From: Mark Rutland mark.rutland@arm.com
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@arm.com Acked-by: Kees Cook keescook@chromium.org Signed-off-by: Mark Rutland mark.rutland@arm.com Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Alex Shi alex.shi@linaro.org --- 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;