[PATCH 10/11] perf hists: Fix snprintf() in hists__scnprintf_title() UID filter path

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

hists__scnprintf_title() accumulates formatted output into a buffer
using scnprintf() for all filter clauses except the UID filter, which
uses snprintf().  If the buffer fills up and snprintf() returns more
than the remaining space, printed exceeds size and the next 'size -
printed' underflows, causing later scnprintf() calls to write past
the buffer.

Switch the UID filter clause to scnprintf() to match the rest of the
function.

Fixes: 25c312dbf88ca402 ("perf hists: Move hists__scnprintf_title() away from the TUI code")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/hist.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 811d68fa6770c5b7..df978c996b6c2262 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -2963,9 +2963,10 @@ int __hists__scnprintf_title(struct hists *hists, char *bf, size_t size, bool sh
 			   ev_name, sample_freq_str, enable_ref ? ref : " ", nr_events);
 
 
-	if (hists->uid_filter_str)
-		printed += snprintf(bf + printed, size - printed,
-				    ", UID: %s", hists->uid_filter_str);
+	if (hists->uid_filter_str) {
+		printed += scnprintf(bf + printed, size - printed,
+				     ", UID: %s", hists->uid_filter_str);
+	}
 	if (thread) {
 		if (hists__has(hists, thread)) {
 			printed += scnprintf(bf + printed, size - printed,
-- 
2.54.0