strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
This pattern of strncpy(dest, src, strlen(src)) is extremely bug-prone.
This pattern basically never results in NUL-terminated destination
strings unless `dest` was zero-initialized. The current implementation
may be accidentally correct as tw_dev is zero-allocated via:
host = scsi_host_alloc(&driver_template, sizeof(TW_Device_Extension));
...
tw_dev = shost_priv(host);
... wherein scsi_host_alloc zero-allocates host:
shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
Also, further suggesting this change is worthwhile is another strscpy()
usage in 32-9xxx.c:
strscpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION,
sizeof(tw_dev->tw_compat_info.driver_version));
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 not be accidentally correct, let's be definitely correct.
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@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
drivers/scsi/3w-sas.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/3w-sas.c b/drivers/scsi/3w-sas.c
index 55989eaa2d9f..9bdb75dfdcd7 100644
--- a/drivers/scsi/3w-sas.c
+++ b/drivers/scsi/3w-sas.c
@@ -1326,7 +1326,8 @@ static int twl_reset_sequence(TW_Device_Extension *tw_dev, int soft_reset)
}
/* Load rest of compatibility struct */
- strncpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION, strlen(TW_DRIVER_VERSION));
+ strscpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION,
+ sizeof(tw_dev->tw_compat_info.driver_version));
tw_dev->tw_compat_info.driver_srl_high = TW_CURRENT_DRIVER_SRL;
tw_dev->tw_compat_info.driver_branch_high = TW_CURRENT_DRIVER_BRANCH;
tw_dev->tw_compat_info.driver_build_high = TW_CURRENT_DRIVER_BUILD;
---
base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c
change-id: 20231023-strncpy-drivers-scsi-3w-sas-c-c7cc037d4bc9
Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>
