From: Mike Frysinger <[email protected]> Date: Thu, 5 Mar 2015 00:47:08 -0500
> The NLMSG_OK macro compares three things: > - the len arg from the user > - a size_t: sizeof(struct nlmsghdr) > - an int: sizeof(struct nlmsghdr) casted > - an u32: the nlmsghdr->nlmsg_len member > > When building with -Wsign-compare, this macro triggers a signed compare > warning. This is because it compares len to an int, and then compares > it to a u32. If len is signed, we get a warning due to the last test. > If len is unsigned, we get a warning due to the first test. Like in > strace: > socketutils.c:145:8: warning: comparison between signed and unsigned > integer expressions [-Wsign-compare] > > Lets drop the int cast on the first sizeof. This way, once the user > casts len to an unsigned value, everything shakes out correctly. > > Signed-off-by: Mike Frysinger <[email protected]> I don't think we can change this. If you get rid of the 'int' cast then code is going to end up with a signed comparison for the first test even if 'len' is signed, and that's a potential security issue. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
