7b0e690456
[ Upstream commit c0e824661f443b8cab3897006c1bbc69fd0e7bc4 ]
memset() description in ISO/IEC 9899:1999 (and elsewhere) says:
The memset function copies the value of c (converted to an
unsigned char) into each of the first n characters of the
object pointed to by s.
The kernel's arm32 memset does not cast c to unsigned char. This results
in the following code to produce erroneous output:
char a[128];
memset(a, -128, sizeof(a));
This is because gcc will generally emit the following code before
it calls memset() :
mov r0, r7
mvn r1, #127 ; 0x7f
bl 00000000 <memset>
r1 ends up with 0xffffff80 before being used by memset() and the
'a' array will have -128 once in every four bytes while the other
bytes will be set incorrectly to -1 like this (printing the first
8 bytes) :
test_module: -128 -1 -1 -1
test_module: -1 -1 -1 -128
The change here is to 'and' r1 with 255 before it is used.
Fixes:
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.. | ||
alpha | ||
arc | ||
arm | ||
arm64 | ||
c6x | ||
h8300 | ||
hexagon | ||
ia64 | ||
m68k | ||
microblaze | ||
mips | ||
nds32 | ||
nios2 | ||
openrisc | ||
parisc | ||
powerpc | ||
riscv | ||
s390 | ||
sh | ||
sparc | ||
um | ||
unicore32 | ||
x86 | ||
xtensa | ||
.gitignore | ||
Kconfig |