diff mbox series

scsi: 3w-sas: replace deprecated strncpy with strscpy

Message ID 20231023-strncpy-drivers-scsi-3w-sas-c-v1-1-4c40a1e99dfc@google.com
State New
Headers show
Series scsi: 3w-sas: replace deprecated strncpy with strscpy | expand

Commit Message

Justin Stitt Oct. 23, 2023, 7:50 p.m. UTC
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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
 drivers/scsi/3w-sas.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)


---
base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c
change-id: 20231023-strncpy-drivers-scsi-3w-sas-c-c7cc037d4bc9

Best regards,
--
Justin Stitt <justinstitt@google.com>

Comments

Martin K. Petersen Nov. 15, 2023, 1:58 p.m. UTC | #1
Justin,

> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.

Applied to 6.8/scsi-staging, thanks!
Martin K. Petersen Nov. 25, 2023, 2:54 a.m. UTC | #2
On Mon, 23 Oct 2023 19:50:57 +0000, Justin Stitt wrote:

> 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:
> 
> [...]

Applied to 6.8/scsi-queue, thanks!

[1/1] scsi: 3w-sas: replace deprecated strncpy with strscpy
      https://git.kernel.org/mkp/scsi/c/7936a19e944b
diff mbox series

Patch

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;