linux-kernel - [PATCH] soc: qcom: cmd-db: Drop NUL bytes from debugfs output

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Message-ID: <20230620213703.283583-1-quic_bjorande@quicinc.com>
Date:   Tue, 20 Jun 2023 14:37:03 -0700
From:   Bjorn Andersson <quic_bjorande@...cinc.com>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] soc: qcom: cmd-db: Drop NUL bytes from debugfs output

The debugfs dump of Command DB relies uses %*pEp to print the resource
identifiers, with escaping of non-printable characters.
But p (ESCAPE_NP) does not escape NUL characters, so for identifiers
less than 8 bytes in length the output will retain these.

This does not cause an issue while looking at the dump in the terminal
(no known complaints at least), but when programmatically consuming the
debugfs output the extra characters are unwanted.

Change the fixed 8-byte sizeof() to a dynamic strnlen() to avoid
printing these NUL characters.

Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>
---
 drivers/soc/qcom/cmd-db.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c
index 33856abd560c..34c40368d5b5 100644
--- a/drivers/soc/qcom/cmd-db.c
+++ b/drivers/soc/qcom/cmd-db.c
@@ -284,7 +284,7 @@ static int cmd_db_debugfs_dump(struct seq_file *seq, void *p)
 		ent = rsc_to_entry_header(rsc);
 		for (j = 0; j < le16_to_cpu(rsc->cnt); j++, ent++) {
 			seq_printf(seq, "0x%05x: %*pEp", le32_to_cpu(ent->addr),
-				   (int)sizeof(ent->id), ent->id);
+				   (int)strnlen(ent->id, sizeof(ent->id)), ent->id);

 			len = le16_to_cpu(ent->len);
 			if (len) {
-- 
2.25.1