Re: [PATCH v2] ocfs2: don't BUG_ON an invalid journal dinode

[Joseph Qi <joseph.qi@linux.alibaba.com>]

On 5/12/26 10:41 AM, ZhengYuan Huang wrote:
> [BUG]
> A fuzzed OCFS2 image can corrupt the current slot journal dinode while
> mount is still in progress. The mount path first reports the invalid
> journal block and then crashes in shutdown:
> 
> kernel BUG at fs/ocfs2/journal.c:1034!
> Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
> RIP: 0010:ocfs2_journal_toggle_dirty+0x2d6/0x340 fs/ocfs2/journal.c:1034
> Call Trace:
>  ocfs2_journal_shutdown+0x414/0xc30 fs/ocfs2/journal.c:1116
>  ocfs2_mount_volume fs/ocfs2/super.c:1785 [inline]
>  ocfs2_fill_super+0x30a9/0x3cd0 fs/ocfs2/super.c:1083
>  get_tree_bdev_flags+0x38b/0x640 fs/super.c:1698
>  get_tree_bdev+0x24/0x40 fs/super.c:1721
>  ocfs2_get_tree+0x21/0x30 fs/ocfs2/super.c:1184
>  vfs_get_tree+0x9a/0x370 fs/super.c:1758
>  fc_mount fs/namespace.c:1199 [inline]
>  do_new_mount_fc fs/namespace.c:3642 [inline]
>  do_new_mount fs/namespace.c:3718 [inline]
>  path_mount+0x5b8/0x1ea0 fs/namespace.c:4028
>  do_mount fs/namespace.c:4041 [inline]
>  __do_sys_mount fs/namespace.c:4229 [inline]
>  __se_sys_mount fs/namespace.c:4206 [inline]
>  __x64_sys_mount+0x282/0x320 fs/namespace.c:4206
>  ...
> 
> [CAUSE]
> ocfs2_journal_toggle_dirty() used to return -EIO when journal->j_bh no
> longer contained a valid dinode, because the startup and shutdown paths
> already handled that failure. Commit 10995aa2451a
> ("ocfs2: Morph the haphazard OCFS2_IS_VALID_DINODE() checks.") changed
> the check to a BUG_ON() under the assumption that the journal dinode had
> already been validated. That turns an unexpected invalid journal dinode
> during mount teardown into a kernel crash instead of a normal mount
> failure.
> 
> [FIX]
> Replace the BUG_ON() with WARN_ON() and return -EIO. This keeps the
> invariant warning for debugging, but restores the original behavior of
> failing startup or shutdown cleanly instead of panicking the kernel.
> 
> Fixes: 10995aa2451a ("ocfs2: Morph the haphazard OCFS2_IS_VALID_DINODE() checks.")
> Signed-off-by: ZhengYuan Huang <gality369@gmail.com>

The 'Fixes' tag may not needed. Other looks fine to me.
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
> ---
> v2:
> - Drop the full dinode revalidation and use WARN_ON plus -EIO instead
> - Rework the rationale around the historical BUG_ON conversion
> - Add a Fixes tag for the commit that replaced the old error return
> ---
>  fs/ocfs2/journal.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index f9bf3bac085d..fc54cc798ce3 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -1022,11 +1022,8 @@ static int ocfs2_journal_toggle_dirty(struct ocfs2_super *osb,
>  	struct ocfs2_dinode *fe;
>  
>  	fe = (struct ocfs2_dinode *)bh->b_data;
> -
> -	/* The journal bh on the osb always comes from ocfs2_journal_init()
> -	 * and was validated there inside ocfs2_inode_lock_full().  It's a
> -	 * code bug if we mess it up. */
> -	BUG_ON(!OCFS2_IS_VALID_DINODE(fe));
> +	if (WARN_ON(!OCFS2_IS_VALID_DINODE(fe)))
> +		return -EIO;
>  
>  	flags = le32_to_cpu(fe->id1.journal1.ij_flags);
>  	if (dirty)