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Date: Mon, 20 Jul 2020 14:10:23 +0200
From: Mikhail Morfikov <mmorfikov@...il.com>
To: lkrg-users@...ts.openwall.com
Subject: Re: kernel: BUG: unable to handle page fault for
address: ffffffffab42fee7
On 20/07/2020 13.20, Solar Designer wrote:
>
> Oh, I think I understand now. LKRG checks its known UMH program
> pathnames at its initialization time and then only allows those that
> were actually found on the system. Since you don't have
> /sbin/bridge-stp, LKRG doesn't allow it. Then it also fails on trying
> to block its execution because of CPA.
>
> As a temporary workaround, you can try creating /sbin/bridge-stp as a
> copy of /bin/false.
It looks like this doesn't help much:
# cp /bin/false /sbin/bridge-stp
# ls -al /sbin/bridge-stp
-rwxr-xr-x 1 root root 35584 2020-07-20 14:02:00 /sbin/bridge-stp*
# sysctl -a | grep umh
lkrg.umh_enforce = 1
lkrg.umh_validate = 1
Jul 20 14:03:05 morfikownia kernel: [p_lkrg] Changing "umh_validate" logic. From Old[0] | Disable protection] to new[1] | Allow specific paths] one.
Jul 20 14:03:29 morfikownia kernel: virbr0: port 1(virbr0-nic) entered blocking state
Jul 20 14:03:29 morfikownia kernel: virbr0: port 1(virbr0-nic) entered disabled state
Jul 20 14:03:29 morfikownia kernel: device virbr0-nic entered promiscuous mode
Jul 20 14:03:29 morfikownia kernel: [p_lkrg] Blocked usermodehelper execution of [/sbin/bridge-stp]
Jul 20 14:03:29 morfikownia kernel: CPA protect Rodata RO: 0xffffffffb202f000 - 0xffffffffb202ffff PFN a7a2f req 8000000000000063 prevent 0000000000000002
Jul 20 14:03:29 morfikownia kernel: CPA protect Rodata RO: 0xffff92bd27a2f000 - 0xffff92bd27a2ffff PFN a7a2f req 8000000000000063 prevent 0000000000000002
Jul 20 14:03:29 morfikownia kernel: BUG: unable to handle page fault for address: ffffffffb202fee7
Jul 20 14:03:29 morfikownia kernel: #PF: supervisor write access in kernel mode
Jul 20 14:03:29 morfikownia kernel: #PF: error_code(0x0003) - permissions violation
Jul 20 14:03:29 morfikownia kernel: PGD a7c0c067 P4D a7c0c067 PUD a7c0d063 PMD 20d877063 PTE 80000000a7a2f061
Jul 20 14:03:29 morfikownia kernel: Oops: 0003 [#1] PREEMPT SMP PTI
Jul 20 14:03:29 morfikownia kernel: CPU: 2 PID: 152515 Comm: kworker/u16:3 Tainted: G O T 5.7.9-amd64 #18
Jul 20 14:03:29 morfikownia kernel: Hardware name: LENOVO 2349BM5/2349BM5, BIOS G1ETC2WW (2.82 ) 08/07/2019
Jul 20 14:03:29 morfikownia kernel: RIP: 0010:memset_erms+0x9/0x10
Jul 20 14:03:29 morfikownia kernel: Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
Jul 20 14:03:29 morfikownia kernel: RSP: 0000:ffffb60503d23c48 EFLAGS: 00010202
Jul 20 14:03:29 morfikownia kernel: RAX: 000000000000002f RBX: ffffffffb202f000 RCX: 0000000000000010
Jul 20 14:03:29 morfikownia kernel: RDX: 0000000000000010 RSI: 000000000000002f RDI: ffffffffb202fee7
Jul 20 14:03:29 morfikownia kernel: RBP: ffffffffb202fee7 R08: 00000000000004d1 R09: ffffffffb202fee7
Jul 20 14:03:29 morfikownia kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff92be4e9e8380
Jul 20 14:03:29 morfikownia kernel: R13: ffffddf248361de8 R14: ffffffffc026ed00 R15: 0000000000000000
Jul 20 14:03:29 morfikownia kernel: FS: 0000000000000000(0000) GS:ffff92be96280000(0000) knlGS:0000000000000000
Jul 20 14:03:29 morfikownia kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 20 14:03:29 morfikownia kernel: CR2: ffffffffb202fee7 CR3: 00000001d64e2006 CR4: 00000000001606e0
Jul 20 14:03:29 morfikownia kernel: Call Trace:
Jul 20 14:03:29 morfikownia kernel: p_call_usermodehelper_entry+0x352/0x390 [p_lkrg]
Jul 20 14:03:29 morfikownia kernel: pre_handler_kretprobe+0xaf/0x1b0
Jul 20 14:03:29 morfikownia kernel: ? call_usermodehelper_exec_work+0x160/0x160
Jul 20 14:03:29 morfikownia kernel: ? call_usermodehelper_exec_async+0x5/0x1a0
Jul 20 14:03:29 morfikownia kernel: kprobe_ftrace_handler+0xb8/0x120
Jul 20 14:03:29 morfikownia kernel: ? call_usermodehelper_exec_work+0x160/0x160
Jul 20 14:03:29 morfikownia kernel: ? ret_from_fork+0x35/0x40
Jul 20 14:03:29 morfikownia kernel: ftrace_ops_assist_func+0x8d/0xf0
Jul 20 14:03:29 morfikownia kernel: ? call_usermodehelper_exec_work+0x160/0x160
Jul 20 14:03:29 morfikownia kernel: 0xffffffffc019c0c8
Jul 20 14:03:29 morfikownia kernel: ? call_usermodehelper_exec_work+0x160/0x160
Jul 20 14:03:29 morfikownia kernel: ? call_usermodehelper_exec_async+0x1/0x1a0
Jul 20 14:03:29 morfikownia kernel: call_usermodehelper_exec_async+0x5/0x1a0
Jul 20 14:03:29 morfikownia kernel: ret_from_fork+0x35/0x40
Jul 20 14:03:29 morfikownia kernel: Modules linked in: p_lkrg(O)
Jul 20 14:03:29 morfikownia kernel: CR2: ffffffffb202fee7
Jul 20 14:03:29 morfikownia kernel: ---[] end trace 3955a69aad25e9dd ]---
Jul 20 14:03:29 morfikownia kernel: RIP: 0010:memset_erms+0x9/0x10
Jul 20 14:03:29 morfikownia kernel: Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
Jul 20 14:03:29 morfikownia kernel: RSP: 0000:ffffb60503d23c48 EFLAGS: 00010202
Jul 20 14:03:29 morfikownia kernel: RAX: 000000000000002f RBX: ffffffffb202f000 RCX: 0000000000000010
Jul 20 14:03:29 morfikownia kernel: RDX: 0000000000000010 RSI: 000000000000002f RDI: ffffffffb202fee7
Jul 20 14:03:29 morfikownia kernel: RBP: ffffffffb202fee7 R08: 00000000000004d1 R09: ffffffffb202fee7
Jul 20 14:03:29 morfikownia kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff92be4e9e8380
Jul 20 14:03:29 morfikownia kernel: R13: ffffddf248361de8 R14: ffffffffc026ed00 R15: 0000000000000000
Jul 20 14:03:29 morfikownia kernel: FS: 0000000000000000(0000) GS:ffff92be96280000(0000) knlGS:0000000000000000
Jul 20 14:03:29 morfikownia kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 20 14:03:29 morfikownia kernel: CR2: ffffffffb202fee7 CR3: 00000001d64e2006 CR4: 00000000001606e0
Jul 20 14:03:29 morfikownia kernel: note: kworker/u16:3[152515] exited with preempt_count 2
Jul 20 14:03:29 morfikownia kernel: virbr0: failed to start userspace STP (9)
Jul 20 14:03:29 morfikownia kernel: virbr0: port 1(virbr0-nic) entered blocking state
Jul 20 14:03:29 morfikownia kernel: virbr0: port 1(virbr0-nic) entered listening state
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