diff options
| author | Kursad Oney <kursad.oney@broadcom.com> | 2023-08-22 15:06:06 +0100 |
|---|---|---|
| committer | Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2023-10-05 16:15:41 +0100 |
| commit | c0e824661f443b8cab3897006c1bbc69fd0e7bc4 (patch) | |
| tree | 4777fe6507121b220985c4687b539ee54485db09 /arch/arm/lib | |
| parent | b0150014878c32197cfa66e3e2f79e57f66babc0 (diff) | |
ARM: 9321/1: memset: cast the constant byte to unsigned char
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: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kursad Oney <kursad.oney@broadcom.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/lib')
| -rw-r--r-- | arch/arm/lib/memset.S | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S index d71ab61430b2..de75ae4d5ab4 100644 --- a/arch/arm/lib/memset.S +++ b/arch/arm/lib/memset.S @@ -17,6 +17,7 @@ ENTRY(__memset) ENTRY(mmioset) WEAK(memset) UNWIND( .fnstart ) + and r1, r1, #255 @ cast to unsigned char ands r3, r0, #3 @ 1 unaligned? mov ip, r0 @ preserve r0 as return value bne 6f @ 1 |