diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2014-12-10 23:54:39 (GMT) |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 01:41:16 (GMT) |
| commit | 7117bc8888aff73fb081956afa501edcc85a1552 (patch) | |
| tree | 3d0af7c27c1b62e576aa3d6a59706f224920089d | |
| parent | ddbc22e27e672b6b180757ea1d7f8481dbb88128 (diff) | |
| download | linux-7117bc8888aff73fb081956afa501edcc85a1552.tar.xz | |
usermodehelper: don't use CLONE_VFORK for ____call_usermodehelper()
After "kernel/kmod: fix use-after-free of the sub_infostructure"
CLONE_VFORK in __call_usermodehelper() buys nothing, we rely on on
umh_complete() in ____call_usermodehelper() anyway.
Remove it. This also eliminates the unnecessary sleep/wakeup in the
likely case, and this allows the next change.
While at it, kill the "int wait" locals in ____call_usermodehelper() and
__call_usermodehelper(), they can safely use sub_info->wait.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/kmod.c | 12 |
1 files changed, 3 insertions, 9 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c index 80f7a6d..4621771 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -223,7 +223,6 @@ static void umh_complete(struct subprocess_info *sub_info) static int ____call_usermodehelper(void *data) { struct subprocess_info *sub_info = data; - int wait = sub_info->wait & ~UMH_KILLABLE; struct cred *new; int retval; @@ -267,7 +266,7 @@ static int ____call_usermodehelper(void *data) out: sub_info->retval = retval; /* wait_for_helper() will call umh_complete if UHM_WAIT_PROC. */ - if (wait != UMH_WAIT_PROC) + if (!(sub_info->wait & UMH_WAIT_PROC)) umh_complete(sub_info); if (!retval) return 0; @@ -323,18 +322,13 @@ static void __call_usermodehelper(struct work_struct *work) { struct subprocess_info *sub_info = container_of(work, struct subprocess_info, work); - int wait = sub_info->wait & ~UMH_KILLABLE; pid_t pid; - /* CLONE_VFORK: wait until the usermode helper has execve'd - * successfully We need the data structures to stay around - * until that is done. */ - if (wait == UMH_WAIT_PROC) + if (sub_info->wait & UMH_WAIT_PROC) pid = kernel_thread(wait_for_helper, sub_info, CLONE_FS | CLONE_FILES | SIGCHLD); else { - pid = kernel_thread(call_helper, sub_info, - CLONE_VFORK | SIGCHLD); + pid = kernel_thread(call_helper, sub_info, SIGCHLD); /* Worker thread stopped blocking khelper thread. */ kmod_thread_locker = NULL; } |