linux-hardening - [PATCH] octeontx2-af: replace deprecated strncpy with strscpy

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Message-ID: <20231010-strncpy-drivers-net-ethernet-marvell-octeontx2-af-cgx-c-v1-1-a443e18f9de8@google.com>
Date: Tue, 10 Oct 2023 21:38:11 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Sunil Goutham <sgoutham@...vell.com>, Linu Cherian <lcherian@...vell.com>, 
	Geetha sowjanya <gakula@...vell.com>, Jerin Jacob <jerinj@...vell.com>, hariprasad <hkelam@...vell.com>, 
	Subbaraya Sundeep <sbhatta@...vell.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] octeontx2-af: replace deprecated strncpy with strscpy

`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We can see that linfo->lmac_type is expected to be NUL-terminated based
on the `... - 1`'s present in the current code. Presumably making room
for a NUL-byte at the end of the buffer.

Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.

Let's also prefer the more idiomatic strscpy usage of (dest, src,
sizeof(dest)) rather than (dest, src, SOME_LEN).

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: build-tested only.
---
 drivers/net/ethernet/marvell/octeontx2/af/cgx.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/cgx.c b/drivers/net/ethernet/marvell/octeontx2/af/cgx.c
index e06f77ad6106..6c70c8498690 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/cgx.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/cgx.c
@@ -1218,8 +1218,6 @@ static inline void link_status_user_format(u64 lstat,
 					   struct cgx_link_user_info *linfo,
 					   struct cgx *cgx, u8 lmac_id)
 {
-	const char *lmac_string;
-
 	linfo->link_up = FIELD_GET(RESP_LINKSTAT_UP, lstat);
 	linfo->full_duplex = FIELD_GET(RESP_LINKSTAT_FDUPLEX, lstat);
 	linfo->speed = cgx_speed_mbps[FIELD_GET(RESP_LINKSTAT_SPEED, lstat)];
@@ -1230,12 +1228,12 @@ static inline void link_status_user_format(u64 lstat,
 	if (linfo->lmac_type_id >= LMAC_MODE_MAX) {
 		dev_err(&cgx->pdev->dev, "Unknown lmac_type_id %d reported by firmware on cgx port%d:%d",
 			linfo->lmac_type_id, cgx->cgx_id, lmac_id);
-		strncpy(linfo->lmac_type, "Unknown", LMACTYPE_STR_LEN - 1);
+		strscpy(linfo->lmac_type, "Unknown", sizeof(linfo->lmac_type));
 		return;
 	}
 
-	lmac_string = cgx_lmactype_string[linfo->lmac_type_id];
-	strncpy(linfo->lmac_type, lmac_string, LMACTYPE_STR_LEN - 1);
+	strscpy(linfo->lmac_type, cgx_lmactype_string[linfo->lmac_type_id],
+		sizeof(linfo->lmac_type));
 }
 
 /* Hardware event handlers */

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231010-strncpy-drivers-net-ethernet-marvell-octeontx2-af-cgx-c-529077646c6a

Best regards,
--
Justin Stitt <justinstitt@...gle.com>