On Wed, Aug 23, 2023 at 09:24:22PM +0000, Justin Stitt wrote: > `strncpy` is deprecated [1] and we should favor different interfaces. > > A suitable replacement is `strtomem_pad` as it is a more robust and less > ambiguous interface. In this case, the destination buffer is not > necessarily NUL-terminated as Heiko points out [2]. Using `strtomem_pad` > over strncpy means it is now more obvious what is expected of the > destination buffer: 1) Not necessarily NUL-terminated and 2) padded with > NUL-bytes > > Link: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings[1] > Link: https://lore.kernel.org/all/20230823134936.14378-E-hca@xxxxxxxxxxxxx/ [2] > Link: https://github.com/KSPP/linux/issues/90 > Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: linux-hardening@xxxxxxxxxxxxxxx > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> > --- > Changes in v2: > - prefer `strtomem_pad` over `strscpy` (thanks Kees) > - Link to v1: https://lore.kernel.org/r/20230822-strncpy-block-partitions-cmdline-ibm-v1-1-154dea8f755c@xxxxxxxxxx > --- > block/partitions/ibm.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c > index 403756dbd50d..56c076c5523d 100644 > --- a/block/partitions/ibm.c > +++ b/block/partitions/ibm.c > @@ -111,11 +111,11 @@ static int find_label(struct parsed_partitions *state, > !strcmp(temp, "LNX1") || > !strcmp(temp, "CMS1")) { > if (!strcmp(temp, "VOL1")) { > - strncpy(type, label->vol.vollbl, 4); > - strncpy(name, label->vol.volid, 6); > + strtomem_pad(type, label->vol.vollbl, 4); > + strtomem_pad(name, label->vol.volid, 6); > } else { > - strncpy(type, label->lnx.vollbl, 4); > - strncpy(name, label->lnx.volid, 6); > + strtomem_pad(type, label->lnx.vollbl, 4); > + strtomem_pad(name, label->lnx.volid, 6); > } > EBCASC(type, 4); > EBCASC(name, 6); This won't compile if find_label() is not inlined due the BUILD_BUG_ON() within strtomem_pad(). However instead of sending new versions, I think it would be better to ask Stefan and Jan to have a look at this. I think there is room for improvement with the string handling besides getting rid of strncpy(). And they know best the semantics of the (non-)strings.
