[PATCH 1/2] lib: test_scanf: Fix incorrect use of type_min() with unsigned types
From: Richard Fitzgerald <rf@opensource.cirrus.com>
Date: 2021-05-24 16:09:23
Also in:
lkml
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
sparse was producing warnings of the form:
sparse: cast truncates bits from constant value (ffff0001 becomes 1)
The problem was that value_representable_in_type() compared unsigned types
against type_min(). But type_min() is only valid for signed types because
it is calculating the value -type_max() - 1. The minimum value of an
unsigned is obviously 0, so only type_max() need be tested.
This patch also takes the opportunity to clean up the implementation of
simple_numbers_loop() to use a common pattern for the positive and
negative test.
Reported-by: kernel test robot <redacted>
Fixes: 17aadada455d ("lib: test_scanf: Add tests for sscanf number conversion")
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
lib/test_scanf.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/lib/test_scanf.c b/lib/test_scanf.c
index 8d577aec6c28..48ff5747a4da 100644
--- a/lib/test_scanf.c
+++ b/lib/test_scanf.c@@ -187,8 +187,8 @@ static const unsigned long long numbers[] __initconst = { #define value_representable_in_type(T, val) \ (is_signed_type(T) \ ? ((long long)(val) >= type_min(T)) && ((long long)(val) <= type_max(T)) \ - : ((unsigned long long)(val) >= type_min(T)) && \ - ((unsigned long long)(val) <= type_max(T))) + : ((unsigned long long)(val) <= type_max(T))) + #define test_one_number(T, gen_fmt, scan_fmt, val, fn) \ do { \
@@ -204,12 +204,11 @@ do { \ int i; \ \ for (i = 0; i < ARRAY_SIZE(numbers); i++) { \ - if (!value_representable_in_type(T, numbers[i])) \ - continue; \ - \ - test_one_number(T, gen_fmt, scan_fmt, numbers[i], fn); \ + if (value_representable_in_type(T, numbers[i])) \ + test_one_number(T, gen_fmt, scan_fmt, \ + numbers[i], fn); \ \ - if (is_signed_type(T)) \ + if (value_representable_in_type(T, -numbers[i])) \ test_one_number(T, gen_fmt, scan_fmt, \ -numbers[i], fn); \ } \
--
2.20.1