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Commit 0040e606 authored by Christoph Jaeger's avatar Christoph Jaeger Committed by Chris Mason
Browse files

btrfs: fix use-after-free in mount_subvol() 



Pointer 'newargs' is used after the memory that it points to has already
been freed.

Picked up by Coverity - CID 1201425.

Fixes: 0723a047 ("btrfs: allow mounting btrfs subvolumes with
different ro/rw options")
Signed-off-by: default avatarChristoph Jaeger <christophjaeger@linux.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent e4fbaee2

fs/btrfs/super.c

+6 −2
Original line number Diff line number Diff line
@@ -1186,7 +1186,6 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags, 
		return ERR_PTR(-ENOMEM);

	mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,

			     newargs);

	kfree(newargs);



	if (PTR_RET(mnt) == -EBUSY) {

		if (flags & MS_RDONLY) {
@@ -1196,17 +1195,22 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags, 
			int r;

			mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY, device_name,

					     newargs);

			if (IS_ERR(mnt))

			if (IS_ERR(mnt)) {

				kfree(newargs);

				return ERR_CAST(mnt);

			}



			r = btrfs_remount(mnt->mnt_sb, &flags, NULL);

			if (r < 0) {

				/* FIXME: release vfsmount mnt ??*/

				kfree(newargs);

				return ERR_PTR(r);

			}

		}

	}



	kfree(newargs);



	if (IS_ERR(mnt))

		return ERR_CAST(mnt);