From: Kursad Oney <kursad.oney@broadcom.com> stable inclusion from stable-v6.6.2 commit 7c8ad76067f85c84b1e980356f56d0aaaf2df86f category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8IW7G Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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: 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> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- arch/arm/lib/memset.S | 1 + 1 file changed, 1 insertion(+) 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 -- 2.25.1