Public bug reported: Trusty 3.13 segfaults when running ldt_gdt_64 from the kernel's x86 selftests.
git bisect revealed that the following commit introduced the issue: commit aeb315d60afee129d32558f4a4b356eec2e7da7b Author: Andy Lutomirski <[email protected]> Date: Thu Jul 30 14:31:32 2015 -0700 x86/ldt: Make modify_ldt synchronous CVE-2017-5754 commit 37868fe113ff2ba814b3b4eb12df214df555f8dc upstream. modify_ldt() has questionable locking and does not synchronize threads. Improve it: redesign the locking and synchronize all threads' LDTs using an IPI on all modifications. This will dramatically slow down modify_ldt in multithreaded programs, but there shouldn't be any multithreaded programs that care about modify_ldt's performance in the first place. This fixes some fallout from the CVE-2015-5157 fixes. Signed-off-by: Andy Lutomirski <[email protected]> Reviewed-by: Borislav Petkov <[email protected]> Cc: Andrew Cooper <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Jan Beulich <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sasha Levin <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/4c6978476782160600471bd865b318db34c7b628.1438291540.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> (cherry picked from commit 62fc7228f8cc8c89ecbd37008a0495ac28e41c5c) Signed-off-by: Juerg Haefliger <[email protected]> Signed-off-by: Stefan Bader <[email protected]> ** Affects: linux (Ubuntu) Importance: Undecided Status: Incomplete ** Affects: linux (Ubuntu Trusty) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1755817 Title: Segmentation fault in ldt_gdt_64 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1755817/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
