On Thu, Aug 31, 2023 at 2:42 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > On Thu, Aug 31, 2023 at 02:36:38PM +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@xxxxxxxxx> > > --- > > v3: > > * Address readability comment. > > > > v2: > > * Replace all instances of strlcpy in this file instead of just 1. > > * https://lore.kernel.org/all/20230830210724.4156575-1-azeemshaikh38@xxxxxxxxx/ > > > > v1: > > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@xxxxxxxxx/ > > > > drivers/target/target_core_configfs.c | 24 ++++++++++++------------ > > 1 file changed, 12 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c > > index 936e5ff1b209..d5860c1c1f46 100644 > > --- a/drivers/target/target_core_configfs.c > > +++ b/drivers/target/target_core_configfs.c > > @@ -1392,16 +1392,16 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item, > > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > > unsigned char buf[INQUIRY_VENDOR_LEN + 2]; > > char *stripped = NULL; > > - size_t len; > > + ssize_t len; > > ssize_t ret; > > > > - len = strlcpy(buf, page, sizeof(buf)); > > - if (len < sizeof(buf)) { > > + len = strscpy(buf, page, sizeof(buf)); > > + if (len > 0) { > > /* Strip any newline added from userspace. */ > > stripped = strstrip(buf); > > len = strlen(stripped); > > } > > - if (len > INQUIRY_VENDOR_LEN) { > > + if (len < 0 || len > INQUIRY_VENDOR_LEN) { > > Agh, sorry I missed this before: the first "if" needs to be "len >= 0" > otherwise this: > > ret = target_check_inquiry_data(stripped); > > will be passing a NULL pointer... > Hmm, the current implementation of strscpy never returns 0. If sizeof(buf) is 0, it'll return -E2BIG. Do you still prefer that I update this to check for len >= 0?
