drm/i915/gt: Use scnprintf() for avoiding potential buffer overflow

Commit Message

Takashi Iwai March 11, 2020, 7:32 a.m. UTC

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <[e-mail]>
---
 drivers/gpu/drm/i915/gt/intel_engine_cs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 53ac3f00909a..418547bfe03b 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1381,13 +1381,13 @@  static void intel_engine_print_registers(struct intel_engine_cs *engine,
 			char hdr[160];
 			int len;
 
-			len = snprintf(hdr, sizeof(hdr),
+			len = scnprintf(hdr, sizeof(hdr),
 				       "\t\tActive[%d]: ",
 				       (int)(port - execlists->active));
 			if (!i915_request_signaled(rq)) {
 				struct intel_timeline *tl = get_timeline(rq);
 
-				len += snprintf(hdr + len, sizeof(hdr) - len,
+				len += scnprintf(hdr + len, sizeof(hdr) - len,
 						"ring:{start:%08x, hwsp:%08x, seqno:%08x, runtime:%llums}, ",
 						i915_ggtt_offset(rq->ring->vma),
 						tl ? tl->hwsp_offset : 0,
@@ -1398,7 +1398,7 @@  static void intel_engine_print_registers(struct intel_engine_cs *engine,
 				if (tl)
 					intel_timeline_put(tl);
 			}
-			snprintf(hdr + len, sizeof(hdr) - len, "rq: ");
+			scnprintf(hdr + len, sizeof(hdr) - len, "rq: ");
 			print_request(m, rq, hdr);
 		}
 		for (port = execlists->pending; (rq = *port); port++) {