From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933832AbaLBTra (ORCPT ); Tue, 2 Dec 2014 14:47:30 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:46688 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753102AbaLBTXb (ORCPT ); Tue, 2 Dec 2014 14:23:31 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Weijie Yang , Sergey Senozhatsky , Dan Streetman , Nitin Gupta , Weijie Yang , Andrew Morton , Linus Torvalds , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 084/121] zram: avoid kunmap_atomic() of a NULL pointer Date: Tue, 2 Dec 2014 11:19:23 -0800 Message-Id: <1417548000-1794-85-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1417548000-1794-1-git-send-email-kamal@canonical.com> References: <1417548000-1794-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Weijie Yang commit c406515239376fc93a30d5d03192182160cbd3fb upstream. zram could kunmap_atomic() a NULL pointer in a rare situation: a zram page becomes a full-zeroed page after a partial write io. The current code doesn't handle this case and performs kunmap_atomic() on a NULL pointer, which panics the kernel. This patch fixes this issue. Signed-off-by: Weijie Yang Cc: Sergey Senozhatsky Cc: Dan Streetman Cc: Nitin Gupta Cc: Weijie Yang Acked-by: Jerome Marchand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- drivers/staging/zram/zram_drv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index e2f0add..63c2a5b 100644 --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -430,7 +430,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, } if (page_zero_filled(uncmem)) { - kunmap_atomic(user_mem); + if (user_mem) + kunmap_atomic(user_mem); /* Free memory associated with this sector now. */ zram_free_page(zram, index); -- 1.9.1