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Thu, 12 Dec 2019 04:03:36 -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; Thu, 12 Dec 2019 04:00:00 -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, 12 Dec 2019 19:58:51 +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, 12 Dec 2019 19:58:45 +0800 From: Walter Wu To: Matthias Brugger , Thomas Gleixner , Alexander Potapenko , Josh Poimboeuf Subject: [PATCH v2] lib/stackdepot: Fix global out-of-bounds in stackdepot Date: Thu, 12 Dec 2019 19:58:48 +0800 Message-ID: <20191212115848.21687-1-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-20191212_040340_270414_271B9A52 X-CRM114-Status: GOOD ( 10.30 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-mediatek@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 Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.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 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 Signed-off-by: Walter Wu --- changes in v2: modify call flow sequence and preconditon --- 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; }