On May 5, 2014, at 4:10 PM, Pedro Giffuni <p...@freebsd.org> wrote: > El 5/5/2014 4:21 PM, David Chisnall escribió: >> On 5 May 2014, at 20:49, Pedro Giffuni <p...@freebsd.org> wrote: >> >>> Yes, but I reverted it because there are other ways to check for overflows >>> without the performance hit. >> > > FWIW, in this particular case I think the overflow simply doesn't happen: > apparently it is easier to be hit by a DoS first. > > >> Do we have a good reusable routine for doing this somewhere? Clang and gcc >> both have some idiom recognisers that try to spot when people are attempting >> to do this. Clang also has a builtin, which would be good to use when >> available. Overflow checking is very cheap on modern CPUs (add, branch on >> carry), so it would be nice if we could start looking for this malloc() and >> realloc() pattern and replacing the multiply with something that checks for >> the error. >> > > We don't. OpenBSD introduced an extension: reallocarray().
We do. reallocf(), which first appeared in FreeBSD 3.0. Warner _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
