[cocci] [PATCH] squashfs: Improve exception handling in squashfs_decompressor_create()

[Markus Elfring <Markus.Elfring@web.de>]

Date: Thu, 30 Mar 2023 18:03:47 +0200

The label “out” was used to jump to a kfree() call despite of
the detail in the implementation of the function
“squashfs_decompressor_create” that it was determined already
that a corresponding variable contained a null pointer because of
a failed memory allocation.

Thus perform the following adjustments:

1. Return directly after a call of the function “kzalloc” failed
   at the beginning.

2. Use more appropriate labels instead.

3. Omit extra initialisations (for the variables “decomp_strm” and “err”)
   which became unnecessary with this refactoring.


This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 fs/squashfs/decompressor_multi.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/fs/squashfs/decompressor_multi.c b/fs/squashfs/decompressor_multi.c
index 416c53eedbd1..0a054ba4c541 100644
--- a/fs/squashfs/decompressor_multi.c
+++ b/fs/squashfs/decompressor_multi.c
@@ -62,12 +62,12 @@ static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
 				void *comp_opts)
 {
 	struct squashfs_stream *stream;
-	struct decomp_stream *decomp_strm = NULL;
-	int err = -ENOMEM;
+	struct decomp_stream *decomp_strm;
+	int err;

 	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
 	if (!stream)
-		goto out;
+		return ERR_PTR(-ENOMEM);

 	stream->comp_opts = comp_opts;
 	mutex_init(&stream->mutex);
@@ -81,22 +81,25 @@ static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
 	 * file system works.
 	 */
 	decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
-	if (!decomp_strm)
-		goto out;
+	if (!decomp_strm) {
+		err = -ENOMEM;
+		goto free_stream;
+	}

 	decomp_strm->stream = msblk->decompressor->init(msblk,
 						stream->comp_opts);
 	if (IS_ERR(decomp_strm->stream)) {
 		err = PTR_ERR(decomp_strm->stream);
-		goto out;
+		goto free_decomp_stream;
 	}

 	list_add(&decomp_strm->list, &stream->strm_list);
 	stream->avail_decomp = 1;
 	return stream;

-out:
+free_decomp_stream:
 	kfree(decomp_strm);
+free_stream:
 	kfree(stream);
 	return ERR_PTR(err);
 }
--
2.40.0