From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fk-out-0910.google.com ([209.85.128.188]) by canuck.infradead.org with esmtp (Exim 4.63 #1 (Red Hat Linux)) id 1IH6YL-0004A7-KT for linux-mtd@lists.infradead.org; Fri, 03 Aug 2007 19:27:33 -0400 Received: by fk-out-0910.google.com with SMTP id 19so1496875fkr for ; Fri, 03 Aug 2007 16:27:28 -0700 (PDT) From: Jesper Juhl To: Artem Bityutskiy Subject: [PATCH] UBI: Don't use signed int as array index before testing if it is negative Date: Sat, 4 Aug 2007 01:25:26 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200708040125.26861.jesper.juhl@gmail.com> Cc: David Woodhouse , Jesper Juhl , linux-mtd@lists.infradead.org, Linux Kernel Mailing List List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, I can't find anything guaranteeing that 'ubi_num' cannot be <0 in drivers/mtd/ubi/kapi.c::ubi_open_volume(), and in fact the code even tests for that and errors out if so. Unfortunately the test for "ubi_num < 0" happens after we've already used 'ubi_num' as an array index - bad thing to do if it is negative. This patch moves the test earlier in the function and then moves the indexing using that variable after the check. A bit safer :-) Signed-off-by: Jesper Juhl --- drivers/mtd/ubi/kapi.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c index 4a458e8..5130e54 100644 --- a/drivers/mtd/ubi/kapi.c +++ b/drivers/mtd/ubi/kapi.c @@ -99,16 +99,21 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode) { int err; struct ubi_volume_desc *desc; - struct ubi_device *ubi = ubi_devices[ubi_num]; + struct ubi_device *ubi; struct ubi_volume *vol; dbg_msg("open device %d volume %d, mode %d", ubi_num, vol_id, mode); err = -ENODEV; + if (ubi_num < 0) + return ERR_PTR(err); + + ubi = ubi_devices[ubi_num]; + if (!try_module_get(THIS_MODULE)) return ERR_PTR(err); - if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES || !ubi) + if (ubi_num >= UBI_MAX_DEVICES || !ubi) goto out_put; err = -EINVAL;