This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed- trusty' to 'verification-done-trusty'. If the problem still exists, change the tag 'verification-needed-trusty' to 'verification-failed- trusty'.
If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: verification-needed-trusty -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1755817 Title: Segmentation fault in ldt_gdt_64 Status in linux package in Ubuntu: Incomplete Status in linux source package in Trusty: Fix Committed Bug description: == SRU Justification == The ldt_gdt_64 x86 selftest segfaults with the currently released Trusty 3.13 kernel. The commit that introduced the segfault is aeb315d60afe ("x86/ldt: Make modify_ldt synchronous"). == Fix == Upstream commit 8ff5bd2e1e27 ("x86/signal/64: Fix SS if needed when delivering a 64-bit signal"). This commit was found by doing a reverse git bisect of the upstream kernel (i.e., when did the test stop segfaulting). The backport of the commit is a simple context adjustment. The second commit is a pre-requisite which simply renames some defines (no functional changes). == Regression Potential == Low. The commit is very small and isolated and the code path is only executed in special circumstances (and for x86 only). I built a test kernel and ran the whole set of x86 selftests and perf NMI test for several hours to verify stability. == Test Case == Run the ldt_gdt_64 x86 selftets from a current upstream kernel source. The test segfaults consistently. Original bug description: 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]> To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1755817/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
