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authorOleg Nesterov <oleg@redhat.com>2014-12-10 23:54:39 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-11 01:41:16 (GMT)
commit7117bc8888aff73fb081956afa501edcc85a1552 (patch)
tree3d0af7c27c1b62e576aa3d6a59706f224920089d
parentddbc22e27e672b6b180757ea1d7f8481dbb88128 (diff)
downloadlinux-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.c12
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;
}