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commit 6b61ba29c78e26109426429c6d6b354f6e4443cd
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Author: David Mirabito via Linuxptp-devel <linuxptp-devel@lists.sourceforge.net>
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Date: Tue Mar 19 13:42:48 2019 +1100
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Avoid fault when receiving zero length packets
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The manpage for recvmsg says -1 will be returned on error, Zero indicates an
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"orderly shutdown", presumably only in case of stream sockets.
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Further, UNIX Network Programming, Vol 1 says ".. a return value of 0 from
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recvfrom is acceptable for a datagram protocol"
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Such packets have been observed in the wild, aimed at PTP's multicast
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address and port, possibly related to malformed management queries.
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Patch to properly check return from recvmesg and not trigger the fault
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codepath. Instead, such packets are treated as "Bad Message" the same as
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non-zero but still too-short UDP payloads.
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Signed-off-by: David Mirabito <davidjm@arista.com>
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diff --git a/port.c b/port.c
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index ad9554f..9264211 100644
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--- a/port.c
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+++ b/port.c
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@@ -2563,7 +2563,7 @@ static enum fsm_event bc_event(struct port *p, int fd_index)
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msg->hwts.type = p->timestamping;
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cnt = transport_recv(p->trp, fd, msg);
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- if (cnt <= 0) {
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+ if (cnt < 0) {
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pr_err("port %hu: recv message failed", portnum(p));
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msg_put(msg);
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return EV_FAULT_DETECTED;
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diff --git a/sk.c b/sk.c
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index 30162eb..93ba77a 100644
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--- a/sk.c
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+++ b/sk.c
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@@ -359,7 +359,7 @@ int sk_receive(int fd, void *buf, int buflen,
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}
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cnt = recvmsg(fd, &msg, flags);
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- if (cnt < 1)
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+ if (cnt < 0)
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pr_err("recvmsg%sfailed: %m",
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flags == MSG_ERRQUEUE ? " tx timestamp " : " ");
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