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component: fix crash on x86_64 with hda audio drivers 

Maarten reports that the addition of releasing match data to the
component helper results in a general protection fault on x86_64.

This is caused by the devm resources being freed in reverse order
to their allocation, which caused a use-after-free of the match
array.

Switch the match array to be a more conventional kmalloc/kfree()
affair, explicitly freeing it along with the parent match data
structure.

Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: ce657b1cdd ("component: add support for releasing match data")
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2016-01-26 14:49:22 +00:00
parent ce657b1cdd
commit 9a4e7849b5
1 changed files with 4 additions and 2 deletions
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6
drivers/base/component.c
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@ -206,6 +206,8 @@ static void component_match_release(struct device *master,
if (mc->release)
mc->release(master, mc->data);
}
kfree(match->compare);
}
static void devm_component_match_release(struct device *dev, void *res)
@ -221,14 +223,14 @@ static int component_match_realloc(struct device *dev,
if (match->alloc == num)
return 0;
new = devm_kmalloc_array(dev, num, sizeof(*new), GFP_KERNEL);
new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
if (!new)
return -ENOMEM;
if (match->compare) {
memcpy(new, match->compare, sizeof(*new) *
min(match->num, num));
devm_kfree(dev, match->compare);
kfree(match->compare);
}
match->compare = new;
match->alloc = num;