Commit c680e41b3a2e944185c74bf60531e3d316d3ecc4
Committed by
Linus Torvalds
1 parent
000a7d66ec
Exists in
ti-lsk-linux-4.1.y
and in
10 other branches
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>
Showing 1 changed file with 2 additions and 1 deletions Side-by-side Diff
fs/eventpoll.c
... | ... | @@ -1852,7 +1852,8 @@ |
1852 | 1852 | goto error_tgt_fput; |
1853 | 1853 | |
1854 | 1854 | /* Check if EPOLLWAKEUP is allowed */ |
1855 | - ep_take_care_of_epollwakeup(&epds); | |
1855 | + if (ep_op_has_event(op)) | |
1856 | + ep_take_care_of_epollwakeup(&epds); | |
1856 | 1857 | |
1857 | 1858 | /* |
1858 | 1859 | * We have to check that the file structure underneath the file descriptor |