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Merge branch 'work.epoll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

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Pull epoll fixes from Al Viro:
 "Fix reference counting and clean up exit paths"

* 'work.epoll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  do_epoll_ctl(): clean the failure exits up a bit
  epoll: Keep a reference on files added to the check list
This commit is contained in:
Linus Torvalds 2020-08-22 17:11:38 -07:00
commit f320ac6e13
1 changed files with 14 additions and 14 deletions
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28
fs/eventpoll.c
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@ -1994,11 +1994,13 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
* not already there, and calling reverse_path_check() * not already there, and calling reverse_path_check()
* during ep_insert(). * during ep_insert().
*/ */
if (list_empty(&epi->ffd.file->f_tfile_llink)) if (list_empty(&epi->ffd.file->f_tfile_llink)) {
get_file(epi->ffd.file);
list_add(&epi->ffd.file->f_tfile_llink, list_add(&epi->ffd.file->f_tfile_llink,
&tfile_check_list); &tfile_check_list);
} }
} }
}
mutex_unlock(&ep->mtx); mutex_unlock(&ep->mtx);
return error; return error;
@ -2040,6 +2042,7 @@ static void clear_tfile_check_list(void)
file = list_first_entry(&tfile_check_list, struct file, file = list_first_entry(&tfile_check_list, struct file,
f_tfile_llink); f_tfile_llink);
list_del_init(&file->f_tfile_llink); list_del_init(&file->f_tfile_llink);
fput(file);
} }
INIT_LIST_HEAD(&tfile_check_list); INIT_LIST_HEAD(&tfile_check_list);
} }
@ -2200,25 +2203,22 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
full_check = 1; full_check = 1;
if (is_file_epoll(tf.file)) { if (is_file_epoll(tf.file)) {
error = -ELOOP; error = -ELOOP;
if (ep_loop_check(ep, tf.file) != 0) { if (ep_loop_check(ep, tf.file) != 0)
clear_tfile_check_list();
goto error_tgt_fput; goto error_tgt_fput;
} } else {
} else get_file(tf.file);
list_add(&tf.file->f_tfile_llink, list_add(&tf.file->f_tfile_llink,
&tfile_check_list); &tfile_check_list);
error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
if (error) {
out_del:
list_del(&tf.file->f_tfile_llink);
goto error_tgt_fput;
} }
error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
if (error)
goto error_tgt_fput;
if (is_file_epoll(tf.file)) { if (is_file_epoll(tf.file)) {
tep = tf.file->private_data; tep = tf.file->private_data;
error = epoll_mutex_lock(&tep->mtx, 1, nonblock); error = epoll_mutex_lock(&tep->mtx, 1, nonblock);
if (error) { if (error) {
mutex_unlock(&ep->mtx); mutex_unlock(&ep->mtx);
goto out_del; goto error_tgt_fput;
} }
} }
} }
@ -2239,8 +2239,6 @@ out_del:
error = ep_insert(ep, epds, tf.file, fd, full_check); error = ep_insert(ep, epds, tf.file, fd, full_check);
} else } else
error = -EEXIST; error = -EEXIST;
if (full_check)
clear_tfile_check_list();
break; break;
case EPOLL_CTL_DEL: case EPOLL_CTL_DEL:
if (epi) if (epi)
@ -2263,8 +2261,10 @@ out_del:
mutex_unlock(&ep->mtx); mutex_unlock(&ep->mtx);
error_tgt_fput: error_tgt_fput:
if (full_check) if (full_check) {
clear_tfile_check_list();
mutex_unlock(&epmutex); mutex_unlock(&epmutex);
}
fdput(tf); fdput(tf);
error_fput: error_fput: