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Commit 6c85501f authored by Al Viro's avatar Al Viro
Browse files

fix infoleak in waitid(2) 



kernel_waitid() can return a PID, an error or 0.  rusage is filled in the first
case and waitid(2) rusage should've been copied out exactly in that case, *not*
whenever kernel_waitid() has not returned an error.  Compat variant shares that
braino; none of kernel_wait4() callers do, so the below ought to fix it.

Reported-and-tested-by: default avatarAlexander Potapenko <glider@google.com>
Fixes: ce72a16f ("wait4(2)/waitid(2): separate copying rusage to userland")
Cc: stable@vger.kernel.org # v4.13
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b776e4b1

kernel/exit.c

+10 −13
Original line number Diff line number Diff line
@@ -1600,12 +1600,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 
	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)))

			return -EFAULT;

	}
@@ -1723,9 +1721,7 @@ COMPAT_SYSCALL_DEFINE5(waitid, 
	if (err > 0) {

		signo = SIGCHLD;

		err = 0;

	}



	if (!err && uru) {

		if (uru) {

			/* kernel_waitid() overwrites everything in ru */

			if (COMPAT_USE_64BIT_TIME)

				err = copy_to_user(uru, &ru, sizeof(ru));
@@ -1734,6 +1730,7 @@ COMPAT_SYSCALL_DEFINE5(waitid, 
			if (err)

				return -EFAULT;

		}

	}



	if (!infop)

		return err;