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Date: Sat, 25 Feb 2023 22:41:46 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Tony Lindgren <tony@...mide.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Frederic Weisbecker <frederic@...nel.org>,
Sasha Levin <sashal@...nel.org>, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
x86@...nel.org, ryabinin.a.a@...il.com, jpoimboe@...nel.org,
keescook@...omium.org, samitolvanen@...gle.com,
kasan-dev@...glegroups.com, linux-mm@...ck.org
Subject: [PATCH AUTOSEL 6.2 17/21] entry, kasan, x86: Disallow overriding mem*() functions
From: Peter Zijlstra <peterz@...radead.org>
[ Upstream commit 69d4c0d3218692ffa56b0e1b9c76c50c699d7044 ]
KASAN cannot just hijack the mem*() functions, it needs to emit
__asan_mem*() variants if it wants instrumentation (other sanitizers
already do this).
vmlinux.o: warning: objtool: sync_regs+0x24: call to memcpy() leaves .noinstr.text section
vmlinux.o: warning: objtool: vc_switch_off_ist+0xbe: call to memcpy() leaves .noinstr.text section
vmlinux.o: warning: objtool: fixup_bad_iret+0x36: call to memset() leaves .noinstr.text section
vmlinux.o: warning: objtool: __sev_get_ghcb+0xa0: call to memcpy() leaves .noinstr.text section
vmlinux.o: warning: objtool: __sev_put_ghcb+0x35: call to memcpy() leaves .noinstr.text section
Remove the weak aliases to ensure nobody hijacks these functions and
add them to the noinstr section.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Tested-by: Tony Lindgren <tony@...mide.com>
Tested-by: Ulf Hansson <ulf.hansson@...aro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Frederic Weisbecker <frederic@...nel.org>
Link: https://lore.kernel.org/r/20230112195542.028523143@infradead.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
arch/x86/lib/memcpy_64.S | 5 ++---
arch/x86/lib/memmove_64.S | 4 +++-
arch/x86/lib/memset_64.S | 4 +++-
mm/kasan/kasan.h | 4 ++++
mm/kasan/shadow.c | 38 ++++++++++++++++++++++++++++++++++++++
tools/objtool/check.c | 3 +++
6 files changed, 53 insertions(+), 5 deletions(-)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index dd8cd8831251f..a64017602010e 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -8,7 +8,7 @@
#include <asm/alternative.h>
#include <asm/export.h>
-.pushsection .noinstr.text, "ax"
+.section .noinstr.text, "ax"
/*
* We build a jump to memcpy_orig by default which gets NOPped out on
@@ -43,7 +43,7 @@ SYM_TYPED_FUNC_START(__memcpy)
SYM_FUNC_END(__memcpy)
EXPORT_SYMBOL(__memcpy)
-SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy)
+SYM_FUNC_ALIAS(memcpy, __memcpy)
EXPORT_SYMBOL(memcpy)
/*
@@ -184,4 +184,3 @@ SYM_FUNC_START_LOCAL(memcpy_orig)
RET
SYM_FUNC_END(memcpy_orig)
-.popsection
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 724bbf83eb5b0..02661861e5dd9 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -13,6 +13,8 @@
#undef memmove
+.section .noinstr.text, "ax"
+
/*
* Implement memmove(). This can handle overlap between src and dst.
*
@@ -213,5 +215,5 @@ SYM_FUNC_START(__memmove)
SYM_FUNC_END(__memmove)
EXPORT_SYMBOL(__memmove)
-SYM_FUNC_ALIAS_WEAK(memmove, __memmove)
+SYM_FUNC_ALIAS(memmove, __memmove)
EXPORT_SYMBOL(memmove)
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index fc9ffd3ff3b21..6143b1a6fa2ca 100644
--- a/arch/x86/lib/memset_64.S
+++ b/arch/x86/lib/memset_64.S
@@ -6,6 +6,8 @@
#include <asm/alternative.h>
#include <asm/export.h>
+.section .noinstr.text, "ax"
+
/*
* ISO C memset - set a memory block to a byte value. This function uses fast
* string to get better performance than the original function. The code is
@@ -43,7 +45,7 @@ SYM_FUNC_START(__memset)
SYM_FUNC_END(__memset)
EXPORT_SYMBOL(__memset)
-SYM_FUNC_ALIAS_WEAK(memset, __memset)
+SYM_FUNC_ALIAS(memset, __memset)
EXPORT_SYMBOL(memset)
/*
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index ea8cf1310b1e8..71c15438afcfc 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -618,6 +618,10 @@ void __asan_set_shadow_f3(const void *addr, size_t size);
void __asan_set_shadow_f5(const void *addr, size_t size);
void __asan_set_shadow_f8(const void *addr, size_t size);
+void *__asan_memset(void *addr, int c, size_t len);
+void *__asan_memmove(void *dest, const void *src, size_t len);
+void *__asan_memcpy(void *dest, const void *src, size_t len);
+
void __hwasan_load1_noabort(unsigned long addr);
void __hwasan_store1_noabort(unsigned long addr);
void __hwasan_load2_noabort(unsigned long addr);
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 15cfb34d16a13..3703983a8e556 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -38,6 +38,12 @@ bool __kasan_check_write(const volatile void *p, unsigned int size)
}
EXPORT_SYMBOL(__kasan_check_write);
+#ifndef CONFIG_GENERIC_ENTRY
+/*
+ * CONFIG_GENERIC_ENTRY relies on compiler emitted mem*() calls to not be
+ * instrumented. KASAN enabled toolchains should emit __asan_mem*() functions
+ * for the sites they want to instrument.
+ */
#undef memset
void *memset(void *addr, int c, size_t len)
{
@@ -68,6 +74,38 @@ void *memcpy(void *dest, const void *src, size_t len)
return __memcpy(dest, src, len);
}
+#endif
+
+void *__asan_memset(void *addr, int c, size_t len)
+{
+ if (!kasan_check_range((unsigned long)addr, len, true, _RET_IP_))
+ return NULL;
+
+ return __memset(addr, c, len);
+}
+EXPORT_SYMBOL(__asan_memset);
+
+#ifdef __HAVE_ARCH_MEMMOVE
+void *__asan_memmove(void *dest, const void *src, size_t len)
+{
+ if (!kasan_check_range((unsigned long)src, len, false, _RET_IP_) ||
+ !kasan_check_range((unsigned long)dest, len, true, _RET_IP_))
+ return NULL;
+
+ return __memmove(dest, src, len);
+}
+EXPORT_SYMBOL(__asan_memmove);
+#endif
+
+void *__asan_memcpy(void *dest, const void *src, size_t len)
+{
+ if (!kasan_check_range((unsigned long)src, len, false, _RET_IP_) ||
+ !kasan_check_range((unsigned long)dest, len, true, _RET_IP_))
+ return NULL;
+
+ return __memcpy(dest, src, len);
+}
+EXPORT_SYMBOL(__asan_memcpy);
void kasan_poison(const void *addr, size_t size, u8 value, bool init)
{
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4b7c8b33069e5..3bd5bbfb4dee0 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1082,6 +1082,9 @@ static const char *uaccess_safe_builtin[] = {
"__asan_store16_noabort",
"__kasan_check_read",
"__kasan_check_write",
+ "__asan_memset",
+ "__asan_memmove",
+ "__asan_memcpy",
/* KASAN in-line */
"__asan_report_load_n_noabort",
"__asan_report_load1_noabort",
--
2.39.0
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