| Message ID | 20230613004402.3540432-1-azeemshaikh38@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | usbip: usbip_host: Replace strlcpy with strscpy | expand |
On Tue, Jun 13, 2023 at 12:44:02AM +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 -E2BIG > 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> > --- > drivers/usb/usbip/stub_main.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c > index e8c3131a8543..a92a284f5abb 100644 > --- a/drivers/usb/usbip/stub_main.c > +++ b/drivers/usb/usbip/stub_main.c > @@ -174,8 +174,8 @@ static ssize_t match_busid_store(struct device_driver *dev, const char *buf, > return -EINVAL; > > /* busid needs to include \0 termination */ > - len = strlcpy(busid, buf + 4, BUSID_SIZE); > - if (sizeof(busid) <= len) > + len = strscpy(busid, buf + 4, BUSID_SIZE); > + if (len == -E2BIG) > return -EINVAL; "len" is never used again, so maybe: if (strscpy(...) < 0) return -EINVAL; -Kees > > if (!strncmp(buf, "add ", 4)) { > -- > 2.41.0.162.gfafddb0af9-goog > >
On Tue, Jun 13, 2023 at 3:31 PM Kees Cook <keescook@chromium.org> wrote: > > On Tue, Jun 13, 2023 at 12:44:02AM +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 -E2BIG > > 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> > > --- > > drivers/usb/usbip/stub_main.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c > > index e8c3131a8543..a92a284f5abb 100644 > > --- a/drivers/usb/usbip/stub_main.c > > +++ b/drivers/usb/usbip/stub_main.c > > @@ -174,8 +174,8 @@ static ssize_t match_busid_store(struct device_driver *dev, const char *buf, > > return -EINVAL; > > > > /* busid needs to include \0 termination */ > > - len = strlcpy(busid, buf + 4, BUSID_SIZE); > > - if (sizeof(busid) <= len) > > + len = strscpy(busid, buf + 4, BUSID_SIZE); > > + if (len == -E2BIG) > > return -EINVAL; > > "len" is never used again, so maybe: > > if (strscpy(...) < 0) > return -EINVAL; > > -Kees > Thanks. Sent v2. > > > > if (!strncmp(buf, "add ", 4)) { > > -- > > 2.41.0.162.gfafddb0af9-goog > > > > > > -- > Kees Cook
diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c index e8c3131a8543..a92a284f5abb 100644 --- a/drivers/usb/usbip/stub_main.c +++ b/drivers/usb/usbip/stub_main.c @@ -174,8 +174,8 @@ static ssize_t match_busid_store(struct device_driver *dev, const char *buf, return -EINVAL; /* busid needs to include \0 termination */ - len = strlcpy(busid, buf + 4, BUSID_SIZE); - if (sizeof(busid) <= len) + len = strscpy(busid, buf + 4, BUSID_SIZE); + if (len == -E2BIG) 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 -E2BIG 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> --- drivers/usb/usbip/stub_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)