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| author | Andrzej Hajda <a.hajda@samsung.com> | 2016-01-07 10:36:51 +0100 |
|---|---|---|
| committer | Michal Marek <mmarek@suse.com> | 2016-01-12 17:47:47 +0100 |
| commit | 3f984cb39907f87515d83657ecd471ae396a6c4a (patch) | |
| tree | 28ae00d701f940cedc277d73295c80220bdb8239 | |
| parent | 93209d65c1d38f86ffb3f61a1214130b581a9709 (diff) | |
| download | linux-stable-3f984cb39907f87515d83657ecd471ae396a6c4a.tar.gz linux-stable-3f984cb39907f87515d83657ecd471ae396a6c4a.tar.bz2 linux-stable-3f984cb39907f87515d83657ecd471ae396a6c4a.zip | |
coccinelle: tests: unsigned value cannot be lesser than zero
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 <a.hajda@samsung.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.com>
| -rw-r--r-- | scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci | 75 |
1 files changed, 75 insertions, 0 deletions
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 000000000000..8fa5a3c7b784 --- /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) |