83 lines
2.7 KiB
Diff
83 lines
2.7 KiB
Diff
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From d5dace219953c45d26ae42db238052b68540649a Mon Sep 17 00:00:00 2001
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From: Olaf Kirch <okir@suse.de>
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Date: Fri, 30 Oct 2015 10:18:20 -0400
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Subject: [PATCH 2/4] Fix memory corruption in PMAP_CALLIT code
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- A PMAP_CALLIT call comes in on IPv4 UDP
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- rpcbind duplicates the caller's address to a netbuf and stores it in
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FINFO[0].caller_addr. caller_addr->buf now points to a memory region A
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with a size of 16 bytes
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- rpcbind forwards the call to the local service, receives a reply
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- when processing the reply, it does this in xprt_set_caller:
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xprt->xp_rtaddr = *FINFO[0].caller_addr
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It sends out the reply, and then frees the netbuf caller_addr and
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caller_addr.buf.
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However, it does not clear xp_rtaddr, so xp_rtaddr.buf now refers
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to memory region A, which is free.
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- When the next call comes in on the UDP/IPv4 socket, svc_dg_recv will
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be called, which will set xp_rtaddr to the client's address.
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It will reuse the buffer inside xp_rtaddr, ie it will write a
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sockaddr_in to region A
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Some time down the road, an incoming TCP connection is accepted,
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allocating a fresh SVCXPRT. The memory region A is inside the
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new SVCXPRT
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- While processing the TCP call, another UDP call comes in, again
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overwriting region A with the client's address
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- TCP client closes connection. In svc_destroy, we now trip over
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the garbage left in region A
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We ran into the case where a commercial scanner was triggering
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occasional rpcbind segfaults. The core file that was captured showed
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a corrupted xprt->xp_netid pointer that was really a sockaddr_in.
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Signed-off-by: Olaf Kirch <okir@suse.de>
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Signed-off-by: Steve Dickson <steved@redhat.com>
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---
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src/rpcb_svc_com.c | 23 ++++++++++++++++++++++-
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1 file changed, 22 insertions(+), 1 deletion(-)
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diff --git a/src/rpcb_svc_com.c b/src/rpcb_svc_com.c
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index ff9ce6b..4ae93f1 100644
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--- a/src/rpcb_svc_com.c
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+++ b/src/rpcb_svc_com.c
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@@ -1183,12 +1183,33 @@ check_rmtcalls(struct pollfd *pfds, int nfds)
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return (ncallbacks_found);
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}
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+/*
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+ * This is really a helper function defined in libtirpc,
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+ * but unfortunately, it hasn't been exported yet.
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+ */
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+static struct netbuf *
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+__rpc_set_netbuf(struct netbuf *nb, const void *ptr, size_t len)
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+{
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+ if (nb->len != len) {
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+ if (nb->len)
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+ mem_free(nb->buf, nb->len);
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+ nb->buf = mem_alloc(len);
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+ if (nb->buf == NULL)
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+ return NULL;
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+
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+ nb->maxlen = nb->len = len;
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+ }
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+ memcpy(nb->buf, ptr, len);
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+ return nb;
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+}
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+
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static void
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xprt_set_caller(SVCXPRT *xprt, struct finfo *fi)
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{
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+ const struct netbuf *caller = fi->caller_addr;
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u_int32_t *xidp;
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- *(svc_getrpccaller(xprt)) = *(fi->caller_addr);
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+ __rpc_set_netbuf(svc_getrpccaller(xprt), caller->buf, caller->len);
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xidp = __rpcb_get_dg_xidp(xprt);
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*xidp = fi->caller_xid;
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}
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--
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1.8.5.6
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