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Wed, 29 Jan 2020 22:54:35 -0800 Received: from MTKMBS06N1.mediatek.inc (172.21.101.129) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 29 Jan 2020 22:44:57 -0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs06n1.mediatek.inc (172.21.101.129) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 30 Jan 2020 14:44:31 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Thu, 30 Jan 2020 14:43:35 +0800 From: Walter Wu To: Dmitry Vyukov , Matthias Brugger , Thomas Gleixner , "Alexander Potapenko" , Josh Poimboeuf , "Greg Kroah-Hartman" , Kate Stewart Subject: [PATCH v3] lib/stackdepot: Fix global out-of-bounds in stackdepot Date: Thu, 30 Jan 2020 14:44:30 +0800 Message-ID: <20200130064430.17198-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200129_225442_241252_B0D10B67 X-CRM114-Status: GOOD ( 10.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Walter Wu , linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, wsd_upstream Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org If the depot_index = STACK_ALLOC_MAX_SLABS - 2 and next_slab_inited = 0, then it will cause array out-of-bounds access, so that we should modify the detection to avoid this array out-of-bounds bug. Assume depot_index = STACK_ALLOC_MAX_SLABS - 3 Consider following call flow sequence: stack_depot_save() depot_alloc_stack() if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) //pass depot_index++ //depot_index = STACK_ALLOC_MAX_SLABS - 2 if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) //enter smp_store_release(&next_slab_inited, 0); //next_slab_inited = 0 init_stack_slab() if (stack_slabs[depot_index] == NULL) //enter and exit stack_depot_save() depot_alloc_stack() if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) //pass depot_index++ //depot_index = STACK_ALLOC_MAX_SLABS - 1 init_stack_slab(&prealloc) stack_slabs[depot_index + 1] //here get global out-of-bounds Cc: Dmitry Vyukov Cc: Matthias Brugger Cc: Thomas Gleixner Cc: Alexander Potapenko Cc: Josh Poimboeuf Cc: Kate Stewart Cc: Greg Kroah-Hartman Cc: Kate Stewart Signed-off-by: Walter Wu --- changes in v2: modify call flow sequence and preconditon changes in v3: add some reviewers --- lib/stackdepot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index ed717dd08ff3..7e8a15e41600 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -106,7 +106,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN); if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) { - if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) { + if (unlikely(depot_index + 2 >= STACK_ALLOC_MAX_SLABS)) { WARN_ONCE(1, "Stack depot reached limit capacity"); return NULL; } -- 2.18.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel