signal: fix __send_signal() false positive kmemcheck warning

This false positive is due to field padding in struct sigqueue. When
this dynamically allocated structure is copied to the stack (in arch-
specific delivery code), kmemcheck sees a read from the padding, which
is, naturally, uninitialized.

Hide the false positive using the __GFP_NOTRACK_FALSE_POSITIVE flag.
Also made the rlimit override code a bit clearer by introducing a new
variable.

Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 809a228019ad..d81f4952eebb 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -832,6 +832,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 {
         struct sigpending *pending;
         struct sigqueue *q;
+        int override_rlimit;
 
         trace_sched_signal_send(sig, t);
 
@@ -863,9 +864,13 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
            make sure at least one signal gets delivered and don't
            pass on the info struct.  */
 
-        q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
-                                             (is_si_special(info) ||
-                                              info->si_code >= 0)));
+        if (sig < SIGRTMIN)
+                override_rlimit = (is_si_special(info) || info->si_code >= 0);
+        else
+                override_rlimit = 0;
+
+        q = __sigqueue_alloc(t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
+                override_rlimit);
         if (q) {
                 list_add_tail(&q->list, &pending->list);
                 switch ((unsigned long) info) {