On Mon, Oct 23, 2023 at 07:50:57PM +0000, Justin Stitt wrote: > strncpy() is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > This pattern of strncpy(dest, src, strlen(src)) is extremely bug-prone. > This pattern basically never results in NUL-terminated destination > strings unless `dest` was zero-initialized. The current implementation > may be accidentally correct as tw_dev is zero-allocated via: > > host = scsi_host_alloc(&driver_template, sizeof(TW_Device_Extension)); > ... > tw_dev = shost_priv(host); > > ... wherein scsi_host_alloc zero-allocates host: > > shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL); > > Also, further suggesting this change is worthwhile is another strscpy() > usage in 32-9xxx.c: > > strscpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION, > sizeof(tw_dev->tw_compat_info.driver_version)); > > Considering the above, a suitable replacement is `strscpy` [2] due to > the fact that it guarantees NUL-termination on the destination buffer > without unnecessarily NUL-padding. > > Let's not be accidentally correct, let's be definitely correct. > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@xxxxxxxxxxxxxxx > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> Looks legit. Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
