On Tue, Dec 20, 2016 at 11:31:38AM -0800, Cong Wang wrote: > On Tue, Dec 20, 2016 at 10:17 AM, Dave Jones <da...@codemonkey.org.uk> wrote: > > On Mon, Dec 19, 2016 at 08:36:23PM -0500, David Miller wrote: > > > From: Dave Jones <da...@codemonkey.org.uk> > > > Date: Mon, 19 Dec 2016 19:40:13 -0500 > > > > > > > On Mon, Dec 19, 2016 at 07:31:44PM -0500, Dave Jones wrote: > > > > > > > > > Unfortunately, this made no difference. I spent some time today > > trying > > > > > to make a better reproducer, but failed. I'll revisit again > > tomorrow. > > > > > > > > > > Maybe I need >1 process/thread to trigger this. That would > > explain why > > > > > I can trigger it with Trinity. > > > > > > > > scratch that last part, I finally just repro'd it with a single > > process. > > > > > > Thanks for the info, I'll try to think about this some more. > > > > I threw in some debug printks right before that BUG_ON. > > it's always this: > > > > skb->len=31 skb->data_len=0 offset:30 total_len:9 > > Clearly we fail because 30 > 31 - 2, seems 'offset' is not correct here, > off-by-one?
Ok, I finally made a messy, albeit good enough reproducer. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #define LEN 504 int main(int argc, char* argv[]) { int fd; int zero = 0; char buf[LEN]; memset(buf, 0, LEN); fd = socket(AF_INET6, SOCK_RAW, 7); setsockopt(fd, SOL_IPV6, IPV6_CHECKSUM, &zero, 4); setsockopt(fd, SOL_IPV6, IPV6_DSTOPTS, &buf, LEN); sendto(fd, buf, 1, 0, (struct sockaddr *) buf, 110); }