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From: Thorsten Blum <thorsten.blum@linux.dev>
To: Viresh Kumar <vireshk@kernel.org>,
Johan Hovold <johan@kernel.org>,
Alex Elder <elder@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Thorsten Blum <thorsten.blum@linux.dev>,
greybus-dev@lists.linaro.org,
linux-staging@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: [PATCH v2] staging: greybus: Check for string truncation instead of
NUL-termination
Date: Wed, 2 Apr 2025 13:57:54 +0200
Message-ID: <20250402115755.1929043-1-thorsten.blum@linux.dev>
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Commit 18f44de63f88 ("staging: greybus: change strncpy() to
strscpy_pad()") didn't remove the now unnecessary NUL-termination
checks. Unlike strncpy(), strscpy_pad() guarantees that the destination
buffer is NUL-terminated, making these checks obsolete. Remove them and
check for string truncation instead.
Compile-tested only.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Check the return value of strscpy_pad() for string truncation instead
of NUL-termination as suggested by Alex Elder
- Link to v1: https://lore.kernel.org/r/20250331183935.1880097-2-thorsten.b=
lum@linux.dev/
---
drivers/staging/greybus/fw-management.c | 48 +++++++++----------------
1 file changed, 17 insertions(+), 31 deletions(-)
diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/grey=
bus/fw-management.c
index a47385175582..152949c23d65 100644
--- a/drivers/staging/greybus/fw-management.c
+++ b/drivers/staging/greybus/fw-management.c
@@ -123,17 +123,11 @@ static int fw_mgmt_interface_fw_version_operation(str=
uct fw_mgmt *fw_mgmt,
fw_info->major =3D le16_to_cpu(response.major);
fw_info->minor =3D le16_to_cpu(response.minor);
=20
- strscpy_pad(fw_info->firmware_tag, response.firmware_tag);
-
- /*
- * The firmware-tag should be NULL terminated, otherwise throw error but
- * don't fail.
- */
- if (fw_info->firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] !=3D '\0') {
+ ret =3D strscpy_pad(fw_info->firmware_tag, response.firmware_tag);
+ if (ret =3D=3D -E2BIG)
dev_err(fw_mgmt->parent,
- "fw-version: firmware-tag is not NULL terminated\n");
- fw_info->firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] =3D '\0';
- }
+ "fw-version: truncated firmware tag: %s\n",
+ fw_info->firmware_tag);
=20
return 0;
}
@@ -152,14 +146,12 @@ static int fw_mgmt_load_and_validate_operation(struct=
fw_mgmt *fw_mgmt,
}
=20
request.load_method =3D load_method;
- strscpy_pad(request.firmware_tag, tag);
=20
- /*
- * The firmware-tag should be NULL terminated, otherwise throw error and
- * fail.
- */
- if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] !=3D '\0') {
- dev_err(fw_mgmt->parent, "load-and-validate: firmware-tag is not NULL te=
rminated\n");
+ ret =3D strscpy_pad(request.firmware_tag, tag);
+ if (ret =3D=3D -E2BIG) {
+ dev_err(fw_mgmt->parent,
+ "load-and-validate: truncated firmware tag: %s\n",
+ request.firmware_tag);
return -EINVAL;
}
=20
@@ -248,14 +240,11 @@ static int fw_mgmt_backend_fw_version_operation(struc=
t fw_mgmt *fw_mgmt,
struct gb_fw_mgmt_backend_fw_version_response response;
int ret;
=20
- strscpy_pad(request.firmware_tag, fw_info->firmware_tag);
-
- /*
- * The firmware-tag should be NULL terminated, otherwise throw error and
- * fail.
- */
- if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] !=3D '\0') {
- dev_err(fw_mgmt->parent, "backend-version: firmware-tag is not NULL term=
inated\n");
+ ret =3D strscpy_pad(request.firmware_tag, fw_info->firmware_tag);
+ if (ret =3D=3D -E2BIG) {
+ dev_err(fw_mgmt->parent,
+ "backend-fw-version: truncated firmware tag: %s\n",
+ request.firmware_tag);
return -EINVAL;
}
=20
@@ -302,13 +291,10 @@ static int fw_mgmt_backend_fw_update_operation(struct=
fw_mgmt *fw_mgmt,
int ret;
=20
ret =3D strscpy_pad(request.firmware_tag, tag);
-
- /*
- * The firmware-tag should be NULL terminated, otherwise throw error and
- * fail.
- */
if (ret =3D=3D -E2BIG) {
- dev_err(fw_mgmt->parent, "backend-update: firmware-tag is not NULL termi=
nated\n");
+ dev_err(fw_mgmt->parent,
+ "backend-fw-update: truncated firmware tag: %s\n",
+ request.firmware_tag);
return -EINVAL;
}
=20
--=20
2.49.0