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dahdi: Do not access invalid memory if invalid local span number is passed to spantype attribute.

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This fixes potential kernel panic due to accessing invalid memory if passing
invalid local span number to 'spantype' attribute via sysfs.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
(cherry picked from commit 860eb4ab48)
This commit is contained in:
Shaun Ruffell 2014-01-14 15:13:28 -06:00
parent c03330ae9d
commit d485a6ff21
1 changed files with 13 additions and 9 deletions
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22
drivers/dahdi/dahdi-sysfs.c
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@ -629,7 +629,8 @@ dahdi_spantype_store(struct device *dev, struct device_attribute *attr,
{ {
struct dahdi_device *const ddev = to_ddev(dev); struct dahdi_device *const ddev = to_ddev(dev);
int ret; int ret;
struct dahdi_span *span; struct dahdi_span *span = NULL;
struct dahdi_span *cur;
unsigned int local_span_number; unsigned int local_span_number;
char spantype_name[80]; char spantype_name[80];
enum spantypes spantype; enum spantypes spantype;
@ -645,9 +646,18 @@ dahdi_spantype_store(struct device *dev, struct device_attribute *attr,
return -EINVAL; return -EINVAL;
} }
list_for_each_entry(span, &ddev->spans, device_node) { list_for_each_entry(cur, &ddev->spans, device_node) {
if (local_spanno(span) == local_span_number) if (local_spanno(cur) == local_span_number) {
span = cur;
break; break;
}
}
if (!span || (local_spanno(span) != local_span_number)) {
module_printk(KERN_WARNING,
"%d is not a valid local span number "
"for this device.\n", local_span_number);
return -EINVAL;
} }
if (test_bit(DAHDI_FLAGBIT_REGISTERED, &span->flags)) { if (test_bit(DAHDI_FLAGBIT_REGISTERED, &span->flags)) {
@ -656,12 +666,6 @@ dahdi_spantype_store(struct device *dev, struct device_attribute *attr,
return -EINVAL; return -EINVAL;
} }
if (local_spanno(span) != local_span_number) {
module_printk(KERN_WARNING,
"%d is not a valid local span number "
"for this device.\n", local_span_number);
return -EINVAL;
}
if (!span->ops->set_spantype) { if (!span->ops->set_spantype) {
module_printk(KERN_WARNING, "Span %s does not support " module_printk(KERN_WARNING, "Span %s does not support "