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 <[email protected]> Signed-off-by: Ian Kent <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
vieko · Mar 8, 2019 · 660c9fc · 660c9fc
1 parent 874d22d
commit 660c9fc
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h
@@ -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;
 }