Obviously, this isn't a bug. This warning message is printed using a
two step process. The first step makes a list of functions where one
parameter is the buffer and one parameter is the size. The second step
prints a warning if we call one of those functions with a buffer which
is smaller than the size.
This test is useful for copy_to_user() or something like that where
reading beyond the end of the array is a security problem.
Often when people call strncmp() with a string literal, it means that
they haven't thought very hard about how strcmp() and strncmp() work.
In this case though the string literal is a define so using strncmp()
makes sense, I suppose.
It's unlikely that using strncmp() with a larger than possible limit
will cause a bug so I will add strncmp() to the list of ignored
functions smatch_data/kernel.sizeof_param.remove
regards,
dan carpenter
---------------------
Hi Zhang,
FYI, there are new smatch warnings show up in
tree: git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux.git next
head: e79ca84d62d289b90cb39c80df83acf9f315a25c
commit: 635a1f41a8f95a35d1bf24c9cc018ffb018a93e6 [2/11] Thermal: thermal zone
governor fix
drivers/thermal/thermal_core.c:90 thermal_register_governor() error: strncmp()
'"step_wise"' too small (10 vs 20)
git remote add thermal
git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux.git
git remote update thermal
git checkout 635a1f41a8f95a35d1bf24c9cc018ffb018a93e6
vim +90 drivers/thermal/thermal_core.c
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 74
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 75 int
thermal_register_governor(struct thermal_governor *governor)
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 76 {
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 77 int err;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 78 const
char *name;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 79 struct
thermal_zone_device *pos;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 80
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 81 if
(!governor)
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 82
return -EINVAL;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 83
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 84
mutex_lock(&thermal_governor_lock);
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 85
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 86 err =
-EBUSY;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 87 if
(__find_governor(governor->name) == NULL) {
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 88
err = 0;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 89
list_add(&governor->governor_list, &thermal_governor_list);
635a1f41a drivers/thermal/thermal_core.c Zhang Rui 2014-01-24 @90
if (!def_governor && !strncmp(governor->name,
635a1f41a drivers/thermal/thermal_core.c Zhang Rui 2014-01-24 91
DEFAULT_THERMAL_GOVERNOR, THERMAL_NAME_LENGTH))
635a1f41a drivers/thermal/thermal_core.c Zhang Rui 2014-01-24 92
def_governor = governor;
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 93 }
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 94
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 95
mutex_lock(&thermal_list_lock);
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 96
a4a15485f drivers/thermal/thermal_sys.c Durgadoss R 2012-09-18 97
list_for_each_entry(pos, &thermal_tz_list, node) {
635a1f41a drivers/thermal/thermal_core.c Zhang Rui 2014-01-24 98
/*
---
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