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resources: handle overflow when aligning start of available area 

If tmp.start is near ~0, ALIGN(tmp.start) may overflow, which would
make us think there's more available space than there really is.  We
would likely return something that conflicts with a previous resource,
which would cause a failure when allocate_resource() requests the newly-
allocated region.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=646027
Reported-by: Fabrice Bellet <fabrice@bellet.info>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Bjorn Helgaas 2010-10-26 15:41:28 -06:00 committed by Jesse Barnes
parent 6909ba14c2
commit a1862e3107
1 changed files with 13 additions and 8 deletions
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21
kernel/resource.c
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@ -392,7 +392,7 @@ static int find_resource(struct resource *root, struct resource *new,
void *alignf_data)
{
struct resource *this = root->child;
struct resource tmp = *new, alloc;
struct resource tmp = *new, avail, alloc;
tmp.start = root->start;
/*
@ -410,14 +410,19 @@ static int find_resource(struct resource *root, struct resource *new,
tmp.end = root->end;
resource_clip(&tmp, min, max);
tmp.start = ALIGN(tmp.start, align);
alloc.start = alignf(alignf_data, &tmp, size, align);
alloc.end = alloc.start + size - 1;
if (resource_contains(&tmp, &alloc)) {
new->start = alloc.start;
new->end = alloc.end;
return 0;
/* Check for overflow after ALIGN() */
avail = *new;
avail.start = ALIGN(tmp.start, align);
avail.end = tmp.end;
if (avail.start >= tmp.start) {
alloc.start = alignf(alignf_data, &avail, size, align);
alloc.end = alloc.start + size - 1;
if (resource_contains(&avail, &alloc)) {
new->start = alloc.start;
new->end = alloc.end;
return 0;
}
}
if (!this)
break;