Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > On Wed, Dec 27, 2017 at 7:18 PM, syzbot > <syzbot+4396883fa8c4f64e0175@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > > > syzkaller hit the following crash on > > beacbc68ac3e23821a681adb30b45dc55b17488d > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master > > compiler: gcc (GCC) 7.1.1 20170620 > > .config is attached > > Raw console output is attached. > > C reproducer is attached > > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > > for information about syzkaller reproducers > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: <syzbot+4396883fa8c4f64e0175@xxxxxxxxxxxxxxxxxxxxxxxxx> > > It will help syzbot understand when the bug is fixed. See footer for > > details. > > If you forward the report, please keep this part and the footer. > > +netfilter maintainers > > Here is cleaned reproducer: > > // autogenerated by syzkaller (http://github.com/google/syzkaller) > #include <sys/types.h> > #include <sys/socket.h> > #include <netinet/in.h> > #include <netinet/tcp.h> > #include <linux/if.h> > #include <linux/netfilter_ipv4/ip_tables.h> > > int main() > { > int fd; > > fd = socket(AF_INET, SOCK_STREAM, IPPROTO_IP); > struct ipt_replace opt = {}; > opt.num_counters = 1; > opt.size = -1; > setsockopt(fd, SOL_IP, 0x40, &opt, 0x4); > return 0; > } > > > What happens there is that here: > > struct xt_table_info *xt_alloc_table_info(unsigned int size) > { > ... > if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages) > return NULL; > > size = -1 and SMP_ALIGN(size) = 0, so this still tries to allocate > 4GB+delta bytes. > > I don't understand why this uses SMP_ALIGN since we add 2 pages on > top, it seems that we could just drop SMP_ALIGN and local SMP_ALIGN > definition altogether. Looking at history.git this seems to be a left over from back when iptables allocated size * num_cpus() (and used an SMP_ALIGN based offset for each cpu). So yes, I think we can just toss/drop this. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
