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| author | Oleg Nesterov <oleg@redhat.com> | 2010-05-26 23:43:04 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 18:12:45 +0200 |
| commit | d47419cd967a4f032a194148a7b08afad32faded (patch) | |
| tree | b330b3adbaf1b2528b663322adff11a2761cb4b4 /kernel/kmod.c | |
| parent | wait_for_helper: SIGCHLD from user-space can lead to use-after-free (diff) | |
| download | linux-d47419cd967a4f032a194148a7b08afad32faded.tar.xz linux-d47419cd967a4f032a194148a7b08afad32faded.zip | |
call_usermodehelper: simplify/fix UMH_NO_WAIT case
__call_usermodehelper(UMH_NO_WAIT) has 2 problems:
- if kernel_thread() fails, call_usermodehelper_freeinfo()
is not called.
- for unknown reason UMH_NO_WAIT has UMH_WAIT_PROC logic,
we spawn yet another thread which waits until the user
mode application exits.
Change the UMH_NO_WAIT code to use ____call_usermodehelper() instead of
wait_for_helper(), and do call_usermodehelper_freeinfo() unconditionally.
We can rely on CLONE_VFORK, do_fork(CLONE_VFORK) until the child exits or
execs.
With or without this patch UMH_NO_WAIT does not report the error if
kernel_thread() fails, this is correct since the caller doesn't wait for
result.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/kmod.c')
| -rw-r--r-- | kernel/kmod.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c index 48daed4c51ba..ad9f2edebd67 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -205,10 +205,7 @@ static int wait_for_helper(void *data) sub_info->retval = ret; } - if (sub_info->wait == UMH_NO_WAIT) - call_usermodehelper_freeinfo(sub_info); - else - complete(sub_info->complete); + complete(sub_info->complete); return 0; } @@ -217,13 +214,13 @@ static void __call_usermodehelper(struct work_struct *work) { struct subprocess_info *sub_info = container_of(work, struct subprocess_info, work); - pid_t pid; enum umh_wait wait = sub_info->wait; + 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 || wait == UMH_NO_WAIT) + if (wait == UMH_WAIT_PROC) pid = kernel_thread(wait_for_helper, sub_info, CLONE_FS | CLONE_FILES | SIGCHLD); else @@ -232,6 +229,7 @@ static void __call_usermodehelper(struct work_struct *work) switch (wait) { case UMH_NO_WAIT: + call_usermodehelper_freeinfo(sub_info); break; case UMH_WAIT_PROC: |