From: Arnd Bergmann <arnd@xxxxxxxx>
gcc-10 warns about a strncpy() that does not enforce zero-termination:
In file included from include/linux/string.h:369,
from drivers/staging/greybus/fw-management.c:9:
In function 'strncpy',
inlined from 'fw_mgmt_backend_fw_update_operation' at drivers/staging/greybus/fw-management.c:306:2:
include/linux/fortify-string.h:108:30: error: '__builtin_strncpy' specified bound 10 equals destination size [-Werror=stringop-truncation]
108 | #define __underlying_strncpy __builtin_strncpy
| ^
include/linux/fortify-string.h:187:9: note: in expansion of macro '__underlying_strncpy'
187 | return __underlying_strncpy(p, q, size);
| ^~~~~~~~~~~~~~~~~~~~
For some reason, I cannot reproduce this with gcc-9 or gcc-11, and I only
get a warning for one of the four related strncpy()s, so I'm not
sure what's going on.
Change all four to strscpy_pad(), which is the safest replacement here,
as it avoids ending up with uninitialized stack data in the tag name.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
v2
- use strscpy_pad()
- use two-argument form
- change all four instances, not just the one that produced the warning
---
drivers/staging/greybus/fw-management.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c
index 3054f084d777..a47385175582 100644
--- a/drivers/staging/greybus/fw-management.c
+++ b/drivers/staging/greybus/fw-management.c
@@ -123,8 +123,7 @@ static int fw_mgmt_interface_fw_version_operation(struct fw_mgmt *fw_mgmt,
fw_info->major = le16_to_cpu(response.major);
fw_info->minor = le16_to_cpu(response.minor);
- strncpy(fw_info->firmware_tag, response.firmware_tag,
- GB_FIRMWARE_TAG_MAX_SIZE);
+ strscpy_pad(fw_info->firmware_tag, response.firmware_tag);
/*
* The firmware-tag should be NULL terminated, otherwise throw error but
@@ -153,7 +152,7 @@ static int fw_mgmt_load_and_validate_operation(struct fw_mgmt *fw_mgmt,
}
request.load_method = load_method;
- strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);
+ strscpy_pad(request.firmware_tag, tag);
/*
* The firmware-tag should be NULL terminated, otherwise throw error and
@@ -249,8 +248,7 @@ static int fw_mgmt_backend_fw_version_operation(struct fw_mgmt *fw_mgmt,
struct gb_fw_mgmt_backend_fw_version_response response;
int ret;
- strncpy(request.firmware_tag, fw_info->firmware_tag,
- GB_FIRMWARE_TAG_MAX_SIZE);
+ strscpy_pad(request.firmware_tag, fw_info->firmware_tag);
/*
* The firmware-tag should be NULL terminated, otherwise throw error and
@@ -303,13 +301,13 @@ static int fw_mgmt_backend_fw_update_operation(struct fw_mgmt *fw_mgmt,
struct gb_fw_mgmt_backend_fw_update_request request;
int ret;
- strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);
+ ret = strscpy_pad(request.firmware_tag, tag);
/*
* The firmware-tag should be NULL terminated, otherwise throw error and
* fail.
*/
- if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') {
+ if (ret == -E2BIG) {
dev_err(fw_mgmt->parent, "backend-update: firmware-tag is not NULL terminated\n");
return -EINVAL;
}
--
2.39.2
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