diff options
author | Olaf Kirch <okir@suse.de> | 2015-10-30 10:18:20 -0400 |
---|---|---|
committer | Steve Dickson <steved@redhat.com> | 2015-10-30 10:18:20 -0400 |
commit | d5dace219953c45d26ae42db238052b68540649a (patch) | |
tree | a3adcb9bfb8649d625c9f705fc2ddeb510381512 | |
parent | de47f6323d8fb20feefee21d0195cf0529151e04 (diff) | |
download | rpcbind-d5dace219953c45d26ae42db238052b68540649a.tar.gz |
Fix memory corruption in PMAP_CALLIT code
- A PMAP_CALLIT call comes in on IPv4 UDP
- rpcbind duplicates the caller's address to a netbuf and stores it in
FINFO[0].caller_addr. caller_addr->buf now points to a memory region A
with a size of 16 bytes
- rpcbind forwards the call to the local service, receives a reply
- when processing the reply, it does this in xprt_set_caller:
xprt->xp_rtaddr = *FINFO[0].caller_addr
It sends out the reply, and then frees the netbuf caller_addr and
caller_addr.buf.
However, it does not clear xp_rtaddr, so xp_rtaddr.buf now refers
to memory region A, which is free.
- When the next call comes in on the UDP/IPv4 socket, svc_dg_recv will
be called, which will set xp_rtaddr to the client's address.
It will reuse the buffer inside xp_rtaddr, ie it will write a
sockaddr_in to region A
Some time down the road, an incoming TCP connection is accepted,
allocating a fresh SVCXPRT. The memory region A is inside the
new SVCXPRT
- While processing the TCP call, another UDP call comes in, again
overwriting region A with the client's address
- TCP client closes connection. In svc_destroy, we now trip over
the garbage left in region A
We ran into the case where a commercial scanner was triggering
occasional rpcbind segfaults. The core file that was captured showed
a corrupted xprt->xp_netid pointer that was really a sockaddr_in.
Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Steve Dickson <steved@redhat.com>
-rw-r--r-- | src/rpcb_svc_com.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/src/rpcb_svc_com.c b/src/rpcb_svc_com.c index ff9ce6b..4ae93f1 100644 --- a/src/rpcb_svc_com.c +++ b/src/rpcb_svc_com.c @@ -1183,12 +1183,33 @@ check_rmtcalls(struct pollfd *pfds, int nfds) return (ncallbacks_found); } +/* + * This is really a helper function defined in libtirpc, + * but unfortunately, it hasn't been exported yet. + */ +static struct netbuf * +__rpc_set_netbuf(struct netbuf *nb, const void *ptr, size_t len) +{ + if (nb->len != len) { + if (nb->len) + mem_free(nb->buf, nb->len); + nb->buf = mem_alloc(len); + if (nb->buf == NULL) + return NULL; + + nb->maxlen = nb->len = len; + } + memcpy(nb->buf, ptr, len); + return nb; +} + static void xprt_set_caller(SVCXPRT *xprt, struct finfo *fi) { + const struct netbuf *caller = fi->caller_addr; u_int32_t *xidp; - *(svc_getrpccaller(xprt)) = *(fi->caller_addr); + __rpc_set_netbuf(svc_getrpccaller(xprt), caller->buf, caller->len); xidp = __rpcb_get_dg_xidp(xprt); *xidp = fi->caller_xid; } |