[v1] scsi: elx: sli4: Replace deprecated strncpy() with strscpy()

[PATCH] scsi: elx: sli4: Replace deprecated strncpy() with strscpy()

Posted by Thorsten Blum 11 months, 2 weeks ago

strncpy() is deprecated for NUL-terminated destination buffers; use
strscpy() instead.

Compile-tested only.

Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 drivers/scsi/elx/libefc_sli/sli4.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/elx/libefc_sli/sli4.c b/drivers/scsi/elx/libefc_sli/sli4.c
index 5e7fb110bc3f..d9a231fc0e0d 100644
--- a/drivers/scsi/elx/libefc_sli/sli4.c
+++ b/drivers/scsi/elx/libefc_sli/sli4.c
@@ -3804,7 +3804,7 @@ sli_cmd_common_write_object(struct sli4 *sli4, void *buf, u16 noc,
 	wr_obj->desired_write_len_dword = cpu_to_le32(dwflags);
 
 	wr_obj->write_offset = cpu_to_le32(offset);
-	strncpy(wr_obj->object_name, obj_name, sizeof(wr_obj->object_name) - 1);
+	strscpy(wr_obj->object_name, obj_name);
 	wr_obj->host_buffer_descriptor_count = cpu_to_le32(1);
 
 	bde = (struct sli4_bde *)wr_obj->host_buffer_descriptor;
@@ -3833,7 +3833,7 @@ sli_cmd_common_delete_object(struct sli4 *sli4, void *buf, char *obj_name)
 			 SLI4_SUBSYSTEM_COMMON, CMD_V0,
 			 SLI4_RQST_PYLD_LEN(cmn_delete_object));
 
-	strncpy(req->object_name, obj_name, sizeof(req->object_name) - 1);
+	strscpy(req->object_name, obj_name);
 	return 0;
 }
 
@@ -3856,7 +3856,7 @@ sli_cmd_common_read_object(struct sli4 *sli4, void *buf, u32 desired_read_len,
 		cpu_to_le32(desired_read_len & SLI4_REQ_DESIRE_READLEN);
 
 	rd_obj->read_offset = cpu_to_le32(offset);
-	strncpy(rd_obj->object_name, obj_name, sizeof(rd_obj->object_name) - 1);
+	strscpy(rd_obj->object_name, obj_name);
 	rd_obj->host_buffer_descriptor_count = cpu_to_le32(1);
 
 	bde = (struct sli4_bde *)rd_obj->host_buffer_descriptor;
-- 
2.48.1

Re: [PATCH] scsi: elx: sli4: Replace deprecated strncpy() with strscpy()

Posted by Kees Cook 10 months ago

On Wed, Feb 26, 2025 at 07:55:26PM +0100, Thorsten Blum wrote:
> strncpy() is deprecated for NUL-terminated destination buffers; use
> strscpy() instead.
> 
> Compile-tested only.
> 
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>  drivers/scsi/elx/libefc_sli/sli4.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/elx/libefc_sli/sli4.c b/drivers/scsi/elx/libefc_sli/sli4.c
> index 5e7fb110bc3f..d9a231fc0e0d 100644
> --- a/drivers/scsi/elx/libefc_sli/sli4.c
> +++ b/drivers/scsi/elx/libefc_sli/sli4.c
> @@ -3804,7 +3804,7 @@ sli_cmd_common_write_object(struct sli4 *sli4, void *buf, u16 noc,
>  	wr_obj->desired_write_len_dword = cpu_to_le32(dwflags);
>  
>  	wr_obj->write_offset = cpu_to_le32(offset);
> -	strncpy(wr_obj->object_name, obj_name, sizeof(wr_obj->object_name) - 1);
> +	strscpy(wr_obj->object_name, obj_name);

Standard question for these kinds of conversions: Why is it safe that
this is not NUL padded? I haven't found where this buffer is being
zeroed out, but it probably is (given the "- 1" on the length), but
without run-time testing, this needs much more careful analysis.

-Kees

>  	wr_obj->host_buffer_descriptor_count = cpu_to_le32(1);
>  
>  	bde = (struct sli4_bde *)wr_obj->host_buffer_descriptor;
> @@ -3833,7 +3833,7 @@ sli_cmd_common_delete_object(struct sli4 *sli4, void *buf, char *obj_name)
>  			 SLI4_SUBSYSTEM_COMMON, CMD_V0,
>  			 SLI4_RQST_PYLD_LEN(cmn_delete_object));
>  
> -	strncpy(req->object_name, obj_name, sizeof(req->object_name) - 1);
> +	strscpy(req->object_name, obj_name);
>  	return 0;
>  }
>  
> @@ -3856,7 +3856,7 @@ sli_cmd_common_read_object(struct sli4 *sli4, void *buf, u32 desired_read_len,
>  		cpu_to_le32(desired_read_len & SLI4_REQ_DESIRE_READLEN);
>  
>  	rd_obj->read_offset = cpu_to_le32(offset);
> -	strncpy(rd_obj->object_name, obj_name, sizeof(rd_obj->object_name) - 1);
> +	strscpy(rd_obj->object_name, obj_name);
>  	rd_obj->host_buffer_descriptor_count = cpu_to_le32(1);
>  
>  	bde = (struct sli4_bde *)rd_obj->host_buffer_descriptor;
> -- 
> 2.48.1
> 

-- 
Kees Cook

Re: [PATCH] scsi: elx: sli4: Replace deprecated strncpy() with strscpy()

Posted by Thorsten Blum 10 months ago

On 7. Apr 2025, at 20:28, Kees Cook wrote:
> On Wed, Feb 26, 2025 at 07:55:26PM +0100, Thorsten Blum wrote:
>> strncpy() is deprecated for NUL-terminated destination buffers; use
>> strscpy() instead.
>> 
>> Compile-tested only.
>> 
>> Link: https://github.com/KSPP/linux/issues/90
>> Cc: linux-hardening@vger.kernel.org
>> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
>> ---
> 
> Standard question for these kinds of conversions: Why is it safe that
> this is not NUL padded? I haven't found where this buffer is being
> zeroed out, but it probably is (given the "- 1" on the length), but
> without run-time testing, this needs much more careful analysis.

I think this was submitted before I started to explain this better.

'wr_obj' is the zeroed out 'buf' returned from sli_config_cmd_init().

I'll update the description and submit a v2.

Thanks,
Thorsten

Re: [PATCH] scsi: elx: sli4: Replace deprecated strncpy() with strscpy()

Posted by Kees Cook 10 months ago

On Mon, Apr 07, 2025 at 09:01:53PM +0200, Thorsten Blum wrote:
> On 7. Apr 2025, at 20:28, Kees Cook wrote:
> > On Wed, Feb 26, 2025 at 07:55:26PM +0100, Thorsten Blum wrote:
> >> strncpy() is deprecated for NUL-terminated destination buffers; use
> >> strscpy() instead.
> >> 
> >> Compile-tested only.
> >> 
> >> Link: https://github.com/KSPP/linux/issues/90
> >> Cc: linux-hardening@vger.kernel.org
> >> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> >> ---
> > 
> > Standard question for these kinds of conversions: Why is it safe that
> > this is not NUL padded? I haven't found where this buffer is being
> > zeroed out, but it probably is (given the "- 1" on the length), but
> > without run-time testing, this needs much more careful analysis.
> 
> I think this was submitted before I started to explain this better.
> 
> 'wr_obj' is the zeroed out 'buf' returned from sli_config_cmd_init().

I don't see how dma->virt and buf are associated?

> 
> I'll update the description and submit a v2.

Thanks!

> 
> Thanks,
> Thorsten
> 

-- 
Kees Cook

Re: [PATCH] scsi: elx: sli4: Replace deprecated strncpy() with strscpy()

Posted by Thorsten Blum 10 months ago

On 7. Apr 2025, at 22:30, Kees Cook wrote:
> On Mon, Apr 07, 2025 at 09:01:53PM +0200, Thorsten Blum wrote:
>> On 7. Apr 2025, at 20:28, Kees Cook wrote:
>>> On Wed, Feb 26, 2025 at 07:55:26PM +0100, Thorsten Blum wrote:
>>>> strncpy() is deprecated for NUL-terminated destination buffers; use
>>>> strscpy() instead.
>>>> 
>>>> Compile-tested only.
>>>> 
>>>> Link: https://github.com/KSPP/linux/issues/90
>>>> Cc: linux-hardening@vger.kernel.org
>>>> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
>>>> ---
>>> 
>>> Standard question for these kinds of conversions: Why is it safe that
>>> this is not NUL padded? I haven't found where this buffer is being
>>> zeroed out, but it probably is (given the "- 1" on the length), but
>>> without run-time testing, this needs much more careful analysis.
>> 
>> I think this was submitted before I started to explain this better.
>> 
>> 'wr_obj' is the zeroed out 'buf' returned from sli_config_cmd_init().
> 
> I don't see how dma->virt and buf are associated?

Since dma is NULL, sli_config_cmd_init() returns config->payload.embed
early (it doesn't get to return dma->virt) and before we have

    memset(buf, 0, SLI4_BMBX_SIZE);
    config = buf;

and SLI4_BMBX_SIZE is 256 which matches the size of sli4_cmd_sli_config.

It's not very obvious tbh.