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zram: fix possible use after free in zcomp_create()

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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: beca3ec71f ("zram: add multi stream functionality")
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Luis Henriques 2015-09-17 16:01:40 -07:00 committed by Linus Torvalds
parent 72714841b7
commit 3aaf14da80
1 changed files with 7 additions and 5 deletions
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12
drivers/block/zram/zcomp.c
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@ -330,12 +330,14 @@ void zcomp_destroy(struct zcomp *comp)
* allocate new zcomp and initialize it. return compressing * allocate new zcomp and initialize it. return compressing
* backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL) * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
* if requested algorithm is not supported, ERR_PTR(-ENOMEM) in * 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 *zcomp_create(const char *compress, int max_strm)
{ {
struct zcomp *comp; struct zcomp *comp;
struct zcomp_backend *backend; struct zcomp_backend *backend;
int error;
backend = find_backend(compress); backend = find_backend(compress);
if (!backend) if (!backend)
@ -347,12 +349,12 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
comp->backend = backend; comp->backend = backend;
if (max_strm > 1) if (max_strm > 1)
zcomp_strm_multi_create(comp, max_strm); error = zcomp_strm_multi_create(comp, max_strm);
else else
zcomp_strm_single_create(comp); error = zcomp_strm_single_create(comp);
if (!comp->stream) { if (error) {
kfree(comp); kfree(comp);
return ERR_PTR(-ENOMEM); return ERR_PTR(error);
} }
return comp; return comp;
} }