From: Takashi Iwai tiwai@suse.de Subject: resource: fix integer overflow at reallocation
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 PCI resource assigned after 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 of the newly calculated resource for avoiding the integer overflow problem.
Bugzilla: http://bugzilla.opensuse.org/show_bug.cgi?id=1086739 Link: http://lkml.kernel.org/r/s5hpo37d5l8.wl-tiwai@suse.de Fixes: 23c570a67448 ("resource: ability to resize an allocated resource") Signed-off-by: Takashi Iwai tiwai@suse.de Reported-by: Michael Henders hendersm@shaw.ca Tested-by: Michael Henders hendersm@shaw.ca Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Ram Pai linuxram@us.ibm.com Cc: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
kernel/resource.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN kernel/resource.c~resource-fix-integer-overflow-at-reallocation-v1 kernel/resource.c --- a/kernel/resource.c~resource-fix-integer-overflow-at-reallocation-v1 +++ a/kernel/resource.c @@ -651,7 +651,8 @@ static int __find_resource(struct resour alloc.start = constraint->alignf(constraint->alignf_data, &avail, size, constraint->align); alloc.end = alloc.start + size - 1; - if (resource_contains(&avail, &alloc)) { + if (alloc.start <= alloc.end && + resource_contains(&avail, &alloc)) { new->start = alloc.start; new->end = alloc.end; return 0; _