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 can see that client->name should be NUL-terminated based on its usage
with a %s C-string format specifier.
| client->thread = kthread_run(ioreq_task, client, "VM%u-%s",
| client->vm->vmid, client->name);
NUL-padding is not required as client is already zero-allocated:
| client = kzalloc(sizeof(*client), 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.
Note that this patch relies on the _new_ 2-argument version of strscpy()
introduced in Commit e6584c3964f2f ("string: Allow 2-argument
strscpy()").
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: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
drivers/virt/acrn/ioreq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/virt/acrn/ioreq.c b/drivers/virt/acrn/ioreq.c
index 29e1ef1915fd..e94358239a4b 100644
--- a/drivers/virt/acrn/ioreq.c
+++ b/drivers/virt/acrn/ioreq.c
@@ -433,7 +433,7 @@ struct acrn_ioreq_client *acrn_ioreq_client_create(struct acrn_vm *vm,
client->priv = priv;
client->is_default = is_default;
if (name)
- strncpy(client->name, name, sizeof(client->name) - 1);
+ strscpy(client->name, name);
rwlock_init(&client->range_lock);
INIT_LIST_HEAD(&client->range_list);
init_waitqueue_head(&client->wq);
---
base-commit: a4145ce1e7bc247fd6f2846e8699473448717b37
change-id: 20240320-strncpy-drivers-virt-acrn-ioreq-c-9913a5c6e2bf
Best regards,
--
Justin Stitt <[email protected]>
On Wed, Mar 20, 2024 at 11:27:09PM +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.
>
> We can see that client->name should be NUL-terminated based on its usage
> with a %s C-string format specifier.
> | client->thread = kthread_run(ioreq_task, client, "VM%u-%s",
> | client->vm->vmid, client->name);
>
> NUL-padding is not required as client is already zero-allocated:
> | client = kzalloc(sizeof(*client), 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.
>
> Note that this patch relies on the _new_ 2-argument version of strscpy()
> introduced in Commit e6584c3964f2f ("string: Allow 2-argument
> strscpy()").
>
> 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: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On Wed, 20 Mar 2024 23:27:09 +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.
>
> We can see that client->name should be NUL-terminated based on its usage
> with a %s C-string format specifier.
> | client->thread = kthread_run(ioreq_task, client, "VM%u-%s",
> | client->vm->vmid, client->name);
>
> [...]
Applied to for-next/hardening, thanks!
[1/1] virt: acrn: replace deprecated strncpy with strscpy
https://git.kernel.org/kees/c/e8a87d0cd048
Take care,
--
Kees Cook