From: Andrey Konovalov <[email protected]>
After commit 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*()
functions") and the follow-up fixes, with CONFIG_FORTIFY_SOURCE enabled,
even though the compiler instruments meminstrinsics by generating calls
to __asan/__hwasan_ prefixed functions, FORTIFY_SOURCE still uses
uninstrumented memset/memmove/memcpy as the underlying functions.
As a result, KASAN cannot detect bad accesses in memset/memmove/memcpy.
This also makes KASAN tests corrupt kernel memory and cause crashes.
To fix this, use __asan_/__hwasan_memset/memmove/memcpy as the underlying
functions whenever appropriate. Do this only for the instrumented code
(as indicated by __SANITIZE_ADDRESS__).
Reported-by: Erhard Furtner <[email protected]>
Reported-by: Nico Pache <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Fixes: 51287dcb00cc ("kasan: emit different calls for instrumentable memintrinsics")
Fixes: 36be5cba99f6 ("kasan: treat meminstrinsic as builtins in uninstrumented files")
Signed-off-by: Andrey Konovalov <[email protected]>
---
include/linux/fortify-string.h | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 85fc0e6f0f7f..bac010cfc42f 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -75,17 +75,30 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
__ret; \
})
-#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+#if defined(__SANITIZE_ADDRESS__)
+
+#if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
+extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
+extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
+extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
+#elif defined(CONFIG_KASAN_GENERIC)
+extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset);
+extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove);
+extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy);
+#else /* CONFIG_KASAN_SW_TAGS */
+extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset);
+extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove);
+extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy);
+#endif
+
extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
-extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
-extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
-extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
+
#else
#if defined(__SANITIZE_MEMORY__)
@@ -110,6 +123,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
#define __underlying_strlen __builtin_strlen
#define __underlying_strncat __builtin_strncat
#define __underlying_strncpy __builtin_strncpy
+
#endif
/**
--
2.25.1
On Fri, 17 May 2024 at 15:01, <[email protected]> wrote:
>
> From: Andrey Konovalov <[email protected]>
>
> After commit 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*()
> functions") and the follow-up fixes, with CONFIG_FORTIFY_SOURCE enabled,
> even though the compiler instruments meminstrinsics by generating calls
> to __asan/__hwasan_ prefixed functions, FORTIFY_SOURCE still uses
> uninstrumented memset/memmove/memcpy as the underlying functions.
>
> As a result, KASAN cannot detect bad accesses in memset/memmove/memcpy.
> This also makes KASAN tests corrupt kernel memory and cause crashes.
>
> To fix this, use __asan_/__hwasan_memset/memmove/memcpy as the underlying
> functions whenever appropriate. Do this only for the instrumented code
> (as indicated by __SANITIZE_ADDRESS__).
>
> Reported-by: Erhard Furtner <[email protected]>
> Reported-by: Nico Pache <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
> Fixes: 51287dcb00cc ("kasan: emit different calls for instrumentable memintrinsics")
> Fixes: 36be5cba99f6 ("kasan: treat meminstrinsic as builtins in uninstrumented files")
> Signed-off-by: Andrey Konovalov <[email protected]>
Reviewed-by: Marco Elver <[email protected]>
This is getting rather complex, but I don't see a better way either.
> ---
> include/linux/fortify-string.h | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
> index 85fc0e6f0f7f..bac010cfc42f 100644
> --- a/include/linux/fortify-string.h
> +++ b/include/linux/fortify-string.h
> @@ -75,17 +75,30 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
> __ret; \
> })
>
> -#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> +#if defined(__SANITIZE_ADDRESS__)
> +
> +#if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
> +extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
> +extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
> +extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
> +#elif defined(CONFIG_KASAN_GENERIC)
> +extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset);
> +extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove);
> +extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy);
> +#else /* CONFIG_KASAN_SW_TAGS */
> +extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset);
> +extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove);
> +extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy);
> +#endif
> +
> extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
> extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
> -extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
> -extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
> -extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
> extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
> extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
> extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
> extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
> extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
> +
> #else
>
> #if defined(__SANITIZE_MEMORY__)
> @@ -110,6 +123,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
> #define __underlying_strlen __builtin_strlen
> #define __underlying_strncat __builtin_strncat
> #define __underlying_strncpy __builtin_strncpy
> +
> #endif
>
> /**
> --
> 2.25.1
>
On Fri, May 17, 2024 at 7:02 AM <[email protected]> wrote:
>
> From: Andrey Konovalov <[email protected]>
>
> After commit 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*()
> functions") and the follow-up fixes, with CONFIG_FORTIFY_SOURCE enabled,
> even though the compiler instruments meminstrinsics by generating calls
> to __asan/__hwasan_ prefixed functions, FORTIFY_SOURCE still uses
> uninstrumented memset/memmove/memcpy as the underlying functions.
>
> As a result, KASAN cannot detect bad accesses in memset/memmove/memcpy.
> This also makes KASAN tests corrupt kernel memory and cause crashes.
>
> To fix this, use __asan_/__hwasan_memset/memmove/memcpy as the underlying
> functions whenever appropriate. Do this only for the instrumented code
> (as indicated by __SANITIZE_ADDRESS__).
>
> Reported-by: Erhard Furtner <[email protected]>
> Reported-by: Nico Pache <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
> Fixes: 51287dcb00cc ("kasan: emit different calls for instrumentable memintrinsics")
> Fixes: 36be5cba99f6 ("kasan: treat meminstrinsic as builtins in uninstrumented files")
> Signed-off-by: Andrey Konovalov <[email protected]>
Thank you for fixing this !! The test no longer panics :)
Now that the test progresses I also see rcu_uaf failing.
# rcu_uaf: EXPECTATION FAILED at mm/kasan/kasan_test.c:870
KASAN failure expected in "call_rcu(&global_rcu_ptr->rcu,
rcu_uaf_reclaim); rcu_barrier()", but none occurred
not ok 31 rcu_uaf
I can open a new thread for that if you'd like.
Tested-by: Nico Pache <[email protected]>
Acked-by: Nico Pache <[email protected]>
> ---
> include/linux/fortify-string.h | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
> index 85fc0e6f0f7f..bac010cfc42f 100644
> --- a/include/linux/fortify-string.h
> +++ b/include/linux/fortify-string.h
> @@ -75,17 +75,30 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
> __ret; \
> })
>
> -#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> +#if defined(__SANITIZE_ADDRESS__)
> +
> +#if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
> +extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
> +extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
> +extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
> +#elif defined(CONFIG_KASAN_GENERIC)
> +extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset);
> +extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove);
> +extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy);
> +#else /* CONFIG_KASAN_SW_TAGS */
> +extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset);
> +extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove);
> +extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy);
> +#endif
> +
> extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
> extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
> -extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
> -extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
> -extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
> extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
> extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
> extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
> extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
> extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
> +
> #else
>
> #if defined(__SANITIZE_MEMORY__)
> @@ -110,6 +123,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
> #define __underlying_strlen __builtin_strlen
> #define __underlying_strncat __builtin_strncat
> #define __underlying_strncpy __builtin_strncpy
> +
> #endif
>
> /**
> --
> 2.25.1
>
On Fri, May 17, 2024 at 9:50 PM Nico Pache <[email protected]> wrote:
>
> Thank you for fixing this !! The test no longer panics :)
Awesome, thank you for testing!
> Now that the test progresses I also see rcu_uaf failing.
> # rcu_uaf: EXPECTATION FAILED at mm/kasan/kasan_test.c:870
> KASAN failure expected in "call_rcu(&global_rcu_ptr->rcu,
> rcu_uaf_reclaim); rcu_barrier()", but none occurred
> not ok 31 rcu_uaf
> I can open a new thread for that if you'd like.
Looks like something else is broken :(
Unfortunately, I failed to boot a kernel built with the config that
you provided in QEMU.
If you can provide a config that boots in QEMU or instructions on how
to reproduce the issue, I can take a look.
Thanks!