Messages in this thread |  | | Date | Mon, 2 Apr 2018 12:09:03 -0700 | From | Ram Pai <> | Subject | Re: [PATCH] resource: Fix integer overflow at reallocation |
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On Mon, Apr 02, 2018 at 09:16:16AM +0200, Takashi Iwai wrote: > 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 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.
Should we move this check "alloc.start <= alloc.end" into resource_contains()? Doing so will catch all uses of such erroneous (overflowing) resources.
RP
> > Bugzilla: https://urldefense.proofpoint.com/v2/url?u=http-3A__bugzilla.opensuse.org_show-5Fbug.cgi-3Fid-3D1086739&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=m-UrKChQVkZtnPpjbF6YY99NbT8FBByQ-E-ygV8luxw&m=FoiwlR-LTJ9_EBQsLYSCqXuWrGhU1lXycdvhbaK7wOk&s=clxOtFUIAMlPNwQJZTaKnmIta9pMtJ8XprmwVd-ylvo&e= > Fixes: 23c570a67448 ("resource: ability to resize an allocated resource") > Reported-and-tested-by: Michael Henders <hendersm@shaw.ca> > Cc: <stable@vger.kernel.org> > Signed-off-by: Takashi Iwai <tiwai@suse.de> > --- > > Bjorn, I send this to you since the bug hits during PCI init, although > the culprit is in generic resource management. > > kernel/resource.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/resource.c b/kernel/resource.c > index e270b5048988..2af6c03858b9 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -651,7 +651,8 @@ static int __find_resource(struct resource *root, struct resource *old, > 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; > -- > 2.16.2
-- Ram Pai
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