1// SPDX-License-Identifier: GPL-2.0-only 2/// Unsigned expressions cannot be lesser than zero. Presence of 3/// comparisons 'unsigned (<|<=|>|>=) 0' often indicates a bug, 4/// usually wrong type of variable. 5/// 6/// To reduce number of false positives following tests have been added: 7/// - parts of range checks are skipped, eg. "if (u < 0 || u > 15) ...", 8/// developers prefer to keep such code, 9/// - comparisons "<= 0" and "> 0" are performed only on results of 10/// signed functions/macros, 11/// - hardcoded list of signed functions/macros with always non-negative 12/// result is used to avoid false positives difficult to detect by other ways 13/// 14// Confidence: Average 15// Copyright: (C) 2015 Andrzej Hajda, Samsung Electronics Co., Ltd. 16// URL: https://coccinelle.gitlabpages.inria.fr/website 17// Options: --all-includes 18 19virtual context 20virtual org 21virtual report 22 23@r_cmp@ 24position p; 25typedef bool, u8, u16, u32, u64; 26{unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, 27 size_t, bool, u8, u16, u32, u64} v; 28expression e; 29@@ 30 31 \( v = e \| &v \) 32 ... 33 (\( v@p < 0 \| v@p <= 0 \| v@p >= 0 \| v@p > 0 \)) 34 35@r@ 36position r_cmp.p; 37typedef s8, s16, s32, s64; 38{char, short, int, long, long long, ssize_t, s8, s16, s32, s64} vs; 39expression c, e, v; 40identifier 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_]+)$"; 41@@ 42 43( 44 v = f(...)@vs; 45 ... when != v = e; 46* (\( v@p <=@e 0 \| v@p >@e 0 \)) 47 ... when any 48| 49( 50 (\( v@p < 0 \| v@p <= 0 \)) || ... || (\( v >= c \| v > c \)) 51| 52 (\( v >= c \| v > c \)) || ... || (\( v@p < 0 \| v@p <= 0 \)) 53| 54 (\( v@p >= 0 \| v@p > 0 \)) && ... && (\( v < c \| v <= c \)) 55| 56 ((\( v < c \| v <= c \) && ... && \( v@p >= 0 \| v@p > 0 \))) 57| 58* (\( v@p <@e 0 \| v@p >=@e 0 \)) 59) 60) 61 62@script:python depends on org@ 63p << r_cmp.p; 64e << r.e; 65@@ 66 67msg = "WARNING: Unsigned expression compared with zero: %s" % (e) 68coccilib.org.print_todo(p[0], msg) 69 70@script:python depends on report@ 71p << r_cmp.p; 72e << r.e; 73@@ 74 75msg = "WARNING: Unsigned expression compared with zero: %s" % (e) 76coccilib.report.print_report(p[0], msg) 77