Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757699Ab1DNQza (ORCPT ); Thu, 14 Apr 2011 12:55:30 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:52976 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757305Ab1DNQzZ (ORCPT ); Thu, 14 Apr 2011 12:55:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer; b=doxppPQAaqPR4oQL6YZeXlFBlnIohfsXSxFRTOmBB8fbxCBYmyB5PK5tJ6WPc4370A sDkidkHve0yXLP9276O7fWjWfz1V7d7Ct68imILzgHAqdLPO8F6/g7w/OJs0bdj4ev7H S/rBUrPWCh+xux+Jr1Aonb3lhe2WDQHFOmDBE= From: Vasiliy Kulikov To: linux-kernel@vger.kernel.org Cc: security@kernel.org, David Airlie Subject: [PATCH] char: agp: fix OOM and buffer overflow Date: Thu, 14 Apr 2011 20:55:19 +0400 Message-Id: <1302800120-31560-1-git-send-email-segoon@openwall.com> X-Mailer: git-send-email 1.7.0.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2255 Lines: 57 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 --- drivers/char/agp/generic.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c index 745e7ba..342df51 100644 --- a/drivers/char/agp/generic.c +++ b/drivers/char/agp/generic.c @@ -115,6 +115,9 @@ static struct agp_memory *agp_create_user_memory(unsigned long num_agp_pages) 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(struct agp_bridge_data *bridge, 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) { -- 1.7.0.4 -- 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/