On Wed, May 16, 2018 at 12:15:36AM +0100, Ben Hutchings wrote:
On Wed, 2018-04-11 at 20:35 +0200, Greg Kroah-Hartman wrote:
4.4-stable review patch. If anyone has any objections, please let me know.
From: Will Deacon will.deacon@arm.com
[ Upstream commit 5f16a046f8e144c294ef98cd29d9458b5f8273e5 ]
FUTEX_OP_OPARG_SHIFT instructs the futex code to treat the 12-bit oparg field as a shift value, potentially leading to a left shift value that is negative or with an absolute value that is significantly larger then the size of the type. UBSAN chokes with:
[...]
Whilst I think this catches all of the issues, I'd much prefer to remove this stuff, as I think it's unused and the bugs are copy-pasted between a bunch of architectures.
[...]
Indeed. That more complete fix was done upstream by:
commit 30d6e0a4190d37740e9447e4e4815f06992dd8c3 Author: Jiri Slaby jslaby@suse.cz Date: Thu Aug 24 09:31:05 2017 +0200
futex: Remove duplicated code and fix undefined behaviour
It's a bit big for stable - though most of the changes are deletions. What do you think?
I think it makes a lot of sense, I've done the backport now, thanks.
greg k-h