Thread (20 messages) flat view 20 messages, 12 authors, 2016-08-25

Re: CVE-2014-9900 fix is not upstream

From: Joe Perches <joe@perches.com>
Date: 2016-08-23 20:36:35
Also in: lkml

On Tue, 2016-08-23 at 21:09 +0100, Al Viro wrote:
On Tue, Aug 23, 2016 at 11:24:06AM -0700, David Miller wrote:
quoted
quoted
On some versions and architectures.  Can you guarantee that you will
notice when an exception appears?
Again, show me the assembler output exhibiting the lack of
initialization, for this specific structure and situation.

That's all that I'm asking.
... and then we can file a bug report against the sodding compiler.  Note
that
struct ethtool_wolinfo {
        __u32   cmd;
        __u32   supported;
        __u32   wolopts;
        __u8    sopass[SOPASS_MAX];	// 6, actually
};
is not going to *have* padding.  Not on anything even remotely sane.
If array of 6 char as member of a struct requires 64bit alignment on some
architecture, I would really like some of what the designers of that ABI
must have been smoking.
try this on x86-64

$ pahole -C ethtool_wolinfo vmlinux
struct ethtool_wolinfo {
	__u32                      cmd;                  /*     0     4 */
	__u32                      supported;            /*     4     4 */
	__u32                      wolopts;              /*     8     4 */
	__u8                       sopass[6];            /*    12     6 */

	/* size: 20, cachelines: 1, members: 4 */
	/* padding: 2 */
	/* last cacheline: 20 bytes */
};
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