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SubjectRe: [PATCH] zram: fix possible use after free in zcomp_create()
On (09/07/15 11:33), Luis Henriques wrote:
> 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.
>

good catch.

we probably better start checking the zcomp_strm_multi_create()/
zcomp_strm_single_create() status in zcomp_create(); that's much
more obvious and that's why we return it in the first place.

what do you think?

---

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 3456d5a..16bbc8c 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -360,6 +360,7 @@ 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)
@@ -371,10 +372,10 @@ 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 != 0) {
kfree(comp);
return ERR_PTR(-ENOMEM);
}


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