From: Mark Rutland <mark.rutland@xxxxxxx>
commit 76624175dca upstream.
Currently in arm64's copy_{to,from}_user, we only check the
source/destination object size if access_ok() tells us the user access
is permissible.
However, in copy_from_user() we'll subsequently zero any remainder on
the destination object. If we failed the access_ok() check, that applies
to the whole object size, which we didn't check.
To ensure that we catch that case, this patch hoists check_object_size()
to the start of copy_from_user(), matching __copy_from_user() and
__copy_to_user(). To make all of our uaccess copy primitives consistent,
the same is done to copy_to_user().
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxx>
---
arch/arm64/include/asm/uaccess.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 94e1457..09c9b59 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -326,9 +326,9 @@ static inline unsigned long __must_check copy_from_user(void *to, const void __u
{
unsigned long res = n;
kasan_check_write(to, n);
+ check_object_size(to, n, false);
if (access_ok(VERIFY_READ, from, n)) {
- check_object_size(to, n, false);
res = __arch_copy_from_user(to, from, n);
}
if (unlikely(res))
@@ -339,9 +339,9 @@ static inline unsigned long __must_check copy_from_user(void *to, const void __u
static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
{
kasan_check_read(from, n);
+ check_object_size(from, n, true);
if (access_ok(VERIFY_WRITE, to, n)) {
- check_object_size(from, n, true);
n = __arch_copy_to_user(to, from, n);
}
return n;
--
2.7.4