[PATCH net v3] ptp: ocp: Fix board ID over-read

The EEPROM board ID is a fixed 13-byte field and is not guaranteed to
contain a NUL terminator. Passing it directly to
devlink_info_version_fixed_put() treats it as a C string and may read
beyond the field.

Format at most OCP_BOARD_ID_LEN bytes into the existing local buffer
before reporting the ID. Use a precision limit because the snprintf()
output size alone does not bound the source string scan.

Fixes: 0cfcdd1ebcfe ("ptp: ocp: add nvmem interface for accessing eeprom")
Cc: [email protected]
Signed-off-by: Ahmad Byagowi <[email protected]>
---
Changes since RFC v2:
- Split the safety fix from the net-next feature series and target net.
- Use the short Fixes hash.
- Reuse the existing devlink info buffer and bound the source scan with
  string precision.
- Limit the change to the board ID over-read.

RFC v2:
https://lore.kernel.org/r/[email protected]/

 drivers/ptp/ptp_ocp.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 35e911f1ad78c..3d26ec1f7b9ec 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -2177,9 +2177,11 @@ ptp_ocp_devlink_info_get(struct devlink *devlink, struct devlink_info_req *req,
 	if (err)
 		return err;
 
+	snprintf(buf, sizeof(buf), "%.*s", OCP_BOARD_ID_LEN,
+		 (const char *)bp->board_id);
 	err = devlink_info_version_fixed_put(req,
 			DEVLINK_INFO_VERSION_GENERIC_BOARD_ID,
-			bp->board_id);
+			buf);
 	if (err)
 		return err;
 
-- 
2.50.1 (Apple Git-155)