Author: markj Date: Mon Nov 11 20:44:30 2019 New Revision: 354629 URL: https://svnweb.freebsd.org/changeset/base/354629
Log: Fix handling of PIPE_EOF in the direct write path. Suppose a writing thread has pinned its pages and gone to sleep with pipe_map.cnt > 0. Suppose that the thread is woken up by a signal (so error != 0) and the other end of the pipe has simultaneously been closed. In this case, to satisfy the assertion about pipe_map.cnt in pipe_destroy_write_buffer(), we must mark the buffer as empty. Reported by: syzbot+5cce271bf2cb1b1e1...@syzkaller.appspotmail.com Reviewed by: kib Tested by: pho MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D22261 Modified: head/sys/kern/sys_pipe.c Modified: head/sys/kern/sys_pipe.c ============================================================================== --- head/sys/kern/sys_pipe.c Mon Nov 11 19:54:08 2019 (r354628) +++ head/sys/kern/sys_pipe.c Mon Nov 11 20:44:30 2019 (r354629) @@ -970,15 +970,8 @@ retry: goto error1; } - while (wpipe->pipe_map.cnt != 0) { - if (wpipe->pipe_state & PIPE_EOF) { - wpipe->pipe_map.cnt = 0; - pipe_destroy_write_buffer(wpipe); - pipeselwakeup(wpipe); - pipeunlock(wpipe); - error = EPIPE; - goto error1; - } + while (wpipe->pipe_map.cnt != 0 && + (wpipe->pipe_state & PIPE_EOF) == 0) { if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); @@ -993,12 +986,16 @@ retry: break; } - if (wpipe->pipe_state & PIPE_EOF) + if ((wpipe->pipe_state & PIPE_EOF) != 0) { + wpipe->pipe_map.cnt = 0; + pipe_destroy_write_buffer(wpipe); + pipeselwakeup(wpipe); error = EPIPE; - if (error == EINTR || error == ERESTART) + } else if (error == EINTR || error == ERESTART) { pipe_clone_write_buffer(wpipe); - else + } else { pipe_destroy_write_buffer(wpipe); + } pipeunlock(wpipe); KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, ("pipe %p leaked PIPE_DIRECTW", wpipe)); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
