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lib: logic_pio: Fix potential NULL pointer dereference

PATCH In review Gustavo A. R. Silva 3 participants 3 messages Apr 3, 2018 – Apr 4, 2018

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#0 lore raw

PATCH 1/1 lib: logic_pio: Fix potential NULL pointer dereference

new_range is being dereferenced before it is null checked, hence there is a potential null pointer dereference.

Fix this by moving the pointer dereference after new_range has been properly null checked.

Addresses-Coverity-ID: 1466163 ("Dereference before null check")

Fixes 0a7198426259 ("lib: Add generic PIO mapping method")
---
 lib/logic_pio.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
lib/logic_pio.c +5 -2
index 29cedea..30dfdce 100644
@@ -33,8 +33,8 @@ static DEFINE_MUTEX(io_range_mutex);
 int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 {
 	struct logic_pio_hwaddr *range;
-	resource_size_t start = new_range->hw_start;
-	resource_size_t end = new_range->hw_start + new_range->size;
+	resource_size_t start;
+	resource_size_t end;
 	resource_size_t mmio_sz = 0;
 	resource_size_t iio_sz = MMIO_UPPER_LIMIT;
 	int ret = 0;
@@ -42,6 +42,9 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	if (!new_range || !new_range->fwnode || !new_range->size)
 		return -EINVAL;
 
+	start = new_range->hw_start;
+	end = new_range->hw_start + new_range->size;
+
 	mutex_lock(&io_range_mutex);
 	list_for_each_entry_rcu(range, &io_range_list, list) {
 		if (range->fwnode == new_range->fwnode) {
Signature · 1 line
2.7.4
Reviewed-by on v1 1/1
#1 lore raw
Quoted 6 lines · Gustavo A. R. Silva

new_range is being dereferenced before it is null checked, hence there is a potential null pointer dereference.

Fix this by moving the pointer dereference after new_range has been properly null checked.

Hi Gustavo,

In fact we expect new_range to never be NULL. But, if we're going to check, then better make sure the check is correct...

Thanks,
John

Quoted 3 lines

Addresses-Coverity-ID: 1466163 ("Dereference before null check")

Fixes 0a7198426259 ("lib: Add generic PIO mapping method")
Quoted 30 lines
---
 lib/logic_pio.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
lib/logic_pio.c +5 -2
index 29cedea..30dfdce 100644
@@ -33,8 +33,8 @@ static DEFINE_MUTEX(io_range_mutex);
 int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 {
 	struct logic_pio_hwaddr *range;
-	resource_size_t start = new_range->hw_start;
-	resource_size_t end = new_range->hw_start + new_range->size;
+	resource_size_t start;
+	resource_size_t end;
 	resource_size_t mmio_sz = 0;
 	resource_size_t iio_sz = MMIO_UPPER_LIMIT;
 	int ret = 0;
@@ -42,6 +42,9 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	if (!new_range || !new_range->fwnode || !new_range->size)
 		return -EINVAL;
 
+	start = new_range->hw_start;
+	end = new_range->hw_start + new_range->size;
+
 	mutex_lock(&io_range_mutex);
 	list_for_each_entry_rcu(range, &io_range_list, list) {
 		if (range->fwnode == new_range->fwnode) {
#2 lore raw
In reply to Gustavo A. R. Silva

[+cc linux-pci]

Quoted 9 lines · Gustavo A. R. Silva

new_range is being dereferenced before it is null checked, hence there is a potential null pointer dereference.

Fix this by moving the pointer dereference after new_range has been properly null checked.

Addresses-Coverity-ID: 1466163 ("Dereference before null check")

Fixes 0a7198426259 ("lib: Add generic PIO mapping method")

Folded into 0a7198426259 on pci/lpc, thanks!

Quoted 32 lines
---
 lib/logic_pio.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
lib/logic_pio.c +5 -2
index 29cedea..30dfdce 100644
@@ -33,8 +33,8 @@ static DEFINE_MUTEX(io_range_mutex);
 int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 {
 	struct logic_pio_hwaddr *range;
-	resource_size_t start = new_range->hw_start;
-	resource_size_t end = new_range->hw_start + new_range->size;
+	resource_size_t start;
+	resource_size_t end;
 	resource_size_t mmio_sz = 0;
 	resource_size_t iio_sz = MMIO_UPPER_LIMIT;
 	int ret = 0;
@@ -42,6 +42,9 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	if (!new_range || !new_range->fwnode || !new_range->size)
 		return -EINVAL;
 
+	start = new_range->hw_start;
+	end = new_range->hw_start + new_range->size;
+
 	mutex_lock(&io_range_mutex);
 	list_for_each_entry_rcu(range, &io_range_list, list) {
 		if (range->fwnode == new_range->fwnode) {
Signature · 1 line
2.7.4