4.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 6c85501f2fabcfc4fc6ed976543d252c4eaf4be9 upstream.
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: Alexander Potapenko <glider@xxxxxxxxxx>
Fixes: ce72a16fa705 ("wait4(2)/waitid(2): separate copying rusage to userland")
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1601,12 +1601,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_
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;
}
@@ -1724,16 +1722,15 @@ COMPAT_SYSCALL_DEFINE5(waitid,
if (err > 0) {
signo = SIGCHLD;
err = 0;
- }
-
- if (!err && uru) {
- /* kernel_waitid() overwrites everything in ru */
- if (COMPAT_USE_64BIT_TIME)
- err = copy_to_user(uru, &ru, sizeof(ru));
- else
- err = put_compat_rusage(&ru, uru);
- if (err)
- return -EFAULT;
+ if (uru) {
+ /* kernel_waitid() overwrites everything in ru */
+ if (COMPAT_USE_64BIT_TIME)
+ err = copy_to_user(uru, &ru, sizeof(ru));
+ else
+ err = put_compat_rusage(&ru, uru);
+ if (err)
+ return -EFAULT;
+ }
}
if (!infop)