| Message ID | 156207955265.1655.13658692984261290810.stgit@warthog.procyon.org.uk |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] rxrpc: Fix send on a connected, but unbound socket | expand |
From: David Howells <dhowells@redhat.com> Date: Tue, 02 Jul 2019 15:59:12 +0100 > If sendmsg() or sendmmsg() is called on a connected socket that hasn't had > bind() called on it, then an oops will occur when the kernel tries to > connect the call because no local endpoint has been allocated. > > Fix this by implicitly binding the socket if it is in the > RXRPC_CLIENT_UNBOUND state, just like it does for the RXRPC_UNBOUND state. > > Further, the state should be transitioned to RXRPC_CLIENT_BOUND after this > to prevent further attempts to bind it. > > This can be tested with: ... > Leading to the following oops: ... > Fixes: 2341e0775747 ("rxrpc: Simplify connect() implementation and simplify sendmsg() op") > Reported-by: syzbot+7966f2a0b2c7da8939b4@syzkaller.appspotmail.com > Signed-off-by: David Howells <dhowells@redhat.com> > Reviewed-by: Marc Dionne <marc.dionne@auristor.com> Applied and queued up for -stable, thanks.
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c index f9f4721cdfa7..d09eaf153544 100644 --- a/net/rxrpc/af_rxrpc.c +++ b/net/rxrpc/af_rxrpc.c @@ -545,6 +545,7 @@ static int rxrpc_sendmsg(struct socket *sock, struct msghdr *m, size_t len) switch (rx->sk.sk_state) { case RXRPC_UNBOUND: + case RXRPC_CLIENT_UNBOUND: rx->srx.srx_family = AF_RXRPC; rx->srx.srx_service = 0; rx->srx.transport_type = SOCK_DGRAM; @@ -569,10 +570,9 @@ static int rxrpc_sendmsg(struct socket *sock, struct msghdr *m, size_t len) } rx->local = local; - rx->sk.sk_state = RXRPC_CLIENT_UNBOUND; + rx->sk.sk_state = RXRPC_CLIENT_BOUND; /* Fall through */ - case RXRPC_CLIENT_UNBOUND: case RXRPC_CLIENT_BOUND: if (!m->msg_name && test_bit(RXRPC_SOCK_CONNECTED, &rx->flags)) {
If sendmsg() or sendmmsg() is called on a connected socket that hasn't had bind() called on it, then an oops will occur when the kernel tries to connect the call because no local endpoint has been allocated. Fix this by implicitly binding the socket if it is in the RXRPC_CLIENT_UNBOUND state, just like it does for the RXRPC_UNBOUND state. Further, the state should be transitioned to RXRPC_CLIENT_BOUND after this to prevent further attempts to bind it. This can be tested with: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/socket.h> #include <arpa/inet.h> #include <linux/rxrpc.h> static const unsigned char inet6_addr[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, 0xac, 0x14, 0x14, 0xaa }; int main(void) { struct sockaddr_rxrpc srx; struct cmsghdr *cm; struct msghdr msg; unsigned char control[16]; int fd; memset(&srx, 0, sizeof(srx)); srx.srx_family = 0x21; srx.srx_service = 0; srx.transport_type = AF_INET; srx.transport_len = 0x1c; srx.transport.sin6.sin6_family = AF_INET6; srx.transport.sin6.sin6_port = htons(0x4e22); srx.transport.sin6.sin6_flowinfo = htons(0x4e22); srx.transport.sin6.sin6_scope_id = htons(0xaa3b); memcpy(&srx.transport.sin6.sin6_addr, inet6_addr, 16); cm = (struct cmsghdr *)control; cm->cmsg_len = CMSG_LEN(sizeof(unsigned long)); cm->cmsg_level = SOL_RXRPC; cm->cmsg_type = RXRPC_USER_CALL_ID; *(unsigned long *)CMSG_DATA(cm) = 0; msg.msg_name = NULL; msg.msg_namelen = 0; msg.msg_iov = NULL; msg.msg_iovlen = 0; msg.msg_control = control; msg.msg_controllen = cm->cmsg_len; msg.msg_flags = 0; fd = socket(AF_RXRPC, SOCK_DGRAM, AF_INET); connect(fd, (struct sockaddr *)&srx, sizeof(srx)); sendmsg(fd, &msg, 0); return 0; } Leading to the following oops: BUG: kernel NULL pointer dereference, address: 0000000000000018 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page ... RIP: 0010:rxrpc_connect_call+0x42/0xa01 ... Call Trace: ? mark_held_locks+0x47/0x59 ? __local_bh_enable_ip+0xb6/0xba rxrpc_new_client_call+0x3b1/0x762 ? rxrpc_do_sendmsg+0x3c0/0x92e rxrpc_do_sendmsg+0x3c0/0x92e rxrpc_sendmsg+0x16b/0x1b5 sock_sendmsg+0x2d/0x39 ___sys_sendmsg+0x1a4/0x22a ? release_sock+0x19/0x9e ? reacquire_held_locks+0x136/0x160 ? release_sock+0x19/0x9e ? find_held_lock+0x2b/0x6e ? __lock_acquire+0x268/0xf73 ? rxrpc_connect+0xdd/0xe4 ? __local_bh_enable_ip+0xb6/0xba __sys_sendmsg+0x5e/0x94 do_syscall_64+0x7d/0x1bf entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: 2341e0775747 ("rxrpc: Simplify connect() implementation and simplify sendmsg() op") Reported-by: syzbot+7966f2a0b2c7da8939b4@syzkaller.appspotmail.com Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Marc Dionne <marc.dionne@auristor.com> --- net/rxrpc/af_rxrpc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)