I would suggest to change rule r to the following. You had ... before and
after the big disjunction with the ||s, but that will limit the detection
of the problem to functions that contain only one occurrence.
(
v = f(...)@vs;
... when != v = e;
* (\( v@p <=@e 0 \| v@p >@e 0 \))
... when any
|
(
(\( v@p < 0 \| v@p <= 0 \)) || ... || (\( v >= c \| v > c \))
|
(\( v >= c \| v > c \)) || ... || (\( v@p < 0 \| v@p <= 0 \))
|
(\( v@p >= 0 \| v@p > 0 \)) && ... && (\( v < c \| v <= c \))
|
((\( v < c \| v <= c \) && ... && \( v@p >= 0 \| v@p > 0 \)))
|
* (\( v@p <@e 0 \| v@p >=@e 0 \))
)
)
julia
On Wed, 30 Dec 2015, Andrzej Hajda wrote:
> 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.ha...@samsung.com>
> ---
> 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 | 77
> ++++++++++++++++++++++
> 1 file changed, 77 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..b843392
> --- /dev/null
> +++ b/scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci
> @@ -0,0 +1,77 @@
> +/// 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_]+)$";
> +@@
> +
> +(
> + ...
> +(
> + (\( v@p < 0 \| v@p <= 0 \)) || ... || (\( v >= c \| v > c \))
> +|
> + (\( v >= c \| v > c \)) || ... || (\( v@p < 0 \| v@p <= 0 \))
> +|
> + (\( v@p >= 0 \| v@p > 0 \)) && ... && (\( v < c \| v <= c \))
> +|
> + ((\( v < c \| v <= c \) && ... && \( v@p >= 0 \| v@p > 0 \)))
> +|
> +* (\( v@p <@e 0 \| v@p >=@e 0 \))
> +)
> + ...
> +|
> + v = f(...)@vs;
> + ... when != v = e;
> +* (\( v@p <=@e 0 \| v@p >@e 0 \))
> + ...
> +)
> +
> +@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)
> +if e:
> + coccilib.report.print_report(p[0], msg)
> --
> 1.9.1
>
>
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