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authorNicolas Iooss <nicolas.iooss_linux@m4x.org>2014-09-09 14:50:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-09-10 15:42:12 -0700
commitc680e41b3a2e944185c74bf60531e3d316d3ecc4 (patch)
tree353c92a56dddd7a1d6cbcce0bc9f13c3a33456e3
parent000a7d66ec30898f46869be01ab8205b056385d0 (diff)
downloadlinux-c680e41b3a2e944185c74bf60531e3d316d3ecc4.tar.bz2
eventpoll: fix uninitialized variable in epoll_ctl
When calling epoll_ctl with operation EPOLL_CTL_DEL, structure epds is not initialized but ep_take_care_of_epollwakeup reads its event field. When this unintialized field has EPOLLWAKEUP bit set, a capability check is done for CAP_BLOCK_SUSPEND in ep_take_care_of_epollwakeup. This produces unexpected messages in the audit log, such as (on a system running SELinux): type=AVC msg=audit(1408212798.866:410): avc: denied { block_suspend } for pid=7754 comm="dbus-daemon" capability=36 scontext=unconfined_u:unconfined_r:unconfined_t tcontext=unconfined_u:unconfined_r:unconfined_t tclass=capability2 permissive=1 type=SYSCALL msg=audit(1408212798.866:410): arch=c000003e syscall=233 success=yes exit=0 a0=3 a1=2 a2=9 a3=7fffd4d66ec0 items=0 ppid=1 pid=7754 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=3 comm="dbus-daemon" exe="/usr/bin/dbus-daemon" subj=unconfined_u:unconfined_r:unconfined_t key=(null) ("arch=c000003e syscall=233 a1=2" means "epoll_ctl(op=EPOLL_CTL_DEL)") Remove use of epds in epoll_ctl when op == EPOLL_CTL_DEL. Fixes: 4d7e30d98939 ("epoll: Add a flag, EPOLLWAKEUP, to prevent suspend while epoll events are ready") Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Arve Hjønnevåg <arve@android.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/eventpoll.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index b10b48c2a7af..7bcfff900f05 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1852,7 +1852,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
goto error_tgt_fput;
/* Check if EPOLLWAKEUP is allowed */
- ep_take_care_of_epollwakeup(&epds);
+ if (ep_op_has_event(op))
+ ep_take_care_of_epollwakeup(&epds);
/*
* We have to check that the file structure underneath the file descriptor