* [PATCH] pstore/blk: replace deprecated strncpy with strscpy
@ 2024-03-28 20:54 Justin Stitt
2024-03-28 22:00 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Justin Stitt @ 2024-03-28 20:54 UTC (permalink / raw)
To: Kees Cook, Tony Luck, Guilherme G. Piccoli
Cc: linux-hardening, linux-kernel, Justin Stitt
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 know that info-device should be NUL-terminated based on its use with
strlen():
| static int __init mtdpstore_init(void)
| {
| int ret;
| struct mtdpstore_context *cxt = &oops_cxt;
| struct pstore_blk_config *info = &cxt->info;
|
| ret = pstore_blk_get_config(info);
| if (unlikely(ret))
| return ret;
|
| if (strlen(info->device) == 0) {
| pr_err("mtd device must be supplied (device name is empty)\n");
...
Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer.
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: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
fs/pstore/blk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index de8cf5d75f34..65b2473e22ff 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -241,7 +241,7 @@ static int __register_pstore_blk(struct pstore_device_info *dev,
/* get information of pstore/blk */
int pstore_blk_get_config(struct pstore_blk_config *info)
{
- strncpy(info->device, blkdev, 80);
+ strscpy(info->device, blkdev);
info->max_reason = max_reason;
info->kmsg_size = check_size(kmsg_size, 4096);
info->pmsg_size = check_size(pmsg_size, 4096);
---
base-commit: 928a87efa42302a23bb9554be081a28058495f22
change-id: 20240328-strncpy-fs-pstore-blk-c-8c1c0c3079f3
Best regards,
--
Justin Stitt <justinstitt@google.com>
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] pstore/blk: replace deprecated strncpy with strscpy
2024-03-28 20:54 [PATCH] pstore/blk: replace deprecated strncpy with strscpy Justin Stitt
@ 2024-03-28 22:00 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2024-03-28 22:00 UTC (permalink / raw)
To: Tony Luck, Guilherme G. Piccoli, Justin Stitt
Cc: Kees Cook, linux-hardening, linux-kernel
On Thu, 28 Mar 2024 20:54:16 +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 know that info-device should be NUL-terminated based on its use with
> strlen():
> | static int __init mtdpstore_init(void)
> | {
> | int ret;
> | struct mtdpstore_context *cxt = &oops_cxt;
> | struct pstore_blk_config *info = &cxt->info;
> |
> | ret = pstore_blk_get_config(info);
> | if (unlikely(ret))
> | return ret;
> |
> | if (strlen(info->device) == 0) {
> | pr_err("mtd device must be supplied (device name is empty)\n");
> ...
>
> [...]
Applied to for-next/pstore, thanks!
[1/1] pstore/blk: replace deprecated strncpy with strscpy
https://git.kernel.org/kees/c/80b735d01bbb
Take care,
--
Kees Cook
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