Commit 6ee5a399 authored by Dmitri Monakhov's avatar Dmitri Monakhov Committed by Linus Torvalds
Browse files

inotify: fix IN_ONESHOT unmount event watcher

On umount two event will be dispatched to watcher:

1: inotify_dev_queue_event(.., IN_UNMOUNT,..)
2: remove_watch(watch, dev)
    ->inotify_dev_queue_event(.., IN_IGNORED, ..)

But if watcher has IN_ONESHOT bit set then the watcher will be released
inside first event.  Which result in accessing invalid object later.  IMHO
it is not pure regression.  This bug wasn't triggered while initial
inotify interface testing phase because of another bug in IN_ONESHOT
handling logic :)

  commit ac74c00e

  Author: Ulisses Furquim <>
  Date:   Fri Feb 8 04:18:16 2008 -0800
    inotify: fix check for one-shot watches before destroying them
    As the IN_ONESHOT bit is never set when an event is sent we must check it
    in the watch's mask and not in the event's mask.

mkdir mnt
mount -ttmpfs none mnt
mkdir mnt/d
./inotify mnt/d&
umount mnt ## << lockup or crash here

/* gcc -oinotify inotify.c */
#include <stdio.h>
#include <stdlib.h>
#include <sys/inotify.h>

int main(int argc, char **argv)
        char buf[1024];
        struct inotify_event *ie;
        char *p;
        int i;
        ssize_t l;

        p = argv[1];
        i = inotify_init();
        inotify_add_watch(i, p, ~0);

        l = read(i, buf, sizeof(buf));
        printf("read %d bytes\n", l);
        ie = (struct inotify_event *) buf;
        printf("event mask: %d\n", ie->mask);
	return 0;
Signed-off-by: default avatarDmitri Monakhov <>
Cc: John McCutchan <>
Cc: Al Viro <>
Cc: Robert Love <>
Cc: Ulisses Furquim <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent aa6f1479
......@@ -428,11 +428,13 @@ void inotify_unmount_inodes(struct list_head *list)
watches = &inode->inotify_watches;
list_for_each_entry_safe(watch, next_w, watches, i_list) {
struct inotify_handle *ih= watch->ih;
ih->in_ops->handle_event(watch, watch->wd, IN_UNMOUNT, 0,
inotify_remove_watch_locked(ih, watch);
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