Nicolas Iooss <nicolas.iooss@xxxxxxx> writes: > When building libselinux on Fedora 33 with gcc 10.3.1, the compiler > reports: > > label_file.c: In function ‘lookup_all.isra’: > label_file.c:940:4: error: ‘strncpy’ specified bound depends on the > length of the source argument [-Werror=stringop-overflow=] > 940 | strncpy(clean_key, key, len - 1); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > label_file.c:927:8: note: length computed here > 927 | len = strlen(key); > | ^~~~~~~~~~~ > cc1: all warnings being treated as errors > > As clean_key is the result of malloc(len), there is no issue here. But > using strncpy can be considered as strange, because the size of the > string is already known and the NUL terminator is always added later, in > function ‘lookup_all.isra. > > Replace strncpy with memcpy to silence this gcc false-positive warning. > > Signed-off-by: Nicolas Iooss <nicolas.iooss@xxxxxxx> I wasn't able to reproduce it with gcc-11.0.1-0.7.fc35.x86_64, but it's indeed reproducible with gcc-10.3.1-1.fc33.x86_64 and this patch fixes it. Acked-by: Petr Lautrbach <plautrba@xxxxxxxxxx> > --- > libselinux/src/label_file.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c > index 726394ca4332..cfce23e0119e 100644 > --- a/libselinux/src/label_file.c > +++ b/libselinux/src/label_file.c > @@ -909,7 +909,7 @@ static const struct spec **lookup_all(struct selabel_handle *rec, > if (!clean_key) > goto finish; > > - strncpy(clean_key, key, len - 1); > + memcpy(clean_key, key, len - 1); > } > > clean_key[len - 1] = '\0'; > -- > 2.31.0
