79 lines
2.7 KiB
Diff
79 lines
2.7 KiB
Diff
|
commit 06f7ebb1dade2f0dbf872ea2bedf17cff4734bdd
|
||
|
|
Author: Olaf Kirch <okir () suse de>
|
||
|
|
Date: Thu Aug 6 16:27:20 2015 +0200
|
||
|
|
|
||
|
|
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>
|
||
|
|
|
||
|
|
---
|
||
|
|
src/rpcb_svc_com.c | 23 ++++++++++++++++++++++-
|
||
|
|
1 file changed, 22 insertions(+), 1 deletion(-)
|
||
|
|
|
||
|
|
--- src/rpcb_svc_com.c
|
||
|
|
+++ src/rpcb_svc_com.c
|
||
|
|
@@ -1204,12 +1204,33 @@ check_rmtcalls(struct pollfd *pfds, int
|
||
|
|
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;
|
||
|
|
}
|