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* [PATCH] drivers/bluetooth: Remove all strcpy() uses
@ 2021-07-18 15:36 Len Baker
  2021-07-18 16:12 ` Adam Sampson
  0 siblings, 1 reply; 3+ messages in thread
From: Len Baker @ 2021-07-18 15:36 UTC (permalink / raw)
  To: Kees Cook, Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz
  Cc: Len Baker, linux-bluetooth, linux-kernel, linux-hardening

strcpy() performs no bounds checking on the destination buffer. This
could result in linear overflows beyond the end of the buffer, leading
to all kinds of misbehaviors. The safe replacement is strscpy() but in
this case it is better to use the scnprintf to simplify the arithmetic.

This is a previous step in the path to remove the strcpy() function
entirely from the kernel.

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/bluetooth/btmrvl_sdio.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/bluetooth/btmrvl_sdio.c b/drivers/bluetooth/btmrvl_sdio.c
index cddd350beba3..d6674b367e05 100644
--- a/drivers/bluetooth/btmrvl_sdio.c
+++ b/drivers/bluetooth/btmrvl_sdio.c
@@ -1350,6 +1350,7 @@ static void btmrvl_sdio_coredump(struct device *dev)
 	u8 *dbg_ptr, *end_ptr, *fw_dump_data, *fw_dump_ptr;
 	u8 dump_num = 0, idx, i, read_reg, doneflag = 0;
 	u32 memory_size, fw_dump_len = 0;
+	int size = 0;

 	card = sdio_get_drvdata(func);
 	priv = card->priv;
@@ -1493,20 +1494,18 @@ static void btmrvl_sdio_coredump(struct device *dev)
 		struct memory_type_mapping *entry = &mem_type_mapping_tbl[idx];

 		if (entry->mem_ptr) {
-			strcpy(fw_dump_ptr, "========Start dump ");
-			fw_dump_ptr += strlen("========Start dump ");
-
-			strcpy(fw_dump_ptr, entry->mem_name);
-			fw_dump_ptr += strlen(entry->mem_name);
-
-			strcpy(fw_dump_ptr, "========\n");
-			fw_dump_ptr += strlen("========\n");
-
-			memcpy(fw_dump_ptr, entry->mem_ptr, entry->mem_size);
-			fw_dump_ptr += entry->mem_size;
-
-			strcpy(fw_dump_ptr, "\n========End dump========\n");
-			fw_dump_ptr += strlen("\n========End dump========\n");
+			size += scnprintf(fw_dump_ptr + size,
+					  sizeof(fw_dump_ptr) - size,
+					  "========Start dump %s========\n",
+					  entry->mem_name);
+
+			memcpy(fw_dump_ptr + size, entry->mem_ptr,
+			       entry->mem_size);
+			size += entry->mem_size;
+
+			size += scnprintf(fw_dump_ptr + size,
+					  sizeof(fw_dump_ptr) - size,
+					  "\n========End dump========\n");

 			vfree(mem_type_mapping_tbl[idx].mem_ptr);
 			mem_type_mapping_tbl[idx].mem_ptr = NULL;
--
2.25.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] drivers/bluetooth: Remove all strcpy() uses
  2021-07-18 15:36 [PATCH] drivers/bluetooth: Remove all strcpy() uses Len Baker
@ 2021-07-18 16:12 ` Adam Sampson
  2021-07-24 12:22   ` Len Baker
  0 siblings, 1 reply; 3+ messages in thread
From: Adam Sampson @ 2021-07-18 16:12 UTC (permalink / raw)
  To: Len Baker
  Cc: Kees Cook, Marcel Holtmann, Johan Hedberg,
	Luiz Augusto von Dentz, linux-bluetooth, linux-kernel,
	linux-hardening

Len Baker <len.baker@gmx.com> writes:

> strcpy() performs no bounds checking on the destination buffer. This
> could result in linear overflows beyond the end of the buffer, leading
> to all kinds of misbehaviors. The safe replacement is strscpy() but in
> this case it is better to use the scnprintf to simplify the arithmetic.
>
> This is a previous step in the path to remove the strcpy() function
> entirely from the kernel.
>
> Signed-off-by: Len Baker <len.baker@gmx.com>
> ---
>  drivers/bluetooth/btmrvl_sdio.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/bluetooth/btmrvl_sdio.c b/drivers/bluetooth/btmrvl_sdio.c
> index cddd350beba3..d6674b367e05 100644
> --- a/drivers/bluetooth/btmrvl_sdio.c
> +++ b/drivers/bluetooth/btmrvl_sdio.c
> @@ -1350,6 +1350,7 @@ static void btmrvl_sdio_coredump(struct device *dev)
>  	u8 *dbg_ptr, *end_ptr, *fw_dump_data, *fw_dump_ptr;
[...]
> +			size += scnprintf(fw_dump_ptr + size,
> +					  sizeof(fw_dump_ptr) - size,
[...]
> +			size += scnprintf(fw_dump_ptr + size,
> +					  sizeof(fw_dump_ptr) - size,

sizeof(fw_dump_ptr) there looks wrong -- you want the size of the buffer
it points to (fw_dump_len + 1)?

Thanks,

-- 
Adam Sampson <ats@offog.org>                         <http://offog.org/>

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] drivers/bluetooth: Remove all strcpy() uses
  2021-07-18 16:12 ` Adam Sampson
@ 2021-07-24 12:22   ` Len Baker
  0 siblings, 0 replies; 3+ messages in thread
From: Len Baker @ 2021-07-24 12:22 UTC (permalink / raw)
  To: Adam Sampson
  Cc: Len Baker, Kees Cook, Marcel Holtmann, Johan Hedberg,
	Luiz Augusto von Dentz, linux-bluetooth, linux-kernel,
	linux-hardening

Hi,

On Sun, Jul 18, 2021 at 05:12:55PM +0100, Adam Sampson wrote:
> Len Baker <len.baker@gmx.com> writes:
>
> > strcpy() performs no bounds checking on the destination buffer. This
> > could result in linear overflows beyond the end of the buffer, leading
> > to all kinds of misbehaviors. The safe replacement is strscpy() but in
> > this case it is better to use the scnprintf to simplify the arithmetic.
> >
> > This is a previous step in the path to remove the strcpy() function
> > entirely from the kernel.
> >
> > Signed-off-by: Len Baker <len.baker@gmx.com>
> > ---
> >  drivers/bluetooth/btmrvl_sdio.c | 27 +++++++++++++--------------
> >  1 file changed, 13 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/bluetooth/btmrvl_sdio.c b/drivers/bluetooth/btmrvl_sdio.c
> > index cddd350beba3..d6674b367e05 100644
> > --- a/drivers/bluetooth/btmrvl_sdio.c
> > +++ b/drivers/bluetooth/btmrvl_sdio.c
> > @@ -1350,6 +1350,7 @@ static void btmrvl_sdio_coredump(struct device *dev)
> >  	u8 *dbg_ptr, *end_ptr, *fw_dump_data, *fw_dump_ptr;
> [...]
> > +			size += scnprintf(fw_dump_ptr + size,
> > +					  sizeof(fw_dump_ptr) - size,
> [...]
> > +			size += scnprintf(fw_dump_ptr + size,
> > +					  sizeof(fw_dump_ptr) - size,
>
> sizeof(fw_dump_ptr) there looks wrong -- you want the size of the buffer
> it points to (fw_dump_len + 1)?

Apologies. I will work on it and I will send a new version for review.
Thanks for the feedback.

>
> Thanks,
>
> --
> Adam Sampson <ats@offog.org>                         <http://offog.org/>

Regards,
Len

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-07-24 12:22 UTC | newest]

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2021-07-18 15:36 [PATCH] drivers/bluetooth: Remove all strcpy() uses Len Baker
2021-07-18 16:12 ` Adam Sampson
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