The patch titled
Subject: usermodehelper: don't use CLONE_VFORK for ____call_usermodehelper()
has been added to the -mm tree. Its filename is
usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kmod.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff -puN kernel/kmod.c~usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper kernel/kmod.c
--- a/kernel/kmod.c~usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper
+++ a/kernel/kmod.c
@@ -223,7 +223,6 @@ static void umh_complete(struct subproce
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
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
{
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;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
kernel-kmod-fix-use-after-free-of-the-sub_info-structure.patch
kernel-kmod-fix-use-after-free-of-the-sub_info-structure-v2.patch
usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper.patch
usermodehelper-kill-the-kmod_thread_locker-logic.patch
linux-next.patch
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