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| author | Cyrill Gorcunov <gorcunov@gmail.com> | 2017-02-27 14:27:40 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-27 18:43:45 -0800 |
| commit | c857ab640c0cddf451cf743f1b70f9ad7f103090 (patch) | |
| tree | a0ef949cbc801e03f37f62181d04e4c5b7326e2a | |
| parent | e3b5a342ab9643b4079c8d417d90519388469341 (diff) | |
| download | linux-stable-c857ab640c0cddf451cf743f1b70f9ad7f103090.tar.gz linux-stable-c857ab640c0cddf451cf743f1b70f9ad7f103090.tar.bz2 linux-stable-c857ab640c0cddf451cf743f1b70f9ad7f103090.zip | |
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>
| -rw-r--r-- | fs/eventpoll.c | 2 |
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) || |