Miklos Szeredi 8ba69ba6a3 net: unix: fix sending fds in multiple buffers ... Kalle Olavi Niemitalo reported that: "..., when one process calls sendmsg once to send 43804 bytes of data and one file descriptor, and another process then calls recvmsg three times to receive the 16032+16032+11740 bytes, each of those recvmsg calls returns the file descriptor in the ancillary data. I confirmed this with strace. The behaviour differs from Linux 2.6.26, where reportedly only one of those recvmsg calls (I think the first one) returned the file descriptor." This bug was introduced by a patch from me titled "net: unix: fix inflight counting bug in garbage collector", commit 6209344f5. And the reason is, quoting Kalle: "Before your patch, unix_attach_fds() would set scm->fp = NULL, so that if the loop in unix_stream_sendmsg() ran multiple iterations, it could not call unix_attach_fds() again. But now, unix_attach_fds() leaves scm->fp unchanged, and I think this causes it to be called multiple times and duplicate the same file descriptors to each struct sk_buff." Fix this by introducing a flag that is cleared at the start and set when the fds attached to the first buffer. The resulting code should work equivalently to the one on 2.6.26. Reported-by: Kalle Olavi Niemitalo <kon@iki.fi> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net>		2009-09-11 11:31:45 -07:00
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af_unix.c
garbage.c
Kconfig
Makefile
sysctl_net_unix.c