42 строки
1.6 KiB
Diff
42 строки
1.6 KiB
Diff
This is a proposed patch from the security researcher.
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Not upstreamed yet due to unresponsive maintainers.
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https://github.com/lathiat/avahi/pull/330
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From 447affe29991ee99c6b9732fc5f2c1048a611d3b Mon Sep 17 00:00:00 2001
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From: Riccardo Schirone <sirmy15@gmail.com>
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Date: Fri, 26 Mar 2021 11:50:24 +0100
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Subject: [PATCH] Avoid infinite-loop in avahi-daemon by handling HUP event in
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client_work
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If a client fills the input buffer, client_work() disables the
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AVAHI_WATCH_IN event, thus preventing the function from executing the
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`read` syscall the next times it is called. However, if the client then
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terminates the connection, the socket file descriptor receives a HUP
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event, which is not handled, thus the kernel keeps marking the HUP event
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as occurring. While iterating over the file descriptors that triggered
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an event, the client file descriptor will keep having the HUP event and
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the client_work() function is always called with AVAHI_WATCH_HUP but
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without nothing being done, thus entering an infinite loop.
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See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=984938
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---
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avahi-daemon/simple-protocol.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/avahi-daemon/simple-protocol.c b/avahi-daemon/simple-protocol.c
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index 3e0ebb11..6c0274d6 100644
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--- a/avahi-daemon/simple-protocol.c
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+++ b/avahi-daemon/simple-protocol.c
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@@ -424,6 +424,11 @@ static void client_work(AvahiWatch *watch, AVAHI_GCC_UNUSED int fd, AvahiWatchEv
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}
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}
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+ if (events & AVAHI_WATCH_HUP) {
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+ client_free(c);
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+ return;
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+ }
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+
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c->server->poll_api->watch_update(
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watch,
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(c->outbuf_length > 0 ? AVAHI_WATCH_OUT : 0) |
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