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authorPeter Zijlstra <peterz@infradead.org>2023-01-12 20:43:58 +0100
committerIngo Molnar <mingo@kernel.org>2023-01-13 11:48:17 +0100
commit69d4c0d3218692ffa56b0e1b9c76c50c699d7044 (patch)
tree632f322958ef60af5237ba029b2b82e5b4595c5d /mm/kasan
parent365bd03ff63fb7433a49c453472cf54830b677bf (diff)
entry, kasan, x86: Disallow overriding mem*() functions
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@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20230112195542.028523143@infradead.org
Diffstat (limited to 'mm/kasan')
-rw-r--r--mm/kasan/kasan.h4
-rw-r--r--mm/kasan/shadow.c38
2 files changed, 42 insertions, 0 deletions
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index ea8cf1310b1e..71c15438afcf 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 2fba1f51f042..98269936a5e4 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)
{