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authorCyrill Gorcunov <gorcunov@gmail.com>2017-02-27 14:27:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-27 18:43:45 -0800
commitc857ab640c0cddf451cf743f1b70f9ad7f103090 (patch)
treea0ef949cbc801e03f37f62181d04e4c5b7326e2a /fs
parente3b5a342ab9643b4079c8d417d90519388469341 (diff)
downloadlinux-c857ab640c0cddf451cf743f1b70f9ad7f103090.tar.bz2
fs,eventpoll: don't test for bitfield with stack value
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. Link: http://lkml.kernel.org/r/20170214154935.GG1850@uranus.lan Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Vagin <avagin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/eventpoll.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index bcb68fcc8445..5ec16313da1a 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1895,7 +1895,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
* 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) ||