Merge tag 'v5.16-rc2' into devel

Linux 5.16-rc2 is needed because nonurgent fixes headed
for next are strongly textually dependent on a fix that
was applied for rc2.

Signed-off-by: Linus Walleij <[email protected]>

1 files changed, 13 insertions, 3 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f9139dc1262c..88de94da596b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3812,6 +3812,18 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		iter->fmt[i] = '\0';
 		trace_seq_vprintf(&iter->seq, iter->fmt, ap);
 
+		/*
+		 * If iter->seq is full, the above call no longer guarantees
+		 * that ap is in sync with fmt processing, and further calls
+		 * to va_arg() can return wrong positional arguments.
+		 *
+		 * Ensure that ap is no longer used in this case.
+		 */
+		if (iter->seq.full) {
+			p = "";
+			break;
+		}
+
 		if (star)
 			len = va_arg(ap, int);
 
@@ -6706,9 +6718,7 @@ waitagain:
 		cnt = PAGE_SIZE - 1;
 
 	/* reset all but tr, trace, and overruns */
-	memset(&iter->seq, 0,
-	       sizeof(struct trace_iterator) -
-	       offsetof(struct trace_iterator, seq));
+	memset_startat(iter, 0, seq);
 	cpumask_clear(iter->started);
 	trace_seq_init(&iter->seq);
 	iter->pos = -1;