ASoC: msm: qdsp6v2: check for buffer size before read

Check for debugfs ops buf size passed before reading
to eliminate the possibility of reading out of bounds.

Bug: 77528653
Change-Id: I28fd60ce93256b6b0bad62b449092a891cc15463
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>
CVE-2018-5858
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>
diff --git a/sound/soc/msm/qdsp6v2/q6asm.c b/sound/soc/msm/qdsp6v2/q6asm.c
index 3dcefd3..92de033 100755
--- a/sound/soc/msm/qdsp6v2/q6asm.c
+++ b/sound/soc/msm/qdsp6v2/q6asm.c
@@ -137,6 +137,11 @@
 		pr_err("%s: out_buffer is null\n", __func__);
 		return 0;
 	}
+	if (count < OUT_BUFFER_SIZE) {
+		pr_err("%s: read size %d exceeds buf size %zd\n", __func__,
+						OUT_BUFFER_SIZE, count);
+		return 0;
+	}
 	snprintf(out_buffer, OUT_BUFFER_SIZE, "%ld,%ld,%ld,%ld,%ld,%ld,",\
 		out_cold_tv.tv_sec, out_cold_tv.tv_usec, out_warm_tv.tv_sec,\
 		out_warm_tv.tv_usec, out_cont_tv.tv_sec, out_cont_tv.tv_usec);
@@ -186,6 +191,11 @@
 		pr_err("%s: in_buffer is null\n", __func__);
 		return 0;
 	}
+	if (count < IN_BUFFER_SIZE) {
+		pr_err("%s: read size %d exceeds buf size %zd\n", __func__,
+						IN_BUFFER_SIZE, count);
+		return 0;
+	}
 	snprintf(in_buffer, IN_BUFFER_SIZE, "%ld,%ld,",\
 				in_cont_tv.tv_sec, in_cont_tv.tv_usec);
 	return  simple_read_from_buffer(buf, IN_BUFFER_SIZE, ppos,