netlink: Fix autobind race condition that leads to zero port ID

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[ Upstream commit 1f770c0a09 ]

The commit c0bb07df7d ("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: c0bb07df7d ("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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Herbert Xu 2015-09-18 19:16:50 +08:00 • committed by Greg Kroah-Hartman

parent d600176461

commit 4e27762417

2 changed files with 7 additions and 5 deletions

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11

net/netlink/af_netlink.c

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1

net/netlink/af_netlink.h

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