Rainer Weikusat c845acb324 af_unix: Fix splice-bind deadlock ... On 2015/11/06, Dmitry Vyukov reported a deadlock involving the splice system call and AF_UNIX sockets, http://lists.openwall.net/netdev/2015/11/06/24 The situation was analyzed as (a while ago) A: socketpair() B: splice() from a pipe to /mnt/regular_file does sb_start_write() on /mnt C: try to freeze /mnt wait for B to finish with /mnt A: bind() try to bind our socket to /mnt/new_socket_name lock our socket, see it not bound yet decide that it needs to create something in /mnt try to do sb_start_write() on /mnt, block (it's waiting for C). D: splice() from the same pipe to our socket lock the pipe, see that socket is connected try to lock the socket, block waiting for A B: get around to actually feeding a chunk from pipe to file, try to lock the pipe. Deadlock. on 2015/11/10 by Al Viro, http://lists.openwall.net/netdev/2015/11/10/4 The patch fixes this by removing the kern_path_create related code from unix_mknod and executing it as part of unix_bind prior acquiring the readlock of the socket in question. This means that A (as used above) will sb_start_write on /mnt before it acquires the readlock, hence, it won't indirectly block B which first did a sb_start_write and then waited for a thread trying to acquire the readlock. Consequently, A being blocked by C waiting for B won't cause a deadlock anymore (effectively, both A and B acquire two locks in opposite order in the situation described above). Dmitry Vyukov(<dvyukov@google.com>) tested the original patch. Signed-off-by: Rainer Weikusat <rweikusat@mobileactivedefense.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2016-01-04 23:22:49 -05:00
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af_unix.c	af_unix: Fix splice-bind deadlock	2016-01-04 23:22:49 -05:00
diag.c	VFS: net/unix: d_backing_inode() annotations	2015-04-15 15:06:56 -04:00
garbage.c	net: unix: garbage: fixed several comment and whitespace style issues	2015-04-23 13:15:20 -04:00
Kconfig
Makefile
sysctl_net_unix.c