From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753828AbeE3Lme (ORCPT ); Wed, 30 May 2018 07:42:34 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60677 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751874AbeE3LG6 (ORCPT ); Wed, 30 May 2018 07:06:58 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Boris Brezillon" , "Linus Walleij" Date: Wed, 30 May 2018 11:52:42 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 153/153] mtd: jedec_probe: Fix crash in jedec_read_mfr() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.102-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Linus Walleij commit 87a73eb5b56fd6e07c8e499fe8608ef2d8912b82 upstream. It turns out that the loop where we read manufacturer jedec_read_mfd() can under some circumstances get a CFI_MFR_CONTINUATION repeatedly, making the loop go over all banks and eventually hit the end of the map and crash because of an access violation: Unable to handle kernel paging request at virtual address c4980000 pgd = (ptrval) [c4980000] *pgd=03808811, *pte=00000000, *ppte=00000000 Internal error: Oops: 7 [#1] PREEMPT ARM CPU: 0 PID: 1 Comm: swapper Not tainted 4.16.0-rc1+ #150 Hardware name: Gemini (Device Tree) PC is at jedec_probe_chip+0x6ec/0xcd0 LR is at 0x4 pc : [] lr : [<00000004>] psr: 60000013 sp : c382dd18 ip : 0000ffff fp : 00000000 r10: c0626388 r9 : 00020000 r8 : c0626340 r7 : 00000000 r6 : 00000001 r5 : c3a71afc r4 : c382dd70 r3 : 00000001 r2 : c4900000 r1 : 00000002 r0 : 00080000 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 0000397f Table: 00004000 DAC: 00000053 Process swapper (pid: 1, stack limit = 0x(ptrval)) Fix this by breaking the loop with a return 0 if the offset exceeds the map size. Fixes: 5c9c11e1c47c ("[MTD] [NOR] Add support for flash chips with ID in bank other than 0") Signed-off-by: Linus Walleij Signed-off-by: Boris Brezillon Signed-off-by: Ben Hutchings --- drivers/mtd/chips/jedec_probe.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/mtd/chips/jedec_probe.c +++ b/drivers/mtd/chips/jedec_probe.c @@ -1888,6 +1888,8 @@ static inline u32 jedec_read_mfr(struct do { uint32_t ofs = cfi_build_cmd_addr(0 + (bank << 8), map, cfi); mask = (1 << (cfi->device_type * 8)) - 1; + if (ofs >= map->size) + return 0; result = map_read(map, base + ofs); bank++; } while ((result.x[0] & mask) == CFI_MFR_CONTINUATION);