diff mbox series

[v2] ext4: Detect already used quota file early

Message ID 20201015110330.28716-1-jack@suse.cz
State Awaiting Upstream
Headers show
Series [v2] ext4: Detect already used quota file early | expand

Commit Message

Jan Kara Oct. 15, 2020, 11:03 a.m. UTC
When we try to use file already used as a quota file again (for the same
or different quota type), strange things can happen. At the very least
lockdep annotations may be wrong but also inode flags may be wrongly set
/ reset. When the file is used for two quota types at once we can even
corrupt the file and likely crash the kernel. Catch all these cases by
checking whether passed file is already used as quota file and bail
early in that case.

This fixes occasional generic/219 failure due to lockdep complaint.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/super.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Theodore Y. Ts'o Oct. 15, 2020, 2:56 p.m. UTC | #1
On Thu, Oct 15, 2020 at 01:03:30PM +0200, Jan Kara wrote:
> When we try to use file already used as a quota file again (for the same
> or different quota type), strange things can happen. At the very least
> lockdep annotations may be wrong but also inode flags may be wrongly set
> / reset. When the file is used for two quota types at once we can even
> corrupt the file and likely crash the kernel. Catch all these cases by
> checking whether passed file is already used as quota file and bail
> early in that case.
> 
> This fixes occasional generic/219 failure due to lockdep complaint.
> 
> Reviewed-by: Andreas Dilger <adilger@dilger.ca>
> Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
> Signed-off-by: Jan Kara <jack@suse.cz>

Replied to the wrong patch previously.  Thanks, applied.

	       	     	   		- Ted
diff mbox series

Patch

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ea425b49b345..d31ae5a87859 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6042,6 +6042,11 @@  static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 	/* Quotafile not on the same filesystem? */
 	if (path->dentry->d_sb != sb)
 		return -EXDEV;
+
+	/* Quota already enabled for this file? */
+	if (IS_NOQUOTA(d_inode(path->dentry)))
+		return -EBUSY;
+
 	/* Journaling quota? */
 	if (EXT4_SB(sb)->s_qf_names[type]) {
 		/* Quotafile not in fs root? */