| Message ID | 20230615180504.401169-1-azeemshaikh38@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] usbip: usbip_host: Replace strlcpy with strscpy | expand |
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 <azeemshaikh38@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org>
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 <azeemshaikh38@gmail.com> > > Reviewed-by: Kees Cook <keescook@chromium.org> > Acked-by: Shuah Khan <skhan@linuxfoundation.org> thanks, -- Shuah
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)) {
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 <azeemshaikh38@gmail.com> --- v3: * Removed declaration of @len to fix build failures in v2. v2: * https://lore.kernel.org/all/20230614141026.2113749-1-azeemshaikh38@gmail.com/ * Use "< 0" instead of "== -E2BIG". v1: * https://lore.kernel.org/all/20230613004402.3540432-1-azeemshaikh38@gmail.com/ drivers/usb/usbip/stub_main.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)