This is a note to let you know that I've just added the patch titled
arm64: Mitigate MTE issues with str{n}cmp()
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-mitigate-mte-issues-with-str-n-cmp.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 59a68d4138086c015ab8241c3267eec5550fbd44 Mon Sep 17 00:00:00 2001
From: Robin Murphy <robin.murphy@xxxxxxx>
Date: Fri, 17 Sep 2021 15:59:30 +0100
Subject: arm64: Mitigate MTE issues with str{n}cmp()
From: Robin Murphy <robin.murphy@xxxxxxx>
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: <stable@xxxxxxxxxxxxxxx> # 5.14.x
Reported-by: Branislav Rankov <branislav.rankov@xxxxxxx>
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Link: https://lore.kernel.org/r/34dc4d12eec0adae49b0ac927df642ed10089d40.1631890770.git.robin.murphy@xxxxxxx
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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)
Patches currently in stable-queue which might be from robin.murphy@xxxxxxx are
queue-5.14/arm64-mitigate-mte-issues-with-str-n-cmp.patch
