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authorVitaly Mayatskikh <v.mayatskih@gmail.com>2009-09-23 15:56:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-24 07:21:00 -0700
commitdfe16dfa4ac178d9a10b489a73d535c6976e48d2 (patch)
tree0ebd7bddf7e99915baed4955faeed2af5bba4203 /kernel
parentb6e763f07fba6243d2a553ed9a4f3e10a789932a (diff)
do_wait: fix sys_waitid()-specific behaviour
do_wait() checks ->wo_info to figure out who is the caller. If it's not NULL the caller should be sys_waitid(), in that case do_wait() fixes up the retval or zeros ->wo_info, depending on retval from underlying function. This is bug: user can pass ->wo_info == NULL and sys_waitid() will return incorrect value. man 2 waitid says: waitid(): returns 0 on success Test-case: int main(void) { if (fork()) assert(waitid(P_ALL, 0, NULL, WEXITED) == 0); return 0; } Result: Assertion `waitid(P_ALL, 0, ((void *)0), 4) == 0' failed. Move that code to sys_waitid(). User-visible change: sys_waitid() will return 0 on success, either infop is set or not. Note, there's another bug in wait_noreap_copyout() which affects return value of sys_waitid(). It will be fixed in next patch. Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/exit.c49
1 files changed, 23 insertions, 26 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 1daa7f46bccd..2cc69eb8db2a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1645,32 +1645,6 @@ notask:
end:
__set_current_state(TASK_RUNNING);
remove_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
-
- if (wo->wo_info) {
- struct siginfo __user *infop = wo->wo_info;
-
- if (retval > 0)
- retval = 0;
- else {
- /*
- * For a WNOHANG return, clear out all the fields
- * we would set so the user can easily tell the
- * difference.
- */
- if (!retval)
- retval = put_user(0, &infop->si_signo);
- if (!retval)
- retval = put_user(0, &infop->si_errno);
- if (!retval)
- retval = put_user(0, &infop->si_code);
- if (!retval)
- retval = put_user(0, &infop->si_pid);
- if (!retval)
- retval = put_user(0, &infop->si_uid);
- if (!retval)
- retval = put_user(0, &infop->si_status);
- }
- }
return retval;
}
@@ -1715,6 +1689,29 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
wo.wo_stat = NULL;
wo.wo_rusage = ru;
ret = do_wait(&wo);
+
+ if (ret > 0) {
+ ret = 0;
+ } else if (infop) {
+ /*
+ * For a WNOHANG return, clear out all the fields
+ * we would set so the user can easily tell the
+ * difference.
+ */
+ if (!ret)
+ ret = put_user(0, &infop->si_signo);
+ if (!ret)
+ ret = put_user(0, &infop->si_errno);
+ if (!ret)
+ ret = put_user(0, &infop->si_code);
+ if (!ret)
+ ret = put_user(0, &infop->si_pid);
+ if (!ret)
+ ret = put_user(0, &infop->si_uid);
+ if (!ret)
+ ret = put_user(0, &infop->si_status);
+ }
+
put_pid(pid);
/* avoid REGPARM breakage on x86: */