[PATCH 5.14 045/162] arm64: Mitigate MTE issues with str{n}cmp()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-09-27 17:21:13
Also in:
lkml
From: Robin Murphy <robin.murphy@arm.com>
commit 59a68d4138086c015ab8241c3267eec5550fbd44 upstream.
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: 758602c04409 ("arm64: Import latest version of Cortex Strings' strcmp")
Fixes: 020b199bc70d ("arm64: Import latest version of Cortex Strings' strncmp")
Cc: <redacted> # 5.14.x
Reported-by: Branislav Rankov <redacted>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/34dc4d12eec0adae49b0ac927df642ed10089d40.1631890770.git.robin.murphy@arm.com (local)
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/assembler.h | 5 +++++
arch/arm64/include/asm/string.h | 2 ++
arch/arm64/lib/strcmp.S | 2 +-
arch/arm64/lib/strncmp.S | 2 +-
4 files changed, 9 insertions(+), 2 deletions(-)
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h@@ -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 --- a/arch/arm64/include/asm/string.h +++ b/arch/arm64/include/asm/string.h
@@ -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 *); --- a/arch/arm64/lib/strcmp.S +++ b/arch/arm64/lib/strcmp.S
@@ -173,4 +173,4 @@ L(done): ret SYM_FUNC_END_PI(strcmp) -EXPORT_SYMBOL_NOKASAN(strcmp) +EXPORT_SYMBOL_NOHWKASAN(strcmp) --- a/arch/arm64/lib/strncmp.S +++ b/arch/arm64/lib/strncmp.S
@@ -258,4 +258,4 @@ L(ret0): ret SYM_FUNC_END_PI(strncmp) -EXPORT_SYMBOL_NOKASAN(strncmp) +EXPORT_SYMBOL_NOHWKASAN(strncmp)