[PATCH 01/24] fix default __strnlen_user macro
From: Ryan Mallon <hidden>
Date: 2011-08-31 23:31:13
Also in:
lkml
On 01/09/11 07:26, Mark Salter wrote:
quoted hunk ↗ jump to hunk
The existing __strnlen_user macro simply resolved to strnlen. However, the count returned by strnlen_user should include the NULL byte. This patch fixes the __strnlen_user macro to include the NULL byte in the count. Signed-off-by: Mark Salter<redacted> --- include/asm-generic/uaccess.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h index ac68c99..1d0fdf8 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h@@ -289,7 +289,7 @@ strncpy_from_user(char *dst, const char __user *src, long count) * Return 0 on exception, a value greater than N if too long */ #ifndef __strnlen_user -#define __strnlen_user strnlen +#define __strnlen_user(s, n) (strnlen((s), (n)) + 1) #endif
I don't think this is correct because if you hit maxlen you will add one
to it. e.g. __strnlen_user("abcd\0", 3) would return 4 instead of 3.
It should probably be something like this:
#define __strnlen_user(s, n) ({ \
size_t k = strnlen(s, n); \
k< n ? k + 1 : n; })
I wonder if this change will break anything since it has been incorrect
(according to the comment in uaccess.h@least) for a while. Why does
__strnlen_user have different semantics to strnlen anway?
~Ryan