Re: [PATCH v10 00/26] Control-flow Enforcement: Shadow Stack

[Josh Poimboeuf <jpoimboe@redhat.com>]

On Thu, May 21, 2020 at 08:57:57AM -0700, Yu-cheng Yu wrote:
> On Thu, 2020-05-21 at 10:15 -0500, Josh Poimboeuf wrote:
> > On Wed, Apr 29, 2020 at 03:07:06PM -0700, Yu-cheng Yu wrote:
> > > Control-flow Enforcement (CET) is a new Intel processor feature that blocks
> > > return/jump-oriented programming attacks.  Details can be found in "Intel
> > > 64 and IA-32 Architectures Software Developer's Manual" [1].
> > > 
> > > This series depends on the XSAVES supervisor state series that was split
> > > out and submitted earlier [2].
> > > 
> > > I have gone through previous comments, and hope all concerns have been
> > > resolved now.  Please inform me if anything is overlooked.
> > > 
> > > Changes in v10:
> > 
> > Hi Yu-cheng,
> > 
> > Do you have a git branch with the latest Shadow Stack and IBT branches
> > applied?  I tried to apply IBT v9 on top of this, but I guess the SS
> > code has changed since then and it didn't apply cleanly.
> 
> It is here:
> 
> https://github.com/yyu168/linux_cet/commits/cet

Thanks.  FYI, I got the following warning on an AMD system.

[   18.936979] get of unsupported state
[   18.936989] WARNING: CPU: 251 PID: 1794 at arch/x86/kernel/fpu/xstate.c:919 get_xsave_addr+0x83/0x90
[   18.949676] Modules linked in:
[   18.952731] CPU: 251 PID: 1794 Comm: dracut-rootfs-g Not tainted 5.7.0-rc6+ #162
[   18.960121] Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, BIOS RDY1005C 11/22/2019
[   18.968198] RIP: 0010:get_xsave_addr+0x83/0x90
[   18.972637] Code: 5b c3 48 83 c4 08 31 c0 5b c3 80 3d f9 c2 7a 01 00 75 bc 48 c7 c7 c4 cb 8f a9 89 74 24 04 c6 05 e5 c2 7a 01 01 e8 3f 49 0a 00 <0f> 0b 8b 74 24 04 eb 9d 31 c0 c3 66 90 0f 1f 44 00 00 48 89 fe 0f
[   18.991373] RSP: 0018:ffffb8db103cfcd8 EFLAGS: 00010286
[   18.996591] RAX: 0000000000000000 RBX: ffff947da1189440 RCX: 0000000000000000
[   19.003715] RDX: 0000000000000000 RSI: ffffffffaa6809d8 RDI: ffffffffaa67e58c
[   19.010839] RBP: ffff947da1188000 R08: 0000000468bb5e6c R09: 0000000000000018
[   19.017962] R10: 0000000000000002 R11: 00000000000000f0 R12: ffffb8db103cfd20
[   19.025087] R13: ffff947da1189400 R14: 0000000000000000 R15: 0000000000000007
[   19.032211] FS:  00007f0a81b15740(0000) GS:ffff947dcf8c0000(0000) knlGS:0000000000000000
[   19.040321] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   19.046057] CR2: 00007f0a81b156c0 CR3: 0000003fa125a000 CR4: 0000000000340ee0
[   19.053183] Call Trace:
[   19.055637]  cet_restore_signal+0x26/0xf0
[   19.059649]  __fpu__restore_sig+0x4cc/0x6e0
[   19.063832]  ? remove_wait_queue+0x20/0x60
[   19.067928]  ? reuse_swap_page+0x6e/0x340
[   19.071939]  restore_sigcontext+0x162/0x1b0
[   19.076128]  ? recalc_sigpending+0x17/0x50
[   19.080223]  ? __set_task_blocked+0x34/0xa0
[   19.084401]  __do_sys_rt_sigreturn+0x92/0xde
[   19.088675]  do_syscall_64+0x55/0x1b0
[   19.092342]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   19.097394] RIP: 0033:0x7f0a811389d1
[   19.100970] Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 41 ba 08 00 00 00 b8 0e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 07 c3 66 0f 1f 44 00 00 48 8b 15 81 44 38 00
[   19.119709] RSP: 002b:00007ffd643d5dd8 EFLAGS: 00000246
[   19.124933] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f0a811389d1
[   19.132056] RDX: 0000000000000000 RSI: 00007ffd643d5e60 RDI: 0000000000000002
[   19.139182] RBP: 000055e140190e20 R08: 000055e14017a014 R09: 0000000000000001
[   19.146307] R10: 0000000000000008 R11: 0000000000000246 R12: 000055e13f47e4e0
[   19.153436] R13: 00007ffd643d5e60 R14: 0000000000000000 R15: 0000000000000000