CVE-2017-7482 Linux kernel: krb5 ticket decode len check.

[Wade Mealing <wmealing () redhat com>]

Gday,

David Howells has written a great description, so rather than reword what
he's written here is a quote directly from the git commit.

> From the patch notes:

---
    When a kerberos 5 ticket is being decoded so that it can be loaded into
an
    rxrpc-type key, there are several places in which the length of a
    variable-length field is checked to make sure that it's not going to
    overrun the available data - but the data is padded to the nearest
    four-byte boundary and the code doesn't check for this extra.  This
could
    lead to the size-remaining variable wrapping and the data pointer going
    over the end of the buffer.

    Fix this by making the various variable-length data checks use the
padded
    length.
---

> From what I can see, this could leak 3 bytes of memory to userspace or
possibly corrupt 3 bytes of memory,

Upstream fix
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5f2f97656ada8d811d3c1bef503ced266fcd53a0

Red Hat Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-7482

-- 

Wade Mealing

Product Security - Kernel, RHCE

Red Hat

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