From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752818AbcAGJh0 (ORCPT ); Thu, 7 Jan 2016 04:37:26 -0500 Received: from mailout2.w1.samsung.com ([210.118.77.12]:10505 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751679AbcAGJhV (ORCPT ); Thu, 7 Jan 2016 04:37:21 -0500 X-AuditID: cbfec7f5-f79b16d000005389-50-568e31cf5d64 From: Andrzej Hajda To: Julia Lawall Cc: Andrzej Hajda , Bartlomiej Zolnierkiewicz , Marek Szyprowski , Gilles Muller , Nicolas Palix , Michal Marek , linux-kernel@vger.kernel.org (open list), cocci@systeme.lip6.fr (moderated list:COCCINELLE/Semantic Patches (SmPL)) Subject: [PATCH v7] coccinelle: tests: unsigned value cannot be lesser than zero Date: Thu, 07 Jan 2016 10:36:51 +0100 Message-id: <1452159411-3216-1-git-send-email-a.hajda@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: References: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrELMWRmVeSWpSXmKPExsVy+t/xK7rnDfvCDFZ18FvcWneO1WLjjPWs Fj82rWazmP3zEpPFsgenGS0u75rDZrH2yF12izmts9gsjr1czuTA6XHsWCuzx94tWR59W1Yx eqzfcpXF49Gy+ywenzfJBbBFcdmkpOZklqUW6dslcGWcWf2PrWC/dMWj1uVsDYyzxboYOTkk BEwkrjz7zAxhi0lcuLeerYuRi0NIYCmjxNHOJlYIp4lJovtPNxNIFZuApsTfzTfZQGwRAXWJ 1g27GEGKmAW+M0nMWnCDHSQhLBAg0XTrGthYFgFViQeHX4A18wo4SZx6dJoNYp2cxMljk4E2 cHBwClhKbPnrCBIWErCQuP95DssERt4FjAyrGEVTS5MLipPSc430ihNzi0vz0vWS83M3MUJC 7usOxqXHrA4xCnAwKvHwPsjoDRNiTSwrrsw9xCjBwawkwvvuPlCINyWxsiq1KD++qDQntfgQ ozQHi5I478xd70OEBNITS1KzU1MLUotgskwcnFINjOW9HI9tX6vOr2tNyhL+tNfny1X2D0vO /f2SEH/aacn26ROnTV+evH3Jo+zUtzqlU71CLwcEnN+9bnp+j4Zgtb6K1KMely094d5zGzaX p560lOU3PFn0jmnHBf2+EwUblFJ8pVyeKcfd4go208l9OqXx3CaJnsJXlWk7J/BK3thVXyxX YxbJocRSnJFoqMVcVJwIAMyeH4A1AgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Unsigned expressions cannot be lesser than zero. Presence of comparisons 'unsigned (<|<=|>|>=) 0' often indicates a bug, usually wrong type of variable. The patch beside finding such comparisons tries to eliminate false positives, mainly by bypassing range checks. gcc can detect such comparisons also using -Wtype-limits switch, but it warns also in correct cases, making too much noise. Signed-off-by: Andrzej Hajda --- v6: improved range check detection (according to Julia suggestion) v5: improved range check detection v4: added range check detection, added full check in case value holds a result of signed function v3: added bool type v2: added --all-includes option --- .../tests/unsigned_lesser_than_zero.cocci | 75 ++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci diff --git a/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci b/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci new file mode 100644 index 0000000..8fa5a3c --- /dev/null +++ b/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci @@ -0,0 +1,75 @@ +/// Unsigned expressions cannot be lesser than zero. Presence of +/// comparisons 'unsigned (<|<=|>|>=) 0' often indicates a bug, +/// usually wrong type of variable. +/// +/// To reduce number of false positives following tests have been added: +/// - parts of range checks are skipped, eg. "if (u < 0 || u > 15) ...", +/// developers prefer to keep such code, +/// - comparisons "<= 0" and "> 0" are performed only on results of +/// signed functions/macros, +/// - hardcoded list of signed functions/macros with always non-negative +/// result is used to avoid false positives difficult to detect by other ways +/// +// Confidence: Average +// Copyright: (C) 2015 Andrzej Hajda, Samsung Electronics Co., Ltd. GPLv2. +// URL: http://coccinelle.lip6.fr/ +// Options: --all-includes + +virtual context +virtual org +virtual report + +@r_cmp@ +position p; +typedef bool, u8, u16, u32, u64; +{unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, + size_t, bool, u8, u16, u32, u64} v; +expression e; +@@ + + \( v = e \| &v \) + ... + (\( v@p < 0 \| v@p <= 0 \| v@p >= 0 \| v@p > 0 \)) + +@r@ +position r_cmp.p; +typedef s8, s16, s32, s64; +{char, short, int, long, long long, ssize_t, s8, s16, s32, s64} vs; +expression c, e, v; +identifier f !~ "^(ata_id_queue_depth|btrfs_copy_from_user|dma_map_sg|dma_map_sg_attrs|fls|fls64|gameport_time|get_write_extents|nla_len|ntoh24|of_flat_dt_match|of_get_child_count|uart_circ_chars_pending|[A-Z0-9_]+)$"; +@@ + +( + v = f(...)@vs; + ... when != v = e; +* (\( v@p <=@e 0 \| v@p >@e 0 \)) + ... when any +| +( + (\( v@p < 0 \| v@p <= 0 \)) || ... || (\( v >= c \| v > c \)) +| + (\( v >= c \| v > c \)) || ... || (\( v@p < 0 \| v@p <= 0 \)) +| + (\( v@p >= 0 \| v@p > 0 \)) && ... && (\( v < c \| v <= c \)) +| + ((\( v < c \| v <= c \) && ... && \( v@p >= 0 \| v@p > 0 \))) +| +* (\( v@p <@e 0 \| v@p >=@e 0 \)) +) +) + +@script:python depends on org@ +p << r_cmp.p; +e << r.e; +@@ + +msg = "WARNING: Unsigned expression compared with zero: %s" % (e) +coccilib.org.print_todo(p[0], msg) + +@script:python depends on report@ +p << r_cmp.p; +e << r.e; +@@ + +msg = "WARNING: Unsigned expression compared with zero: %s" % (e) +coccilib.report.print_report(p[0], msg) -- 1.9.1