Re: [PATCH v4] netlink: Fix autobind race condition that leads to zero port ID
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From: David Miller <davem@davemloft.net>
Date: 2015-09-21 05:55:24
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From: Herbert Xu <herbert@gondor.apana.org.au> Date: Fri, 18 Sep 2015 19:16:50 +0800
The commit c0bb07df7d981e4091432754e30c9c720e2c0c78 ("netlink:
Reset portid after netlink_insert failure") introduced a race
condition where if two threads try to autobind the same socket
one of them may end up with a zero port ID. This led to kernel
deadlocks that were observed by multiple people.
This patch reverts that commit and instead fixes it by introducing
a separte rhash_portid variable so that the real portid is only set
after the socket has been successfully hashed.
Fixes: c0bb07df7d98 ("netlink: Reset portid after netlink_insert failure")
Reported-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>Applied and queued up for -stable, thanks Herbert.