52 lines
1.6 KiB
Diff
52 lines
1.6 KiB
Diff
From 53908fc2863e375884f3a1f26b9ef5b070982758 Mon Sep 17 00:00:00 2001
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Message-Id: <53908fc2863e375884f3a1f26b9ef5b070982758.1517514213.git.Jim.Somerville@windriver.com>
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From: Cong Wang <xiyou.wangcong@gmail.com>
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Date: Sun, 9 Jul 2017 13:19:55 -0700
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Subject: [PATCH 1/1] mqueue: fix a use-after-free in sys_mq_notify()
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The retry logic for netlink_attachskb() inside sys_mq_notify()
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is nasty and vulnerable:
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1) The sock refcnt is already released when retry is needed
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2) The fd is controllable by user-space because we already
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release the file refcnt
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so we when retry but the fd has been just closed by user-space
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during this small window, we end up calling netlink_detachskb()
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on the error path which releases the sock again, later when
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the user-space closes this socket a use-after-free could be
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triggered.
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Setting 'sock' to NULL here should be sufficient to fix it.
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Reported-by: GeneBlue <geneblue.mail@gmail.com>
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Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
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Cc: Andrew Morton <akpm@linux-foundation.org>
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Cc: Manfred Spraul <manfred@colorfullife.com>
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Cc: stable@kernel.org
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
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---
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ipc/mqueue.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/ipc/mqueue.c b/ipc/mqueue.c
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index b8d4aed..6f973f3 100644
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--- a/ipc/mqueue.c
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+++ b/ipc/mqueue.c
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@@ -1244,8 +1244,10 @@ retry:
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timeo = MAX_SCHEDULE_TIMEOUT;
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ret = netlink_attachskb(sock, nc, &timeo, NULL);
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- if (ret == 1)
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+ if (ret == 1) {
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+ sock = NULL;
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goto retry;
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+ }
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if (ret) {
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sock = NULL;
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nc = NULL;
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--
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1.8.3.1
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