avoid use of freed pointer

PATCH Superseded Gustavo A. R. Silva 3 participants 11 messages Feb 13, 2017 – Apr 5, 2017

Subsystems (2)

USB AMD geode CS5536 USB device controller driver

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Gustavo A. R. Silva

author

2017-02-13 15:38 UTC #0 lore raw

cover avoid use of freed pointer

Hello,

This patch series addesses Coverity ID 1091172, which reports the use of a freed pointer. udc_free_dma_chain() function was rewritten in order to fix this issue.

Unnecessary 'ret_val' variable was removed and the function prototype was modified.

Thanks

Gustavo A. R. Silva (2):
usb: gadget: udc: avoid use of freed pointer
usb: gadget: udc: remove unnecessary variable and update function
prototype

 drivers/usb/gadget/udc/amd5536udc.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

Signature · 1 line

2.5.0

Gustavo A. R. Silva

author

2017-02-13 16:07 UTC #1 lore raw

PATCH 1/2 usb: gadget: udc: avoid use of freed pointer

Rewrite udc_free_dma_chain() function to avoid use of pointer after free.

Addresses-Coverity-ID: 1091172

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/usb/gadget/udc/amd5536udc.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +11 -9

index ea03ca7..ded97a3 100644
@@ -611,21 +611,23 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
 	int ret_val = 0;
-	struct udc_data_dma	*td;
-	struct udc_data_dma	*td_last = NULL;
+	struct udc_data_dma *td = req->td_data;
 	unsigned int i;
 
+	dma_addr_t addr_aux = 0x00;
+	dma_addr_t addr = (dma_addr_t)td->next;
+	td->next = 0x00;
+
 	DBG(dev, "free chain req = %p\n", req);
 
 	/* do not free first desc., will be done by free for request */
-	td_last = req->td_data;
-	td = phys_to_virt(td_last->next);
-
 	for (i = 1; i < req->chain_len; i++) {
-		pci_pool_free(dev->data_requests, td,
-			      (dma_addr_t)td_last->next);
-		td_last = td;
-		td = phys_to_virt(td_last->next);
+		td = phys_to_virt(addr);
+		addr_aux = (dma_addr_t)td->next;
+		td->next = 0x00;
+		pci_pool_free(dev->data_requests, td, addr);
+		td = NULL;
+		addr = addr_aux;
 	}
 
 	return ret_val;

Signature · 1 line

2.5.0

Michal Nazarewicz

Acked-by on v1 1/2

2017-02-13 16:07 UTC #2 lore raw

Re: [PATCH 1/2] usb: gadget: udc: avoid use of freed pointer

Quoted 5 lines · Gustavo A. R. Silva

Rewrite udc_free_dma_chain() function to avoid use of pointer after free.
Addresses-Coverity-ID: 1091172
Reviewed-by Greg Kroah-Hartman <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>

Acked-by Michal Nazarewicz <[email protected]>

Quoted 9 lines

---
 drivers/usb/gadget/udc/amd5536udc.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +0 -0

index ea03ca7..ded97a3 100644

drivers/usb/gadget/udc/amd5536udc.c udc_alloc_request(struct usb_ep *usbep, gfp_t gfp) · line 617

Quoted 9 lines

drivers/usb/gadget/udc/amd5536udc.c +2 -2

@@ -611,21 +611,23 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
 	int ret_val = 0;
-	struct udc_data_dma	*td;
-	struct udc_data_dma	*td_last = NULL;
+	struct udc_data_dma *td = req->td_data;
 	unsigned int i;
 
+	dma_addr_t addr_aux = 0x00;

Perhaps call it ‘addr_next’ or ‘next’?

Quoted 7 lines

drivers/usb/gadget/udc/amd5536udc.c +3 -1

+	dma_addr_t addr = (dma_addr_t)td->next;
+	td->next = 0x00;
+
 	DBG(dev, "free chain req = %p\n", req);
 
 	/* do not free first desc., will be done by free for request */
-	td_last = req->td_data;

drivers/usb/gadget/udc/amd5536udc.c udc_alloc_request(struct usb_ep *usbep, gfp_t gfp) · line 627

Quoted 10 lines

drivers/usb/gadget/udc/amd5536udc.c +3 -6

-	td = phys_to_virt(td_last->next);
-
 	for (i = 1; i < req->chain_len; i++) {
-		pci_pool_free(dev->data_requests, td,
-			      (dma_addr_t)td_last->next);
-		td_last = td;
-		td = phys_to_virt(td_last->next);
+		td = phys_to_virt(addr);
+		addr_aux = (dma_addr_t)td->next;
+		td->next = 0x00;

This is unnecessary.

drivers/usb/gadget/udc/amd5536udc.c udc_alloc_request(struct usb_ep *usbep, gfp_t gfp) · line 629

Quoted 2 lines

drivers/usb/gadget/udc/amd5536udc.c +2 -0
+		pci_pool_free(dev->data_requests, td, addr);
+		td = NULL;

Ditto.

Quoted 7 lines

drivers/usb/gadget/udc/amd5536udc.c +1 -0
+		addr = addr_aux;
 	}
 
 	return ret_val;
Signature · 1 line
2.5.0

Signature · 3 lines

Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»

Gustavo A. R. Silva

author

2017-02-14 21:54 UTC #3 lore raw

Re: [PATCH 1/2] usb: gadget: udc: avoid use of freed pointer

Hi Michal,

Quoting Michal Nazarewicz <[email protected]>:

Quoted 55 lines · Gustavo A. R. Silva

Quoted 5 lines
Rewrite udc_free_dma_chain() function to avoid use of pointer after free.
Addresses-Coverity-ID: 1091172
Reviewed-by Greg Kroah-Hartman <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
Acked-by Michal Nazarewicz <[email protected]>
Quoted 9 lines
---
 drivers/usb/gadget/udc/amd5536udc.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)
drivers/usb/gadget/udc/amd5536udc.c +0 -0
index ea03ca7..ded97a3 100644
drivers/usb/gadget/udc/amd5536udc.c udc_alloc_request(struct usb_ep *usbep, gfp_t gfp) · line 617
Quoted 9 lines
drivers/usb/gadget/udc/amd5536udc.c +2 -2
@@ -611,21 +611,23 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
 	int ret_val = 0;
-	struct udc_data_dma	*td;
-	struct udc_data_dma	*td_last = NULL;
+	struct udc_data_dma *td = req->td_data;
 	unsigned int i;
 
+	dma_addr_t addr_aux = 0x00;
Perhaps call it ‘addr_next’ or ‘next’?
Quoted 7 lines
drivers/usb/gadget/udc/amd5536udc.c +3 -1
+	dma_addr_t addr = (dma_addr_t)td->next;
+	td->next = 0x00;
+
 	DBG(dev, "free chain req = %p\n", req);
 
 	/* do not free first desc., will be done by free for request */
-	td_last = req->td_data;
drivers/usb/gadget/udc/amd5536udc.c udc_alloc_request(struct usb_ep *usbep, gfp_t gfp) · line 627
Quoted 10 lines
drivers/usb/gadget/udc/amd5536udc.c +3 -6
-	td = phys_to_virt(td_last->next);
-
 	for (i = 1; i < req->chain_len; i++) {
-		pci_pool_free(dev->data_requests, td,
-			      (dma_addr_t)td_last->next);
-		td_last = td;
-		td = phys_to_virt(td_last->next);
+		td = phys_to_virt(addr);
+		addr_aux = (dma_addr_t)td->next;
+		td->next = 0x00;
This is unnecessary.
drivers/usb/gadget/udc/amd5536udc.c udc_alloc_request(struct usb_ep *usbep, gfp_t gfp) · line 629
Quoted 2 lines
drivers/usb/gadget/udc/amd5536udc.c +2 -0
+		pci_pool_free(dev->data_requests, td, addr);
+		td = NULL;
Ditto.

Quoted 8 lines

Quoted 7 lines
drivers/usb/gadget/udc/amd5536udc.c +1 -1
+		addr = addr_aux;
 	}
 
 	return ret_val;
--
2.5.0

Thanks for your comments, I will send version 2 shortly. --
Gustavo A. R. Silva

Gustavo A. R. Silva

author

2017-02-14 21:58 UTC #4 lore raw

PATCH v2 1/2 usb: gadget: udc: avoid use of freed pointer

Rewrite udc_free_dma_chain() function to avoid use of pointer after free.

Addresses-Coverity-ID: 1091172

Acked-by Michal Nazarewicz <[email protected]>

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
Changes in v2:
Remove 'td->next = 0x00' inside for loop. Remove unnecessary pointer nullification after free. Rename variable addr_aux to addr_next.

 drivers/usb/gadget/udc/amd5536udc.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +8 -9

index ea03ca7..821d088 100644
@@ -611,21 +611,20 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
 	int ret_val = 0;
-	struct udc_data_dma	*td;
-	struct udc_data_dma	*td_last = NULL;
+	struct udc_data_dma *td = req->td_data;
 	unsigned int i;
 
+	dma_addr_t addr_next = 0x00;
+	dma_addr_t addr = (dma_addr_t)td->next;
+
 	DBG(dev, "free chain req = %p\n", req);
 
 	/* do not free first desc., will be done by free for request */
-	td_last = req->td_data;
-	td = phys_to_virt(td_last->next);
-
 	for (i = 1; i < req->chain_len; i++) {
-		pci_pool_free(dev->data_requests, td,
-			      (dma_addr_t)td_last->next);
-		td_last = td;
-		td = phys_to_virt(td_last->next);
+		td = phys_to_virt(addr);
+		addr_next = (dma_addr_t)td->next;
+		pci_pool_free(dev->data_requests, td, addr);
+		addr = addr_next;
 	}
 
 	return ret_val;

Signature · 1 line

2.5.0

Gustavo A. R. Silva

author

2017-02-14 22:06 UTC #5 lore raw

PATCH v2 2/2 usb: gadget: udc: remove unnecessary variable and update function prototype

Remove unnecessary variable and update function prototype.

Acked-by Michal Nazarewicz <[email protected]>

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
Changes in v2:
None.

 drivers/usb/gadget/udc/amd5536udc.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +1 -4

index 821d088..67dd209 100644
@@ -608,9 +608,8 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 }
 
 /* frees pci pool descriptors of a DMA chain */
-static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
+static void udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
-	int ret_val = 0;
 	struct udc_data_dma *td = req->td_data;
 	unsigned int i;

@@ -626,8 +625,6 @@ static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 		pci_pool_free(dev->data_requests, td, addr);
 		addr = addr_next;
 	}
-
-	return ret_val;
 }
 
 /* Frees request packet, called by gadget driver */

Signature · 1 line

2.5.0

Gustavo A. R. Silva

author

2017-04-04 04:52 UTC #6 lore raw

PATCH v2 1/2 usb: gadget: udc: avoid use of freed pointer

In reply to Gustavo A. R. Silva

Rewrite udc_free_dma_chain() function to avoid use of pointer after free.

Addresses-Coverity-ID: 1091172

Acked-by Michal Nazarewicz <[email protected]>

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
Changes in v2:
Remove 'td->next = 0x00' inside for loop. Remove unnecessary pointer nullification after free. Rename variable addr_aux to addr_next.

 drivers/usb/gadget/udc/amd5536udc.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +8 -9

index ea03ca7..821d088 100644
@@ -611,21 +611,20 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
 	int ret_val = 0;
-	struct udc_data_dma	*td;
-	struct udc_data_dma	*td_last = NULL;
+	struct udc_data_dma *td = req->td_data;
 	unsigned int i;
 
+	dma_addr_t addr_next = 0x00;
+	dma_addr_t addr = (dma_addr_t)td->next;
+
 	DBG(dev, "free chain req = %p\n", req);
 
 	/* do not free first desc., will be done by free for request */
-	td_last = req->td_data;
-	td = phys_to_virt(td_last->next);
-
 	for (i = 1; i < req->chain_len; i++) {
-		pci_pool_free(dev->data_requests, td,
-			      (dma_addr_t)td_last->next);
-		td_last = td;
-		td = phys_to_virt(td_last->next);
+		td = phys_to_virt(addr);
+		addr_next = (dma_addr_t)td->next;
+		pci_pool_free(dev->data_requests, td, addr);
+		addr = addr_next;
 	}
 
 	return ret_val;

Signature · 1 line

2.5.0

Gustavo A. R. Silva

author

2017-04-04 04:34 UTC #7 lore raw

PATCH v2 2/2 usb: gadget: udc: remove unnecessary variable and update function prototype

Remove unnecessary variable and update function prototype.

Acked-by Michal Nazarewicz <[email protected]>

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
Changes in v2:
None.

 drivers/usb/gadget/udc/amd5536udc.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +1 -4

index 821d088..67dd209 100644
@@ -608,9 +608,8 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 }
 
 /* frees pci pool descriptors of a DMA chain */
-static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
+static void udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
-	int ret_val = 0;
 	struct udc_data_dma *td = req->td_data;
 	unsigned int i;

@@ -626,8 +625,6 @@ static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 		pci_pool_free(dev->data_requests, td, addr);
 		addr = addr_next;
 	}
-
-	return ret_val;
 }
 
 /* Frees request packet, called by gadget driver */

Signature · 1 line

2.5.0

Felipe Balbi

2017-04-05 12:33 UTC #8 lore raw

Re: [PATCH v2 1/2] usb: gadget: udc: avoid use of freed pointer

In reply to Gustavo A. R. Silva

Hi,

Quoted 6 lines · Gustavo A. R. Silva

Rewrite udc_free_dma_chain() function to avoid use of pointer after free.
Addresses-Coverity-ID: 1091172
Acked-by Michal Nazarewicz <[email protected]>
Reviewed-by Greg Kroah-Hartman <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>

doesn't apply to testing/next. Care to rebase?

Signature · 1 line

balbi

Gustavo A. R. Silva

author

2017-02-13 16:05 UTC #9 lore raw

PATCH 2/2 usb: gadget: udc: remove unnecessary variable and update function prototype

In reply to Gustavo A. R. Silva

Remove unnecessary variable and update function prototype.

Reviewed-by Greg Kroah-Hartman <[email protected]>

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/usb/gadget/udc/amd5536udc.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +1 -4

index ded97a3..3f64a06 100644
@@ -608,9 +608,8 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 }
 
 /* frees pci pool descriptors of a DMA chain */
-static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
+static void udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
-	int ret_val = 0;
 	struct udc_data_dma *td = req->td_data;
 	unsigned int i;

@@ -629,8 +628,6 @@ static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 		td = NULL;
 		addr = addr_aux;
 	}
-
-	return ret_val;
 }
 
 /* Frees request packet, called by gadget driver */

Signature · 1 line

2.5.0

Michal Nazarewicz

Acked-by on v1 2/2

2017-02-13 16:08 UTC #10 lore raw

Re: [PATCH 2/2] usb: gadget: udc: remove unnecessary variable and update function prototype

Quoted 4 lines · Gustavo A. R. Silva

Remove unnecessary variable and update function prototype.
Reviewed-by Greg Kroah-Hartman <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>

Acked-by Michal Nazarewicz <[email protected]>

Quoted 31 lines

---
 drivers/usb/gadget/udc/amd5536udc.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

drivers/usb/gadget/udc/amd5536udc.c +1 -4

index ded97a3..3f64a06 100644
@@ -608,9 +608,8 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 }
 
 /* frees pci pool descriptors of a DMA chain */
-static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
+static void udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
-	int ret_val = 0;
 	struct udc_data_dma *td = req->td_data;
 	unsigned int i;

@@ -629,8 +628,6 @@ static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 		td = NULL;
 		addr = addr_aux;
 	}
-
-	return ret_val;
 }
 
 /* Frees request packet, called by gadget driver */

Signature · 1 line

2.5.0

Signature · 3 lines

Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»