Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933648Ab1D2TBL (ORCPT ); Fri, 29 Apr 2011 15:01:11 -0400 Received: from kroah.org ([198.145.64.141]:35122 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933632Ab1D2S6u (ORCPT ); Fri, 29 Apr 2011 14:58:50 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Apr 29 11:56:57 2011 Message-Id: <20110429185657.451172472@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Fri, 29 Apr 2011 11:56:13 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Vasiliy Kulikov , Dave Airlie Subject: [50/55] agp: fix OOM and buffer overflow In-Reply-To: <20110429185706.GA12824@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2380 Lines: 65 2.6.38-stable review patch. If anyone has any objections, please let us know. ------------------ From: Vasiliy Kulikov commit b522f02184b413955f3bc952e3776ce41edc6355 upstream. page_count is copied from userspace. agp_allocate_memory() tries to check whether this number is too big, but doesn't take into account the wrap case. Also agp_create_user_memory() doesn't check whether alloc_size is calculated from num_agp_pages variable without overflow. This may lead to allocation of too small buffer with following buffer overflow. Another problem in agp code is not addressed in the patch - kernel memory exhaustion (AGPIOC_RESERVE and AGPIOC_ALLOCATE ioctls). It is not checked whether requested pid is a pid of the caller (no check in agpioc_reserve_wrap()). Each allocation is limited to 16KB, though, there is no per-process limit. This might lead to OOM situation, which is not even solved in case of the caller death by OOM killer - the memory is allocated for another (faked) process. Signed-off-by: Vasiliy Kulikov Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/char/agp/generic.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/char/agp/generic.c +++ b/drivers/char/agp/generic.c @@ -115,6 +115,9 @@ static struct agp_memory *agp_create_use struct agp_memory *new; unsigned long alloc_size = num_agp_pages*sizeof(struct page *); + if (INT_MAX/sizeof(struct page *) < num_agp_pages) + return NULL; + new = kzalloc(sizeof(struct agp_memory), GFP_KERNEL); if (new == NULL) return NULL; @@ -234,11 +237,14 @@ struct agp_memory *agp_allocate_memory(s int scratch_pages; struct agp_memory *new; size_t i; + int cur_memory; if (!bridge) return NULL; - if ((atomic_read(&bridge->current_memory_agp) + page_count) > bridge->max_memory_agp) + cur_memory = atomic_read(&bridge->current_memory_agp); + if ((cur_memory + page_count > bridge->max_memory_agp) || + (cur_memory + page_count < page_count)) return NULL; if (type >= AGP_USER_TYPES) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/