We've got a bug report indicating a kernel panic at booting on an
x86-32 system, and it turned out to be the invalid resource assigned
after PCI resource reallocation.  __find_resource() first aligns the
resource start address and resets the end address with start+size-1
accordingly, then checks whether it's contained.  Here the end address
may overflow the integer, although resource_contains() still returns
true because the function validates only start and end address.  So
this ends up with returning an invalid resource (start > end).

There was already an attempt to cover such a problem in the commit
47ea91b4052d ("Resource: fix wrong resource window calculation"), but
this case is an overseen one.

This patch adds the validity check in resource_contains() to see
whether the given resource has a valid range for avoiding the integer
overflow problem.

Bugzilla: http://bugzilla.opensuse.org/show_bug.cgi?id=1086739
Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
Reported-and-tested-by: Michael Henders <hende...@shaw.ca>
Reviewed-by: Ram Pai <linux...@us.ibm.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Takashi Iwai <ti...@suse.de>

Andrew, could you pick this? It's still in a wild west...

v1->v2: check in resource_contains() instead of in __find_resource()

 include/linux/ioport.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index da0ebaec25f0..466d7be046eb 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -212,6 +212,9 @@ static inline bool resource_contains(struct resource *r1, 
struct resource *r2)
                return false;
        if (r1->flags & IORESOURCE_UNSET || r2->flags & IORESOURCE_UNSET)
                return false;
+       /* sanity check whether it's a valid resource range */
+       if (r2->end < r2->start)
+               return false;
        return r1->start <= r2->start && r1->end >= r2->end;

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