[PATCH 5.0 075/117] btrfs: prop: fix zstd compression parameter validation

Greg Kroah-Hartman
2019-04-15T19:12:29Z

From: Anand Jain <anand.jain@oracle.com>

commit 50398fde997f6be8faebdb5f38e9c9c467370f51 upstream.

We let pass zstd compression parameter even if it is not fully valid.
For example:

$ btrfs prop set /btrfs compression zst
$ btrfs prop get /btrfs compression
compression=zst

zlib and lzo are fine.

Fix it by checking the correct prefix length.

Fixes: 5c1aab1dd544 ("btrfs: Add zstd support")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/props.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -396,7 +396,7 @@ static int prop_compression_apply(struct
btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
} else if (!strncmp("zlib", value, 4)) {
type = BTRFS_COMPRESS_ZLIB;
- } else if (!strncmp("zstd", value, len)) {
+ } else if (!strncmp("zstd", value, 4)) {
type = BTRFS_COMPRESS_ZSTD;
btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
} else {