[PATCH] fs/squashfs: handle possible null pointer

[Peng Hao]

 in squashfs_fill_super:

        msblk->decompressor = supported_squashfs_filesystem(
                        fc,
                        le16_to_cpu(sblk->s_major),
                        le16_to_cpu(sblk->s_minor),
                        le16_to_cpu(sblk->compression));
        if (msblk->decompressor == NULL)
                goto failed_mount;
        ...

failed_mount:
	...
	squashfs_decompressor_destroy(msblk);

in squashfs_decompressor_destroy:
	if (stream) {
        	msblk->decompressor->free(stream->stream);
msblk->decompressor is NULL.

so add a judgment whether a null pointer.

Signed-off-by: Peng Hao <flyingpeng@xxxxxxxxxxx>
---
 fs/squashfs/decompressor_single.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/squashfs/decompressor_single.c b/fs/squashfs/decompressor_single.c
index 4eb3d083d45e..a155452bbc54 100644
--- a/fs/squashfs/decompressor_single.c
+++ b/fs/squashfs/decompressor_single.c
@@ -54,7 +54,8 @@ void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
 	struct squashfs_stream *stream = msblk->stream;
 
 	if (stream) {
-		msblk->decompressor->free(stream->stream);
+		if (msblk->decompressor)
+			msblk->decompressor->free(stream->stream);
 		kfree(stream);
 	}
 }
-- 
2.27.0