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fix waitid(2) breakage

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We lose the distinction between "found a PID" and "nothing, but that's not
an error" a bit too early in waitid().  Easily fixed, fortunately...

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Fixes: 67d7ddded3 ("waitid(2): leave copyout of siginfo to syscall itself")
Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-07-08 11:26:39 -04:00
parent da029c11e6
commit 634a816095
1 changed files with 12 additions and 5 deletions
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17
kernel/exit.c
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@ -1590,9 +1590,6 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
wo.wo_rusage = ru;
ret = do_wait(&wo);
if (ret > 0)
ret = 0;
put_pid(pid);
return ret;
}
@ -1603,6 +1600,11 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
struct rusage r;
struct waitid_info info = {.status = 0};
long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
int signo = 0;
if (err > 0) {
signo = SIGCHLD;
err = 0;
}
if (!err) {
if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
@ -1612,7 +1614,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
return err;
user_access_begin();
unsafe_put_user(err ? 0 : SIGCHLD, &infop->si_signo, Efault);
unsafe_put_user(signo, &infop->si_signo, Efault);
unsafe_put_user(0, &infop->si_errno, Efault);
unsafe_put_user((short)info.cause, &infop->si_code, Efault);
unsafe_put_user(info.pid, &infop->si_pid, Efault);
@ -1714,6 +1716,11 @@ COMPAT_SYSCALL_DEFINE5(waitid,
struct rusage ru;
struct waitid_info info = {.status = 0};
long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
int signo = 0;
if (err > 0) {
signo = SIGCHLD;
err = 0;
}
if (!err && uru) {
/* kernel_waitid() overwrites everything in ru */
@ -1729,7 +1736,7 @@ COMPAT_SYSCALL_DEFINE5(waitid,
return err;
user_access_begin();
unsafe_put_user(err ? 0 : SIGCHLD, &infop->si_signo, Efault);
unsafe_put_user(signo, &infop->si_signo, Efault);
unsafe_put_user(0, &infop->si_errno, Efault);
unsafe_put_user((short)info.cause, &infop->si_code, Efault);
unsafe_put_user(info.pid, &infop->si_pid, Efault);