netdev - [PATCH net-next] ptp: ocp: fix sprintf overflow in ptp_ocp

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Message-ID: <20220317075957.GF25237@kili>
Date:   Thu, 17 Mar 2022 10:59:57 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Richard Cochran <richardcochran@...il.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>
Cc:     Richard Cochran <richardcochran@...il.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH net-next] ptp: ocp: fix sprintf overflow in ptp_ocp_verify()

The "chan" value comes from the user via sysfs.  A large like UINT_MAX
could overflow the buffer by three bytes.  Make the buffer larger and
use snprintf() instead of sprintf().

Fixes: 1aa66a3a135a ("ptp: ocp: Program the signal generators via PTP_CLK_REQ_PEROUT")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/ptp/ptp_ocp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 56b04a7bba3a..f0565c4a85df 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -968,15 +968,15 @@ ptp_ocp_verify(struct ptp_clock_info *ptp_info, unsigned pin,
 	       enum ptp_pin_function func, unsigned chan)
 {
 	struct ptp_ocp *bp = container_of(ptp_info, struct ptp_ocp, ptp_info);
-	char buf[16];
+	char buf[20];
 
 	if (func != PTP_PF_PEROUT)
 		return -EOPNOTSUPP;
 
 	if (chan)
-		sprintf(buf, "OUT: GEN%d", chan);
+		snprintf(buf, sizeof(buf), "OUT: GEN%d", chan);
 	else
-		sprintf(buf, "OUT: PHC");
+		snprintf(buf, sizeof(buf), "OUT: PHC");
 
 	return ptp_ocp_sma_store(bp, buf, pin + 1);
 }
-- 
2.20.1