unsigned.
>
> Fixes: 70376c7ff312 ("gfs2: Always check inode size of inline inodes")
> Closes: https://lore.kernel.org/lkml/CANypQFaF6bvORKKbRALvEL0k_epFaneFiOQqco4gjdmKVbdURg@mail.gmail.com/
> Assisted-by: Codex:gpt-5.5-xhigh
> Cc: [email protected]
> Signed-off-by: Jiaming Zhang <[email protected]>
> ---
> Changes in v2:
> - Drop the defensive unstuffing changes in bmap.c.
>
>  fs/gfs2/glops.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
> index 28f32424ee64..8c5d257451d5 100644
> --- a/fs/gfs2/glops.c
> +++ b/fs/gfs2/glops.c
> @@ -393,11 +393,16 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
>         umode_t mode = be32_to_cpu(str->di_mode);
>         struct inode *inode = &ip->i_inode;
>         bool is_new = inode_state_read_once(inode) & I_NEW;
> +       u64 size = be64_to_cpu(str->di_size);
>
>         if (unlikely(ip->i_no_addr != be64_to_cpu(str->di_num.no_addr))) {
>                 gfs2_consist_inode(ip);
>                 return -EIO;
>         }
> +       if (unlikely(size > (u64)inode->i_sb->s_maxbytes)) {
> +               gfs2_consist_inode(ip);
> +               return -EIO;
> +       }
>         if (unlikely(!is_new && inode_wrong_type(inode, mode))) {
>                 gfs2_consist_inode(ip);
>                 return -EIO;
> @@ -418,7 +423,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
>         i_uid_write(inode, be32_to_cpu(str->di_uid));
>         i_gid_write(inode, be32_to_cpu(str->di_gid));
>         set_nlink(inode, be32_to_cpu(str->di_nlink));
> -       i_size_write(inode, be64_to_cpu(str->di_size));
> +       i_size_write(inode, size);
>         gfs2_set_inode_blocks(inode, be64_to_cpu(str->di_blocks));
>         atime.tv_sec = be64_to_cpu(str->di_atime);
>         atime.tv_nsec = be32_to_cpu(str->di_atime_nsec);
> @@ -462,7 +467,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
>                 return -EIO;
>         }
>
> -       if (gfs2_is_stuffed(ip) && inode->i_size > gfs2_max_stuffed_size(ip)) {
> +       if (gfs2_is_stuffed(ip) && size > gfs2_max_stuffed_size(ip)) {
>                 gfs2_consist_inode(ip);
>                 return -EIO;
>         }
> --
> 2.43.0
>

Friendly ping. Please let me know if there's anything you'd like me to change.

Best Regards,
Jiaming Zhang