Commit dfe16dfa4ac178d9a10b489a73d535c6976e48d2
Committed by
Linus Torvalds
Linus Torvalds
1 parent
b6e763f07f
Exists in
master
and in
39 other branches
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>
Showing 1 changed file with 23 additions and 26 deletions Side-by-side Diff
kernel/exit.c
| ... | ... | @@ -1645,32 +1645,6 @@ |
| 1645 | 1645 | end: |
| 1646 | 1646 | __set_current_state(TASK_RUNNING); |
| 1647 | 1647 | remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| 1648 | - | |
| 1649 | - if (wo->wo_info) { | |
| 1650 | - struct siginfo __user *infop = wo->wo_info; | |
| 1651 | - | |
| 1652 | - if (retval > 0) | |
| 1653 | - retval = 0; | |
| 1654 | - else { | |
| 1655 | - /* | |
| 1656 | - * For a WNOHANG return, clear out all the fields | |
| 1657 | - * we would set so the user can easily tell the | |
| 1658 | - * difference. | |
| 1659 | - */ | |
| 1660 | - if (!retval) | |
| 1661 | - retval = put_user(0, &infop->si_signo); | |
| 1662 | - if (!retval) | |
| 1663 | - retval = put_user(0, &infop->si_errno); | |
| 1664 | - if (!retval) | |
| 1665 | - retval = put_user(0, &infop->si_code); | |
| 1666 | - if (!retval) | |
| 1667 | - retval = put_user(0, &infop->si_pid); | |
| 1668 | - if (!retval) | |
| 1669 | - retval = put_user(0, &infop->si_uid); | |
| 1670 | - if (!retval) | |
| 1671 | - retval = put_user(0, &infop->si_status); | |
| 1672 | - } | |
| 1673 | - } | |
| 1674 | 1648 | return retval; |
| 1675 | 1649 | } |
| 1676 | 1650 | |
| ... | ... | @@ -1715,6 +1689,29 @@ |
| 1715 | 1689 | wo.wo_stat = NULL; |
| 1716 | 1690 | wo.wo_rusage = ru; |
| 1717 | 1691 | ret = do_wait(&wo); |
| 1692 | + | |
| 1693 | + if (ret > 0) { | |
| 1694 | + ret = 0; | |
| 1695 | + } else if (infop) { | |
| 1696 | + /* | |
| 1697 | + * For a WNOHANG return, clear out all the fields | |
| 1698 | + * we would set so the user can easily tell the | |
| 1699 | + * difference. | |
| 1700 | + */ | |
| 1701 | + if (!ret) | |
| 1702 | + ret = put_user(0, &infop->si_signo); | |
| 1703 | + if (!ret) | |
| 1704 | + ret = put_user(0, &infop->si_errno); | |
| 1705 | + if (!ret) | |
| 1706 | + ret = put_user(0, &infop->si_code); | |
| 1707 | + if (!ret) | |
| 1708 | + ret = put_user(0, &infop->si_pid); | |
| 1709 | + if (!ret) | |
| 1710 | + ret = put_user(0, &infop->si_uid); | |
| 1711 | + if (!ret) | |
| 1712 | + ret = put_user(0, &infop->si_status); | |
| 1713 | + } | |
| 1714 | + | |
| 1718 | 1715 | put_pid(pid); |
| 1719 | 1716 | |
| 1720 | 1717 | /* avoid REGPARM breakage on x86: */ |