lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 16 Jan 2017 14:50:48 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Dmitry Vyukov' <>,
        Neil Horman <>
CC:     Vladislav Yasevich <>,
        David Miller <>,
        "" <>,
        netdev <>,
        LKML <>,
        Kees Cook <>,
        syzkaller <>
Subject: RE: sctp: kernel memory overwrite attempt detected in

From: Dmitry Vyukov
> Sent: 16 January 2017 14:04
> >> >> I've enabled CONFIG_HARDENED_USERCOPY_PAGESPAN on syzkaller fuzzer and
> >> The code also takes into account compound pages. As far as I
> >> understand the intention of the check is to effectively find
> >> out-of-bounds copies (e.g. goes beyond the current heap allocation). I
> >> would expect that stacks are allocated as compound pages and don't
> >> trigger this check. I don't see it is firing in other similar places.
> >>
> > Honestly, I'm not overly familiar with stack page allocation, at least not so
> > far as compound vs. single page allocation is concerned.  I suppose the question
> > your really asking here is: Have you found a case in which the syscall fuzzer
> > has forced the allocation of an insecure non-compound page on the stack, or is
> > this a false positive warning.  I can't provide the answer to that.
> Yes. I added Kees, author of CONFIG_HARDENED_USERCOPY_PAGESPAN, to To line.
> Kees, is this a false positive?

I'd guess that the kernel stack is (somehow) allocated page by page
rather than by a single multi-page allocate.
Or maybe vmalloc() isn't setting the required flag??


Powered by blists - more mailing lists