[PATCH] drivers/soc: Remove all strcpy() uses in favor of strscpy()

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().

Signed-off-by: Len Baker <redacted>
---
This is a task of the KSPP [1]

[1] https://github.com/KSPP/linux/issues/88

 drivers/soc/qcom/pdr_interface.c    | 13 +++++++------
 drivers/soc/renesas/r8a779a0-sysc.c |  6 ++++--
 drivers/soc/renesas/rcar-sysc.c     |  6 ++++--
 drivers/soc/ti/knav_dma.c           |  2 +-
 4 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/soc/qcom/pdr_interface.c b/drivers/soc/qcom/pdr_interface.c
index 915d5bc3d46e..cf119fde749d 100644
--- a/drivers/soc/qcom/pdr_interface.c
+++ b/drivers/soc/qcom/pdr_interface.c

@@ -131,7 +131,7 @@ static int pdr_register_listener(struct pdr_handle *pdr,
 		return ret;

 	req.enable = enable;
-	strcpy(req.service_path, pds->service_path);
+	strscpy(req.service_path, pds->service_path, sizeof(req.service_path));

 	ret = qmi_send_request(&pdr->notifier_hdl, &pds->addr,
 			       &txn, SERVREG_REGISTER_LISTENER_REQ,

@@ -257,7 +257,7 @@ static int pdr_send_indack_msg(struct pdr_handle *pdr, struct pdr_service *pds,
 		return ret;

 	req.transaction_id = tid;
-	strcpy(req.service_path, pds->service_path);
+	strscpy(req.service_path, pds->service_path, sizeof(req.service_path));

 	ret = qmi_send_request(&pdr->notifier_hdl, &pds->addr,
 			       &txn, SERVREG_SET_ACK_REQ,

@@ -406,7 +406,7 @@ static int pdr_locate_service(struct pdr_handle *pdr, struct pdr_service *pds)
 		return -ENOMEM;

 	/* Prepare req message */
-	strcpy(req.service_name, pds->service_name);
+	strscpy(req.service_name, pds->service_name, sizeof(req.service_name));
 	req.domain_offset_valid = true;
 	req.domain_offset = 0;

@@ -531,8 +531,8 @@ struct pdr_service *pdr_add_lookup(struct pdr_handle *pdr,
 		return ERR_PTR(-ENOMEM);

 	pds->service = SERVREG_NOTIFIER_SERVICE;
-	strcpy(pds->service_name, service_name);
-	strcpy(pds->service_path, service_path);
+	strscpy(pds->service_name, service_name, sizeof(pds->service_name));
+	strscpy(pds->service_path, service_path, sizeof(pds->service_path));
 	pds->need_locator_lookup = true;

 	mutex_lock(&pdr->list_lock);

@@ -587,7 +587,8 @@ int pdr_restart_pd(struct pdr_handle *pdr, struct pdr_service *pds)
 			break;

 		/* Prepare req message */
-		strcpy(req.service_path, pds->service_path);
+		strscpy(req.service_path, pds->service_path,
+			sizeof(req.service_path));
 		addr = pds->addr;
 		break;
 	}

diff --git a/drivers/soc/renesas/r8a779a0-sysc.c b/drivers/soc/renesas/r8a779a0-sysc.c
index d464ffa1be33..25f8164b96d0 100644
--- a/drivers/soc/renesas/r8a779a0-sysc.c
+++ b/drivers/soc/renesas/r8a779a0-sysc.c

@@ -404,19 +404,21 @@ static int __init r8a779a0_sysc_pd_init(void)
 	for (i = 0; i < info->num_areas; i++) {
 		const struct r8a779a0_sysc_area *area = &info->areas[i];
 		struct r8a779a0_sysc_pd *pd;
+		size_t area_name_size;

 		if (!area->name) {
 			/* Skip NULLified area */
 			continue;
 		}

-		pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+		area_name_size = strlen(area->name) + 1;
+		pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
 		if (!pd) {
 			error = -ENOMEM;
 			goto out_put;
 		}

-		strcpy(pd->name, area->name);
+		strscpy(pd->name, area->name, area_name_size);
 		pd->genpd.name = pd->name;
 		pd->pdr = area->pdr;
 		pd->flags = area->flags;

diff --git a/drivers/soc/renesas/rcar-sysc.c b/drivers/soc/renesas/rcar-sysc.c
index 53387a72ca00..0eae5ce0eeb0 100644
--- a/drivers/soc/renesas/rcar-sysc.c
+++ b/drivers/soc/renesas/rcar-sysc.c

@@ -396,19 +396,21 @@ static int __init rcar_sysc_pd_init(void)
 	for (i = 0; i < info->num_areas; i++) {
 		const struct rcar_sysc_area *area = &info->areas[i];
 		struct rcar_sysc_pd *pd;
+		size_t area_name_size;

 		if (!area->name) {
 			/* Skip NULLified area */
 			continue;
 		}

-		pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+		area_name_size = strlen(area->name) + 1;
+		pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
 		if (!pd) {
 			error = -ENOMEM;
 			goto out_put;
 		}

-		strcpy(pd->name, area->name);
+		strscpy(pd->name, area->name, area_name_size);
 		pd->genpd.name = pd->name;
 		pd->ch.chan_offs = area->chan_offs;
 		pd->ch.chan_bit = area->chan_bit;

diff --git a/drivers/soc/ti/knav_dma.c b/drivers/soc/ti/knav_dma.c
index 591d14ebcb11..5f9816d317a5 100644
--- a/drivers/soc/ti/knav_dma.c
+++ b/drivers/soc/ti/knav_dma.c

@@ -691,7 +691,7 @@ static int dma_init(struct device_node *cloud, struct device_node *dma_node)
 	dma->max_rx_flow = max_rx_flow;
 	dma->max_tx_chan = min(max_tx_chan, max_tx_sched);
 	atomic_set(&dma->ref_count, 0);
-	strcpy(dma->name, node->name);
+	strscpy(dma->name, node->name, sizeof(dma->name));
 	spin_lock_init(&dma->lock);

 	for (i = 0; i < dma->max_tx_chan; i++) {
--

2.25.1


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Hi Len,

On Sun, Jul 25, 2021 at 5:15 PM Len Baker [off-list ref] wrote:

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().

Signed-off-by: Len Baker <redacted>

Thanks for your patch!

---
This is a task of the KSPP [1]

[1] https://github.com/KSPP/linux/issues/88

Any chance the almost one year old question in that ticket can be
answered?

 drivers/soc/renesas/rcar-sysc.c     |  6 ++++--

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

But please see my comments below...

I wouldn't mind a shorter name, like "n".

Likewise.

                if (!area->name) {
                        /* Skip NULLified area */
                        continue;
                }

-               pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+               area_name_size = strlen(area->name) + 1;
+               pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
                if (!pd) {
                        error = -ENOMEM;
                        goto out_put;
                }

-               strcpy(pd->name, area->name);
+               strscpy(pd->name, area->name, area_name_size);
                pd->genpd.name = pd->name;
                pd->ch.chan_offs = area->chan_offs;
                pd->ch.chan_bit = area->chan_bit;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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From: Geert Uytterhoeven

Sent: 26 July 2021 09:03

Hi Len,

On Sun, Jul 25, 2021 at 5:15 PM Len Baker [off-list ref] wrote:

quoted

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().

Signed-off-by: Len Baker <redacted>

Thanks for your patch!

quoted

---
This is a task of the KSPP [1]

[1] https://github.com/KSPP/linux/issues/88

Any chance the almost one year old question in that ticket can be
answered?

quoted

 drivers/soc/renesas/rcar-sysc.c     |  6 ++++--

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

But please see my comments below...

quoted

--- a/drivers/soc/renesas/r8a779a0-sysc.c
+++ b/drivers/soc/renesas/r8a779a0-sysc.c

@@ -404,19 +404,21 @@ static int __init r8a779a0_sysc_pd_init(void)
        for (i = 0; i < info->num_areas; i++) {
                const struct r8a779a0_sysc_area *area = &info->areas[i];
                struct r8a779a0_sysc_pd *pd;
+               size_t area_name_size;

I wouldn't mind a shorter name, like "n".

quoted

                if (!area->name) {
                        /* Skip NULLified area */
                        continue;
                }

-               pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+               area_name_size = strlen(area->name) + 1;
+               pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
                if (!pd) {
                        error = -ENOMEM;
                        goto out_put;
                }

-               strcpy(pd->name, area->name);
+               strscpy(pd->name, area->name, area_name_size);

You can just use memcpy().

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
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On 2021-07-28 09:36, David Laight wrote:

From: Geert Uytterhoeven

quoted

Sent: 26 July 2021 09:03

Hi Len,

On Sun, Jul 25, 2021 at 5:15 PM Len Baker [off-list ref] wrote:

quoted

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().

Signed-off-by: Len Baker <redacted>

Thanks for your patch!

quoted

---
This is a task of the KSPP [1]

[1] https://github.com/KSPP/linux/issues/88

Any chance the almost one year old question in that ticket can be
answered?

quoted

  drivers/soc/renesas/rcar-sysc.c     |  6 ++++--

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

But please see my comments below...

quoted

--- a/drivers/soc/renesas/r8a779a0-sysc.c
+++ b/drivers/soc/renesas/r8a779a0-sysc.c

@@ -404,19 +404,21 @@ static int __init r8a779a0_sysc_pd_init(void)
         for (i = 0; i < info->num_areas; i++) {
                 const struct r8a779a0_sysc_area *area = &info->areas[i];
                 struct r8a779a0_sysc_pd *pd;
+               size_t area_name_size;

I wouldn't mind a shorter name, like "n".

quoted

                 if (!area->name) {
                         /* Skip NULLified area */
                         continue;
                 }

-               pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+               area_name_size = strlen(area->name) + 1;
+               pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
                 if (!pd) {
                         error = -ENOMEM;
                         goto out_put;
                 }

-               strcpy(pd->name, area->name);
+               strscpy(pd->name, area->name, area_name_size);

You can just use memcpy().

Indeed. In fact I'd go as far as saying that it might be worth teaching 
static checkers to recognise patterns that boil down to strscpy(dst, 
src, strlen(src) + 1) and flag them as suspect, because AFAICS that 
would always represent either an unnecessarily elaborate memcpy(), or 
far worse just an obfuscated strcpy().

Robin.

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Hi,

On Mon, Jul 26, 2021 at 10:03:18AM +0200, Geert Uytterhoeven wrote:

Hi Len,

On Sun, Jul 25, 2021 at 5:15 PM Len Baker [off-list ref] wrote:

quoted

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().

Signed-off-by: Len Baker <redacted>

Thanks for your patch!

quoted

---
This is a task of the KSPP [1]

[1] https://github.com/KSPP/linux/issues/88

Any chance the almost one year old question in that ticket can be
answered?

I'm a kernel newbie and I have chosen this task as a starting point. So,
I think that someone with more experience could answer this question.

Kees: Any comments?

quoted

 drivers/soc/renesas/rcar-sysc.c     |  6 ++++--

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

But please see my comments below...

quoted

--- a/drivers/soc/renesas/r8a779a0-sysc.c
+++ b/drivers/soc/renesas/r8a779a0-sysc.c

@@ -404,19 +404,21 @@ static int __init r8a779a0_sysc_pd_init(void)
        for (i = 0; i < info->num_areas; i++) {
                const struct r8a779a0_sysc_area *area = &info->areas[i];
                struct r8a779a0_sysc_pd *pd;
+               size_t area_name_size;

I wouldn't mind a shorter name, like "n".

Ok, I will change this for the next version.

quoted

                if (!area->name) {
                        /* Skip NULLified area */
                        continue;
                }

-               pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+               area_name_size = strlen(area->name) + 1;
+               pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
                if (!pd) {
                        error = -ENOMEM;
                        goto out_put;
                }

-               strcpy(pd->name, area->name);
+               strscpy(pd->name, area->name, area_name_size);
                pd->genpd.name = pd->name;
                pd->pdr = area->pdr;
                pd->flags = area->flags;

diff --git a/drivers/soc/renesas/rcar-sysc.c b/drivers/soc/renesas/rcar-sysc.c
index 53387a72ca00..0eae5ce0eeb0 100644
--- a/drivers/soc/renesas/rcar-sysc.c
+++ b/drivers/soc/renesas/rcar-sysc.c

@@ -396,19 +396,21 @@ static int __init rcar_sysc_pd_init(void)
        for (i = 0; i < info->num_areas; i++) {
                const struct rcar_sysc_area *area = &info->areas[i];
                struct rcar_sysc_pd *pd;
+               size_t area_name_size;

Likewise.

Ok, understood.

Regards,
Len

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Hi,

On Wed, Jul 28, 2021 at 10:36:09AM +0100, Robin Murphy wrote:

On 2021-07-28 09:36, David Laight wrote:

quoted

quoted

quoted

-               strcpy(pd->name, area->name);
+               strscpy(pd->name, area->name, area_name_size);

You can just use memcpy().

Indeed. In fact I'd go as far as saying that it might be worth teaching
static checkers to recognise patterns that boil down to strscpy(dst, src,
strlen(src) + 1) and flag them as suspect, because AFAICS that would always
represent either an unnecessarily elaborate memcpy(), or far worse just an
obfuscated strcpy().

Ok, I will use the memcpy function instead of strscpy. Thanks for the
feedback.

Robin.

Regards,
Len

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