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usermodehelper: don't use CLONE_VFORK for ____call_usermodehelper()

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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>
This commit is contained in:
Oleg Nesterov 2014-12-10 15:54:39 -08:00 committed by Linus Torvalds
parent ddbc22e27e
commit 7117bc8888
1 changed files with 3 additions and 9 deletions
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12
kernel/kmod.c
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@ -223,7 +223,6 @@ static void umh_complete(struct subprocess_info *sub_info)
static int ____call_usermodehelper(void *data) static int ____call_usermodehelper(void *data)
{ {
struct subprocess_info *sub_info = data; struct subprocess_info *sub_info = data;
int wait = sub_info->wait & ~UMH_KILLABLE;
struct cred *new; struct cred *new;
int retval; int retval;
@ -267,7 +266,7 @@ static int ____call_usermodehelper(void *data)
out: out:
sub_info->retval = retval; sub_info->retval = retval;
/* wait_for_helper() will call umh_complete if UHM_WAIT_PROC. */ /* 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); umh_complete(sub_info);
if (!retval) if (!retval)
return 0; return 0;
@ -323,18 +322,13 @@ static void __call_usermodehelper(struct work_struct *work)
{ {
struct subprocess_info *sub_info = struct subprocess_info *sub_info =
container_of(work, struct subprocess_info, work); container_of(work, struct subprocess_info, work);
int wait = sub_info->wait & ~UMH_KILLABLE;
pid_t pid; pid_t pid;
/* CLONE_VFORK: wait until the usermode helper has execve'd if (sub_info->wait & UMH_WAIT_PROC)
* successfully We need the data structures to stay around
* until that is done. */
if (wait == UMH_WAIT_PROC)
pid = kernel_thread(wait_for_helper, sub_info, pid = kernel_thread(wait_for_helper, sub_info,
CLONE_FS | CLONE_FILES | SIGCHLD); CLONE_FS | CLONE_FILES | SIGCHLD);
else { else {
pid = kernel_thread(call_helper, sub_info, pid = kernel_thread(call_helper, sub_info, SIGCHLD);
CLONE_VFORK | SIGCHLD);
/* Worker thread stopped blocking khelper thread. */ /* Worker thread stopped blocking khelper thread. */
kmod_thread_locker = NULL; kmod_thread_locker = NULL;
} }