From 3aaf14da807a4e9931a37f21e4251abb8a67021b Mon Sep 17 00:00:00 2001 From: Luis Henriques Date: Thu, 17 Sep 2015 16:01:40 -0700 Subject: [PATCH] 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 Acked-by: Sergey Senozhatsky Acked-by: Minchan Kim Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zcomp.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index 965d1afb0eaa..5cb13ca3a3ac 100644 --- a/drivers/block/zram/zcomp.c +++ b/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 *compress, int max_strm) 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; }