Commit 660c9fc7 authored Mar 07, 2019 by NeilBrown Committed by Linus Torvalds Mar 07, 2019

autofs: clear O_NONBLOCK on the pipe

autofs does not expect the pipe it is given to have O_NONBLOCK set -
specifically if __kernel_write() in autofs_write() returns -EAGAIN, this
is treated as a fatal error and the pipe is closed.

For safety autofs should, therefore, clear the O_NONBLOCK flag.

Releases of systemd prior to 8th February 2019 used
  pipe2(p, O_NONBLOCK|O_CLOEXEC)
and thus (inadvertently) set this flag.

Link: http://lkml.kernel.org/r/154993550902.3321.1183632970046073478.stgit@pluto-themaw-net


Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 874d22d6

fs/autofs/autofs_i.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -216,6 +216,8 @@ static inline int autofs_prepare_pipe(struct file *pipe)
		return -EINVAL;
		/* We want a packet pipe */
		pipe->f_flags \|= O_DIRECT;
		/* We don't expect -EAGAIN */
		pipe->f_flags &= ~O_NONBLOCK;
		return 0;
		}

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