[PATCH 2/3] kexec: ensure user memory sizes do not wrap
Russell King - ARM Linux
linux at arm.linux.org.uk
Thu Apr 28 05:22:09 PDT 2016
On Thu, Apr 28, 2016 at 07:07:22PM +0800, Minfei Huang wrote:
> On 04/14/16 at 09:00pm, Russell King wrote:
> > Ensure that user memory sizes do not wrap around when validating the
> > user input, which can lead to the following input validation working
> > incorrectly.
> > Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> > ---
> > kernel/kexec_core.c | 2 ++
> > 1 file changed, 2 insertions(+)
> > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> > index 8d34308ea449..d719a4d0ef55 100644
> > --- a/kernel/kexec_core.c
> > +++ b/kernel/kexec_core.c
> > @@ -169,6 +169,8 @@ int sanity_check_segment_list(struct kimage *image)
> > mstart = image->segment[i].mem;
> > mend = mstart + image->segment[i].memsz;
> > + if (mstart > mend)
> > + return result;
> The type of image->segment[i].memsz is unsigned. So it is no need to
> have a test here.
Absolutely wrong. Consider the case:
segment[i].mem = 0xfff00000;
segment[i].size = 0x00200000;
Here, mstart will be 0xfff00000, and mend will be 0x00100000. Just
because it's some random type does not make things magically work.
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