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. -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.
