From: "Tobin C. Harding" <tobin@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: "Tobin C. Harding" <tobin@kernel.org>,
Shuah Khan <shuah@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org
Subject: [PATCH 5/6] lib: Fix function documentation for strncpy_from_user
Date: Tue, 19 Feb 2019 10:23:07 +1100 [thread overview]
Message-ID: <20190218232308.11241-6-tobin@kernel.org> (raw)
In-Reply-To: <20190218232308.11241-1-tobin@kernel.org>
Current function documentation for strncpy_from_user() is incorrect. If
@count (size of destination buffer) is less than the length of the user
string the function does _not_ return @count but rather returns -EFAULT.
Document correctly the function return value, also add note that string
may be left non-null terminated.
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
---
lib/strncpy_from_user.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 58eacd41526c..11fe9a4a00fd 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -82,22 +82,19 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
}
/**
- * strncpy_from_user: - Copy a NUL terminated string from userspace.
+ * strncpy_from_user() - Copy a NUL terminated string from userspace.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
* @src: Source address, in user space.
- * @count: Maximum number of bytes to copy, including the trailing NUL.
+ * @count: Maximum number of bytes to copy, including the trailing %NUL.
*
* Copies a NUL-terminated string from userspace to kernel space.
*
- * On success, returns the length of the string (not including the trailing
- * NUL).
- *
- * If access to userspace fails, returns -EFAULT (some data may have been
- * copied).
- *
- * If @count is smaller than the length of the string, copies @count bytes
- * and returns @count.
+ * Return: If access to userspace fails, returns -EFAULT. Otherwise,
+ * return the number of characters copied excluding the trailing
+ * %NUL, if the length of the user string exceeds @count return
+ * -EFAULT (in which case @dst will be left without a %NUL
+ * terminator).
*/
long strncpy_from_user(char *dst, const char __user *src, long count)
{
--
2.20.1
next prev parent reply other threads:[~2019-02-18 23:23 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 23:23 [PATCH 0/6] lib: Add safe string funtions Tobin C. Harding
2019-02-18 23:23 ` [PATCH 1/6] lib/string: Enable string selftesting Tobin C. Harding
2019-02-19 10:55 ` Andy Shevchenko
2019-02-19 21:55 ` Tobin C. Harding
2019-02-20 10:49 ` Andy Shevchenko
2019-02-20 23:58 ` Kees Cook
2019-02-20 23:57 ` Kees Cook
2019-02-21 5:16 ` Tobin C. Harding
2019-02-18 23:23 ` [PATCH 2/6] lib/string: Fix erroneous 'overflow' documentation Tobin C. Harding
2019-02-21 0:02 ` Kees Cook
2019-02-21 5:17 ` Tobin C. Harding
2019-02-18 23:23 ` [PATCH 3/6] lib/string: Use correct docstring format Tobin C. Harding
2019-02-21 0:07 ` Kees Cook
2019-02-21 4:14 ` Randy Dunlap
2019-02-21 5:27 ` Kees Cook
2019-02-18 23:23 ` [PATCH 4/6] lib/string: Add string copy/zero function Tobin C. Harding
2019-02-21 0:48 ` Kees Cook
2019-02-21 5:20 ` Tobin C. Harding
2019-02-21 12:02 ` Andy Shevchenko
2019-02-25 20:09 ` Tobin C. Harding
2019-02-18 23:23 ` Tobin C. Harding [this message]
2019-02-19 0:51 ` [PATCH 5/6] lib: Fix function documentation for strncpy_from_user Jann Horn
2019-02-19 21:52 ` Tobin C. Harding
2019-02-21 1:05 ` Kees Cook
2019-02-21 5:24 ` Tobin C. Harding
2019-02-21 6:02 ` Kees Cook
2019-02-21 14:58 ` Rasmus Villemoes
2019-02-21 23:03 ` Kees Cook
2019-02-25 15:41 ` Rasmus Villemoes
2019-02-21 16:06 ` Jann Horn
2019-02-21 23:14 ` Kees Cook
2019-02-21 20:26 ` Stephen Rothwell
2019-02-21 23:16 ` Kees Cook
2019-02-21 14:28 ` Jann Horn
2019-02-21 22:52 ` Kees Cook
2019-02-18 23:23 ` [PATCH 6/6] lib: Add function strscpy_from_user() Tobin C. Harding
2019-02-19 2:09 ` Jann Horn
2019-02-19 2:12 ` Jann Horn
2019-02-19 21:53 ` Tobin C. Harding
2019-02-20 23:31 ` [PATCH 0/6] lib: Add safe string funtions Kees Cook
2019-02-21 5:15 ` Tobin C. Harding
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