CVE-2014-7843 Linux kernel: aarch64: copying from /dev/zero causes local DoS

[Petr Matousek <pmatouse () redhat com>]

It was found that a read of n*PAGE_SIZE+1 from /dev/zero
will cause the kernel to panic due to an unhandled exception since it's
not handling the single byte case with a fixup (anything larger than a
single byte will properly fault.)

A local, unprivileged user could use this flaw to crash the system.

Upstream patch proposal:
https://lkml.org/lkml/2014/11/12/584

References:
https://bugzilla.redhat.com/show_bug.cgi?id=1163744

-- 
Petr Matousek / Red Hat Product Security
PGP: 0xC44977CA 8107 AF16 A416 F9AF 18F3  D874 3E78 6F42 C449 77CA