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Subject[PATCH v2] zram: fix possible use after free in zcomp_create()
Date
zcomp_create() verifies the success of zcomp_strm_{multi,siggle}_create()
through comp->stream, which can potentially be pointing to memory that was
freed if these functions returned an error.

Fixes: beca3ec71fe5 ("zram: add multi stream functionality")
Cc: stable@vger.kernel.org
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
Changes since v1:
* Check zcomp_strm_{multi,siggle}_create() return code instead
comp->stream (suggested by Sergey)

drivers/block/zram/zcomp.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 965d1afb0eaa..8d2cdfd307db 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -336,6 +336,7 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
{
struct zcomp *comp;
struct zcomp_backend *backend;
+ int ret;

backend = find_backend(compress);
if (!backend)
@@ -347,10 +348,10 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)

comp->backend = backend;
if (max_strm > 1)
- zcomp_strm_multi_create(comp, max_strm);
+ ret = zcomp_strm_multi_create(comp, max_strm);
else
- zcomp_strm_single_create(comp);
- if (!comp->stream) {
+ ret = zcomp_strm_single_create(comp);
+ if (ret) {
kfree(comp);
return ERR_PTR(-ENOMEM);
}

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