Hi all,
there seems to be a regression which allows you to bind the same port twice when the first bind call bound to all ip addresses (i. e. dual stack).
A second bind call for the same port will succeed if you try to bind to a specific ipv4 (e. g. 127.0.0.1), binding to 0.0.0.0 or an ipv6 address fails correctly with EADDRINUSE.
I included a small c program below to show the issue. Normally the second bind call should fail, this was the case before v6.1.
I bisected the regression to commit 5456262d2baa ("net: Fix incorrect address comparison when searching for a bind2 bucket").
I also checked that the issue is still present in v6.3-rc1.
Original report: https://github.com/containers/podman/issues/17719
#regzbot introduced: 5456262d2baa
```
#include <sys/socket.h> #include <sys/un.h> #include <stdlib.h> #include <stdio.h> #include <netinet/in.h> #include <unistd.h>
int main(int argc, char *argv[]) { int ret, sock1, sock2; struct sockaddr_in6 addr; struct sockaddr_in addr2;
sock1 = socket(AF_INET6, SOCK_STREAM, 0); if (sock1 == -1) { perror("socket1"); exit(1); } sock2 = socket(AF_INET, SOCK_STREAM, 0); if (sock2 == -1) { perror("socket2"); exit(1); }
memset(&addr, 0, sizeof(addr)); addr.sin6_family = AF_INET6; addr.sin6_addr = in6addr_any; addr.sin6_port = htons(8080);
memset(&addr2, 0, sizeof(addr2)); addr2.sin_family = AF_INET; addr2.sin_addr.s_addr = htonl(INADDR_LOOPBACK); addr2.sin_port = htons(8080);
ret = bind(sock1, (struct sockaddr *)&addr, sizeof(addr)); if (ret == -1) { perror("bind1"); exit(1); } printf("bind1 ret: %d\n", ret);
if ((listen(sock1, 5)) != 0) { perror("listen1"); exit(1); }
ret = bind(sock2, (struct sockaddr *)&addr2, sizeof(addr2)); if (ret == -1) { perror("bind2"); exit(1); } printf("bind2 ret: %d\n", ret);
if ((listen(sock2, 5)) != 0) { perror("listen2"); exit(1); }
// uncomment pause() to see with ss -tlpn the bound ports // pause();
return 0; }
```
Best regards,
Paul