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| author | Andrey Ryabinin <aryabinin@virtuozzo.com> | 2016-05-20 16:59:31 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-20 17:58:30 -0700 |
| commit | 1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef (patch) | |
| tree | 5d3110f86fb5068fcffeebae794b49ddb2cd00d6 /lib/strncpy_from_user.c | |
| parent | 64f8ebaf115bcddc4aaa902f981c57ba6506bc42 (diff) | |
| download | linux-0-day-1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef.tar.gz linux-0-day-1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef.tar.xz | |
x86/kasan: instrument user memory access API
Exchange between user and kernel memory is coded in assembly language.
Which means that such accesses won't be spotted by KASAN as a compiler
instruments only C code.
Add explicit KASAN checks to user memory access API to ensure that
userspace writes to (or reads from) a valid kernel memory.
Note: Unlike others strncpy_from_user() is written mostly in C and KASAN
sees memory accesses in it. However, it makes sense to add explicit
check for all @count bytes that *potentially* could be written to the
kernel.
[aryabinin@virtuozzo.com: move kasan check under the condition]
Link: http://lkml.kernel.org/r/1462869209-21096-1-git-send-email-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/1462538722-1574-4-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/strncpy_from_user.c')
| -rw-r--r-- | lib/strncpy_from_user.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index 33840324138c2..33f655ef48cd1 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -1,5 +1,6 @@ #include <linux/compiler.h> #include <linux/export.h> +#include <linux/kasan-checks.h> #include <linux/uaccess.h> #include <linux/kernel.h> #include <linux/errno.h> @@ -109,6 +110,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count) unsigned long max = max_addr - src_addr; long retval; + kasan_check_write(dst, count); user_access_begin(); retval = do_strncpy_from_user(dst, src, count, max); user_access_end(); |