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b=H4sIABXOMmUC/x2N0QrCMAxFf2Xk2UDTbiD+ioi4Lp0B6Wqic2Ps3 1d8PBfOPRsYq7DBpdlAeRaTKVegUwPx+cgjowyVwTsfyHmH9tEcy4qDysxqWKYfK9q3lNeK/dt 31C33qupY54ixT3QmCqFNHuppUU6y/IPX274foYe/1oAAAAA= X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1697828377; l=2719; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=T+2bP/VZordKJivg0WULS6xpMGyCh5PEFbjppJMYDyw=; b=wfeBrFDrlPg11uAXCMlr1FrdbFjab3mH++hd8n+V8J6m4i2+5fSu+wTfIKW7ADNr0aV6HkBe9 dAIOowSQjgXD6wkWvunWsFVJIEBXYJV97Ryx0HNqH5J9WFFJxzHyBii X-Mailer: b4 0.12.3 Message-ID: <20231020-strncpy-drivers-power-supply-bq2515x_charger-c-v1-1-46664c6edf78@google.com> Subject: [PATCH] power: supply: bq2515x: replace deprecated strncpy with strscpy From: Justin Stitt To: Sebastian Reichel Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Justin Stitt X-Spam-Status: No, score=-8.4 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Fri, 20 Oct 2023 12:00:16 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780302146899389435 X-GMAIL-MSGID: 1780302146899389435 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 expect bq2515x->model_name to be NUL-terminated based on its usage with sysfs_emit and format strings: val->strval is assigned to bq2515x->model_name in bq2515x_mains_get_property(): | val->strval = bq2515x->model_name; ... then in power_supply_sysfs.c we use value.strval with a format string: | ret = sysfs_emit(buf, "%s\n", value.strval); we assigned value.strval via: | ret = power_supply_get_property(psy, psp, &value); ... which invokes psy->desc->get_property(): | return psy->desc->get_property(psy, psp, val); with bq2515x_mains_get_property(): | static const struct power_supply_desc bq2515x_mains_desc = { ... | .get_property = bq2515x_mains_get_property, Moreover, no NUL-padding is required as bq2515x is zero-allocated in bq2515x_charger.c: | bq2515x = devm_kzalloc(dev, sizeof(*bq2515x), GFP_KERNEL); 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 opt to use the more idiomatic strscpy() usage of (dest, src, sizeof(dest)) as this more closely ties the destination buffer and the length. 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@vger.kernel.org Signed-off-by: Justin Stitt Similar-to: https://lore.kernel.org/all/20231020-strncpy-drivers-power-supply-bq24190_charger-c-v1-1-e896223cb795@google.com/ Reviewed-by: Kees Cook --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/power/supply/bq2515x_charger.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: bb55d7f7f7445abcc8db50e6a65d4315e79f75c7 change-id: 20231020-strncpy-drivers-power-supply-bq2515x_charger-c-cbf1811334f2 Best regards, -- Justin Stitt diff --git a/drivers/power/supply/bq2515x_charger.c b/drivers/power/supply/bq2515x_charger.c index 1dbacc9b015d..b4ea1707304a 100644 --- a/drivers/power/supply/bq2515x_charger.c +++ b/drivers/power/supply/bq2515x_charger.c @@ -1092,7 +1092,7 @@ static int bq2515x_probe(struct i2c_client *client) bq2515x->dev = dev; - strncpy(bq2515x->model_name, id->name, I2C_NAME_SIZE); + strscpy(bq2515x->model_name, id->name, sizeof(bq2515x->model_name)); bq2515x->device_id = id->driver_data;