From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Luis Henriques , Sergey Senozhatsky , Minchan Kim , Andrew Morton , Linus Torvalds Subject: [PATCH 4.1 28/29] zram: fix possible use after free in zcomp_create() Date: Thu, 1 Oct 2015 11:32:04 +0200 Message-Id: <20151001093146.944215251@linuxfoundation.org> In-Reply-To: <20151001093145.730759857@linuxfoundation.org> References: <20151001093145.730759857@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luis Henriques commit 3aaf14da807a4e9931a37f21e4251abb8a67021b upstream. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/block/zram/zcomp.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -325,12 +325,14 @@ 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) @@ -342,12 +344,12 @@ 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; }