From: Cyrill Gorcunov <gorcunov@gmail.com>
To: LINUXFS-ML <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linuxfoundation.org>,
Andrey Vagin <avagin@virtuozzo.com>
Subject: [PATCH] fs,eventpoll: Don't test for bitfield with stack value
Date: Tue, 14 Feb 2017 18:49:35 +0300 [thread overview]
Message-ID: <20170214154935.GG1850@uranus.lan> (raw)
In case if epoll_ctl is called with operation EPOLL_CTL_DEL then
@epds.events variable allocated on stack may contain random bits which
we test then for EPOLLEXCLUSIVE. Since currently the test look
like
if (epds.events & EPOLLEXCLUSIVE) {
if (op == EPOLL_CTL_MOD)
goto error_tgt_fput;
if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
(epds.events & ~EPOLLEXCLUSIVE_OK_BITS)))
goto error_tgt_fput;
}
Nothing serious will happen even if epds.events has this bit set,
still better to be on safe side and make sure that we're to test
this bit at all.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
fs/eventpoll.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-ml.git/fs/eventpoll.c
===================================================================
--- linux-ml.git.orig/fs/eventpoll.c
+++ linux-ml.git/fs/eventpoll.c
@@ -1895,7 +1895,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, in
* so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
* Also, we do not currently supported nested exclusive wakeups.
*/
- if (epds.events & EPOLLEXCLUSIVE) {
+ if (ep_op_has_event(op) && (epds.events & EPOLLEXCLUSIVE)) {
if (op == EPOLL_CTL_MOD)
goto error_tgt_fput;
if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
reply other threads:[~2017-02-14 15:49 UTC|newest]
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