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* [PATCH v2] resource: Fix integer overflow at reallocation
@ 2018-04-08  7:20 Takashi Iwai
  2018-04-10  0:23 ` Andrew Morton
  0 siblings, 1 reply; 7+ messages in thread
From: Takashi Iwai @ 2018-04-08  7:20 UTC (permalink / raw)
  To: Andrew Morton; +Cc: Ram Pai, Bjorn Helgaas, Michael Henders, linux-kernel

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.

Fixes: 23c570a67448 ("resource: ability to resize an allocated resource")
Reported-and-tested-by: Michael Henders <>
Reviewed-by: Ram Pai <>
Cc: <>
Signed-off-by: Takashi Iwai <>

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;

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2018-04-11 14:09 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-08  7:20 [PATCH v2] resource: Fix integer overflow at reallocation Takashi Iwai
2018-04-10  0:23 ` Andrew Morton
2018-04-10  4:54   ` Takashi Iwai
2018-04-10 20:42     ` Andrew Morton
2018-04-11  0:37       ` Ram Pai
2018-04-11  6:16         ` Takashi Iwai
2018-04-11 14:08           ` Ram Pai

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