[PATCH] arm64/dma-mapping: Fix null-pointer check

Subsystems: arm64 port (aarch64 architecture), the rest

STALE3371d

7 messages, 3 authors, 2017-06-13 · open the first message on its own page

[PATCH] arm64/dma-mapping: Fix null-pointer check

From: Olav Haugan <hidden>
Date: 2017-06-10 19:41:28 

The current null-pointer check in __dma_alloc_coherent and
__dma_free_coherent is pretty much useless since we are dereferencing
the pointer before checking for null.
Check for null-pointer before the actual dereferencing of the pointer.

Signed-off-by: Olav Haugan <redacted>
---
 arch/arm64/mm/dma-mapping.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 3216e098c058..a4b65773711d 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -95,11 +95,6 @@ static void *__dma_alloc_coherent(struct device *dev, size_t size,
 				  dma_addr_t *dma_handle, gfp_t flags,
 				  unsigned long attrs)
 {
-	if (dev == NULL) {
-		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
-		return NULL;
-	}
-
 	if (IS_ENABLED(CONFIG_ZONE_DMA) &&
 	    dev->coherent_dma_mask <= DMA_BIT_MASK(32))
 		flags |= GFP_DMA;
@@ -128,10 +123,6 @@ static void __dma_free_coherent(struct device *dev, size_t size,
 	bool freed;
 	phys_addr_t paddr = dma_to_phys(dev, dma_handle);
 
-	if (dev == NULL) {
-		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
-		return;
-	}
 
 	freed = dma_release_from_contiguous(dev,
 					phys_to_page(paddr),
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
+		return NULL;
+	}
+
 	size = PAGE_ALIGN(size);
 
 	if (!coherent && !gfpflags_allow_blocking(flags)) {
@@ -192,8 +188,13 @@ static void __dma_free(struct device *dev, size_t size,
 		       void *vaddr, dma_addr_t dma_handle,
 		       unsigned long attrs)
 {
-	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
+	void *swiotlb_addr;
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA free\n");
+		return;
+	}
+	swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
 	size = PAGE_ALIGN(size);
 
 	if (!is_device_dma_coherent(dev)) {
-- 
2.13.0

Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Russell King - ARM Linux <linux@armlinux.org.uk>
Date: 2017-06-10 22:04:04 

On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
quoted hunk
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This re-introduces an instance that you say you're getting rid of...

 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
+		return NULL;
+	}
+
 	size = PAGE_ALIGN(size);
 
 	if (!coherent && !gfpflags_allow_blocking(flags)) {
-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2017-06-12 12:29:09 

On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
quoted hunk
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
+		return NULL;
+	}
+
 	size = PAGE_ALIGN(size);
 
 	if (!coherent && !gfpflags_allow_blocking(flags)) {
@@ -192,8 +188,13 @@ static void __dma_free(struct device *dev, size_t size,
 		       void *vaddr, dma_addr_t dma_handle,
 		       unsigned long attrs)
 {
-	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
+	void *swiotlb_addr;
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA free\n");
+		return;
+	}
+	swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
I don't think we need the checks anymore. With commit 1dccb598df54
("arm64: simplify dma_get_ops") __generic_dma_ops() returns
dummy_dma_ops when dev == NULL, so the above __dma_alloc/__dma_free
functions would not be called.

-- 
Catalin

Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Olav Haugan <hidden>
Date: 2017-06-12 20:33:32 

On 17-06-12 13:29:04, Catalin Marinas wrote:
On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
quoted
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
+		return NULL;
+	}
+
 	size = PAGE_ALIGN(size);
 
 	if (!coherent && !gfpflags_allow_blocking(flags)) {
@@ -192,8 +188,13 @@ static void __dma_free(struct device *dev, size_t size,
 		       void *vaddr, dma_addr_t dma_handle,
 		       unsigned long attrs)
 {
-	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
+	void *swiotlb_addr;
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA free\n");
+		return;
+	}
+	swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
I don't think we need the checks anymore. With commit 1dccb598df54
("arm64: simplify dma_get_ops") __generic_dma_ops() returns
dummy_dma_ops when dev == NULL, so the above __dma_alloc/__dma_free
functions would not be called.
Ah, you are right. I will remove the checks then! Thanks.

-- 
.Olav

The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Olav Haugan <hidden>
Date: 2017-06-12 20:36:22 

On 17-06-10 23:03:54, Russell King - ARM Linux wrote:
On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
quoted
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This re-introduces an instance that you say you're getting rid of...
The ARM64 version of is_device_dma_coherent() checks for !dev
already...But anyway I will completely remove the !dev checks in the
alloc/free functions since as Catalin pointed out it is coverted
elsewhere.

-- 
.Olav

The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Olav Haugan <hidden>
Date: 2017-06-12 20:50:33 

On 17-06-12 13:29:04, Catalin Marinas wrote:
On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
quoted
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
+		return NULL;
+	}
+
 	size = PAGE_ALIGN(size);
 
 	if (!coherent && !gfpflags_allow_blocking(flags)) {
@@ -192,8 +188,13 @@ static void __dma_free(struct device *dev, size_t size,
 		       void *vaddr, dma_addr_t dma_handle,
 		       unsigned long attrs)
 {
-	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
+	void *swiotlb_addr;
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA free\n");
+		return;
+	}
+	swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
I don't think we need the checks anymore. With commit 1dccb598df54
("arm64: simplify dma_get_ops") __generic_dma_ops() returns
dummy_dma_ops when dev == NULL, so the above __dma_alloc/__dma_free
functions would not be called.
We don't need the check in is_device_dma_coherent() either then right?

-- 
.Olav

The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2017-06-13 09:03:33 

On Mon, Jun 12, 2017 at 01:50:28PM -0700, Olav Haugan wrote:
On 17-06-12 13:29:04, Catalin Marinas wrote:
quoted
On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
quoted
@@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
 	bool coherent = is_device_dma_coherent(dev);
 	pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
+		return NULL;
+	}
+
 	size = PAGE_ALIGN(size);
 
 	if (!coherent && !gfpflags_allow_blocking(flags)) {
@@ -192,8 +188,13 @@ static void __dma_free(struct device *dev, size_t size,
 		       void *vaddr, dma_addr_t dma_handle,
 		       unsigned long attrs)
 {
-	void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
+	void *swiotlb_addr;
 
+	if (!dev) {
+		WARN_ONCE(1, "Use an actual device structure for DMA free\n");
+		return;
+	}
+	swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
I don't think we need the checks anymore. With commit 1dccb598df54
("arm64: simplify dma_get_ops") __generic_dma_ops() returns
dummy_dma_ops when dev == NULL, so the above __dma_alloc/__dma_free
functions would not be called.
We don't need the check in is_device_dma_coherent() either then right?
Right. The only user of this function outside
arch/arm64/mm/dma-mapping.c is Xen (shared with arm32 under
arch/arm/xen/) but since arm32 doesn't do this NULL check either, we
should be fine.

-- 
Catalin
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