From: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
Subject: zram: fix possible use after free in zcomp_create()
zcomp_create() verifies the success of zcomp_strm_{multi,single}_create()
through comp->stream, which can potentially be pointing to memory that was
freed if these functions returned an error.
While at it, replace a 'ERR_PTR(-ENOMEM)' by a more generic
'ERR_PTR(error)' as in the future zcomp_strm_{multi,siggle}_create() could
return other error codes. Function documentation updated accordingly.
Fixes: beca3ec71fe5 ("zram: add multi stream functionality")
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zcomp.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff -puN drivers/block/zram/zcomp.c~zram-fix-possible-use-after-free-in-zcomp_create drivers/block/zram/zcomp.c
--- a/drivers/block/zram/zcomp.c~zram-fix-possible-use-after-free-in-zcomp_create
+++ a/drivers/block/zram/zcomp.c
@@ -330,12 +330,14 @@ void zcomp_destroy(struct zcomp *comp)
* allocate new zcomp and initialize it. return compressing
* backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
* if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
- * case of allocation error.
+ * case of allocation error, or any other error potentially
+ * returned by functions zcomp_strm_{multi,single}_create.
*/
struct zcomp *zcomp_create(const char *compress, int max_strm)
{
struct zcomp *comp;
struct zcomp_backend *backend;
+ int error;
backend = find_backend(compress);
if (!backend)
@@ -347,12 +349,12 @@ struct zcomp *zcomp_create(const char *c
comp->backend = backend;
if (max_strm > 1)
- zcomp_strm_multi_create(comp, max_strm);
+ error = zcomp_strm_multi_create(comp, max_strm);
else
- zcomp_strm_single_create(comp);
- if (!comp->stream) {
+ error = zcomp_strm_single_create(comp);
+ if (error) {
kfree(comp);
- return ERR_PTR(-ENOMEM);
+ return ERR_PTR(error);
}
return comp;
}
_
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