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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2016-05-20 16:59:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 17:58:30 -0700
commit1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef (patch)
tree5d3110f86fb5068fcffeebae794b49ddb2cd00d6 /lib/strncpy_from_user.c
parent64f8ebaf115bcddc4aaa902f981c57ba6506bc42 (diff)
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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.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 33840324138c..33f655ef48cd 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();