seize: Fix size error in creds_dumpable()

The goal of this function is to compare everything except caps,
but caps size is took to compare. It's wrong, there must be
used offsetof(struct proc_status_creds, cap_inh) instead.

Also, sigpnd may be different too.

v3: Move excluding sigpnd from comparation in this patch (was in another patch).
    Reorder fields in seize_task_status().
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

compel/include/uapi/infect.h

@@ -16,10 +16,10 @@
 extern int compel_interrupt_task(int pid);
 
 struct seize_task_status {
-	char			state;
-	int			ppid;
 	unsigned long long	sigpnd;
 	unsigned long long	shdpnd;
+	char			state;
+	int			ppid;
 	int			seccomp_mode;
 };
 

criu/seize.c

@@ -629,9 +629,7 @@ static inline bool thread_collected(struct pstree_item *i, pid_t tid)
 static bool creds_dumpable(struct proc_status_creds *parent,
 				struct proc_status_creds *child)
 {
-	const size_t size = sizeof(struct proc_status_creds) -
-			offsetof(struct proc_status_creds, cap_inh);
-
+	size_t size;
 	/*
 	 * The comparison rules are the following
 	 *
@@ -640,17 +638,20 @@ static bool creds_dumpable(struct proc_status_creds *parent,
 	 *    semantic comparison (FIXME) but for
 	 *    now we require them to be exactly
 	 *    identical
+	 *  - sigpnd may be different
 	 *  - the rest of members must match
 	 */
 
-	if (memcmp(parent, child, size)) {
+	size = offsetof(struct proc_status_creds, cap_inh) -
+	       sizeof(parent->s.sigpnd);
+
+	if (memcmp(&parent->s.sigpnd, &child->s.sigpnd, size)) {
 		if (!pr_quelled(LOG_DEBUG)) {
 			pr_debug("Creds undumpable (parent:child)\n"
 				 "  uids:               %d:%d %d:%d %d:%d %d:%d\n"
 				 "  gids:               %d:%d %d:%d %d:%d %d:%d\n"
 				 "  state:              %d:%d"
 				 "  ppid:               %d:%d\n"
-				 "  sigpnd:             %llu:%llu\n"
 				 "  shdpnd:             %llu:%llu\n"
 				 "  seccomp_mode:       %d:%d\n"
 				 "  last_filter:        %u:%u\n",
@@ -664,7 +665,6 @@ static bool creds_dumpable(struct proc_status_creds *parent,
 				 parent->gids[3], child->gids[3],
 				 parent->s.state, child->s.state,
 				 parent->s.ppid, child->s.ppid,
-				 parent->s.sigpnd, child->s.sigpnd,
 				 parent->s.shdpnd, child->s.shdpnd,
 				 parent->s.seccomp_mode, child->s.seccomp_mode,
 				 parent->last_filter, child->last_filter);