strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
Signed-off-by: Azeem Shaikh <[email protected]>
---
v3:
* Removed declaration of @len to fix build failures in v2.
v2:
* https://lore.kernel.org/all/[email protected]/
* Use "< 0" instead of "== -E2BIG".
v1:
* https://lore.kernel.org/all/[email protected]/
drivers/usb/usbip/stub_main.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c
index e8c3131a8543..0a6624d37929 100644
--- a/drivers/usb/usbip/stub_main.c
+++ b/drivers/usb/usbip/stub_main.c
@@ -167,15 +167,13 @@ static ssize_t match_busid_show(struct device_driver *drv, char *buf)
static ssize_t match_busid_store(struct device_driver *dev, const char *buf,
size_t count)
{
- int len;
char busid[BUSID_SIZE];
if (count < 5)
return -EINVAL;
/* busid needs to include \0 termination */
- len = strlcpy(busid, buf + 4, BUSID_SIZE);
- if (sizeof(busid) <= len)
+ if (strscpy(busid, buf + 4, BUSID_SIZE) < 0)
return -EINVAL;
if (!strncmp(buf, "add ", 4)) {
--
2.41.0.162.gfafddb0af9-goog
On Thu, Jun 15, 2023 at 06:05:04PM +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
>
> Direct replacement is safe here since return value of -errno
> is used to check for truncation instead of sizeof(dest).
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
>
> Signed-off-by: Azeem Shaikh <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On 6/21/23 21:10, Kees Cook wrote:
> On Thu, Jun 15, 2023 at 06:05:04PM +0000, Azeem Shaikh wrote:
>> strlcpy() reads the entire source buffer first.
>> This read may exceed the destination size limit.
>> This is both inefficient and can lead to linear read
>> overflows if a source string is not NUL-terminated [1].
>> In an effort to remove strlcpy() completely [2], replace
>> strlcpy() here with strscpy().
>>
>> Direct replacement is safe here since return value of -errno
>> is used to check for truncation instead of sizeof(dest).
>>
>> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
>> [2] https://github.com/KSPP/linux/issues/89
>>
>> Signed-off-by: Azeem Shaikh <[email protected]>
>
> Reviewed-by: Kees Cook <[email protected]>
>
Acked-by: Shuah Khan <[email protected]>
thanks,
-- Shuah