Commit 59a68d41 authored by Robin Murphy's avatar Robin Murphy Committed by Catalin Marinas
Browse files

arm64: Mitigate MTE issues with str{n}cmp() 



As with strlen(), the patches importing the updated str{n}cmp()
implementations were originally developed and tested before the
advent of CONFIG_KASAN_HW_TAGS, and have subsequently revealed
not to be MTE-safe. Since in-kernel MTE is still a rather niche
case, let it temporarily fall back to the generic C versions for
correctness until we can figure out the best fix.

Fixes: 758602c0 ("arm64: Import latest version of Cortex Strings' strcmp")
Fixes: 020b199b ("arm64: Import latest version of Cortex Strings' strncmp")
Cc: <stable@vger.kernel.org> # 5.14.x
Reported-by: default avatarBranislav Rankov <branislav.rankov@arm.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/34dc4d12eec0adae49b0ac927df642ed10089d40.1631890770.git.robin.murphy@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 8c8a3b5b

arch/arm64/include/asm/assembler.h

+5 −0
Original line number Diff line number Diff line
@@ -525,6 +525,11 @@ alternative_endif 
#define EXPORT_SYMBOL_NOKASAN(name)	EXPORT_SYMBOL(name)

#endif



#ifdef CONFIG_KASAN_HW_TAGS

#define EXPORT_SYMBOL_NOHWKASAN(name)

#else

#define EXPORT_SYMBOL_NOHWKASAN(name)	EXPORT_SYMBOL_NOKASAN(name)

#endif

	/*

	 * Emit a 64-bit absolute little endian symbol reference in a way that

	 * ensures that it will be resolved at build time, even when building a

arch/arm64/include/asm/string.h

+2 −0
Original line number Diff line number Diff line
@@ -12,11 +12,13 @@ extern char *strrchr(const char *, int c); 
#define __HAVE_ARCH_STRCHR

extern char *strchr(const char *, int c);



#ifndef CONFIG_KASAN_HW_TAGS

#define __HAVE_ARCH_STRCMP

extern int strcmp(const char *, const char *);



#define __HAVE_ARCH_STRNCMP

extern int strncmp(const char *, const char *, __kernel_size_t);

#endif



#define __HAVE_ARCH_STRLEN

extern __kernel_size_t strlen(const char *);

arch/arm64/lib/strcmp.S

+1 −1
Original line number Diff line number Diff line
@@ -173,4 +173,4 @@ L(done): 
	ret



SYM_FUNC_END_PI(strcmp)

EXPORT_SYMBOL_NOKASAN(strcmp)
 
EXPORT_SYMBOL_NOHWKASAN(strcmp)

arch/arm64/lib/strncmp.S

+1 −1
Original line number Diff line number Diff line
@@ -258,4 +258,4 @@ L(ret0): 
	ret



SYM_FUNC_END_PI(strncmp)

EXPORT_SYMBOL_NOKASAN(strncmp)
 
EXPORT_SYMBOL_NOHWKASAN(strncmp)