Date:   Tue, 12 Apr 2022 10:40:03 +0300
From:   Dmitry Monakhov <dmtrmonakhov@...dex-team.ru>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, mingo@...hat.com,
        Dmitry Monakhov <dmtrmonakhov@...dex-team.ru>
Subject: [PATCH 1/2] x86/unwind/orc: recheck address range after stack info was updated

get_stack_info() detects stack type only by begin address, so we must
check that address range in question is fully covered by detected stack

Otherwise following crash is possible:
-> unwind_next_frame
   case ORC_TYPE_REGS:
     if (!deref_stack_regs(state, sp, &state->ip, &state->sp))
     -> deref_stack_regs
       -> stack_access_ok  <- here addr is inside stack range, but addr+len-1 is not, but we still exit with success
     *ip = READ_ONCE_NOCHECK(regs->ip); <- Here we hit stack guard fault
OOPS LOG:
<0>[ 1941.845743] BUG: stack guard page was hit at 000000000dd984a2 (stack is 00000000d1caafca..00000000613712f0)
<4>[ 1941.845744] kernel stack overflow (page fault): 0000 [#1] SMP NOPTI
<4>[ 1941.845744] CPU: 93 PID: 23787 Comm: context_switch1 Not tainted 5.4.145 #1
<4>[ 1941.845745] Hardware name: XXXXXXXXXXXXXX
<4>[ 1941.845746] RIP: 0010:unwind_next_frame+0x311/0x5b0
<4>[ 1941.845746] Code: 01 0f 84 f6 01 00 00 0f 83 cc fe ff ff e9 f9 fe ff ff ba a8 00 00 00 4c 89 fe 48 89 df e8 57 fa ff ff 84 c0 0f 84 d9 00 00 00 <49> 8b 87 80 00 00 00 48 89 43 48 49 8b 87 98 00 00 00 4c 89 7b 50
<4>[ 1941.845747] RSP: 0018:fffffe00012908f0 EFLAGS: 00010002
<4>[ 1941.845748] RAX: 0000000000000001 RBX: fffffe0001290930 RCX: 0000000000000001
<4>[ 1941.845748] RDX: 0000000000000002 RSI: ffff893d94719e80 RDI: ffffc9001b9d7fc8
<4>[ 1941.845748] RBP: 0000000000000004 R08: ffffffff81a009bf R09: ffffffff824c7c20
<4>[ 1941.845749] R10: ffffffff824c7c1c R11: 0000000000000023 R12: ffffffff826c9cde
<4>[ 1941.845749] R13: ffffffff81a009d2 R14: fffffe0001289ff0 R15: ffffc9001b9d7fc8
<4>[ 1941.845749] FS:  00007f57ff9aa700(0000) GS:ffff893f6f140000(0000) knlGS:0000000000000000
<4>[ 1941.845750] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[ 1941.845750] CR2: ffffc9001b9d8048 CR3: 000000bcd3936000 CR4: 0000000000340ee0
<4>[ 1941.845750] Call Trace:
<4>[ 1941.845750]  <NMI>
<4>[ 1941.845751]  perf_callchain_kernel+0x12b/0x140
<4>[ 1941.845751]  ? interrupt_entry+0xb2/0xc0
<4>[ 1941.845751]  get_perf_callchain+0x10d/0x280
<4>[ 1941.845751]  perf_callchain+0x6e/0x80
<4>[ 1941.845752]  perf_prepare_sample+0x87/0x540
<4>[ 1941.845752]  perf_event_output_forward+0x31/0x90
<4>[ 1941.845752]  ? sched_clock+0x5/0x10
<4>[ 1941.845752]  ? sched_clock_cpu+0xc/0xb0
<4>[ 1941.845753]  ? arch_perf_update_userpage+0xd0/0xe0
<4>[ 1941.845753]  ? sched_clock+0x5/0x10
<4>[ 1941.845753]  ? sched_clock_cpu+0xc/0xb0
<4>[ 1941.845753]  __perf_event_overflow+0x5a/0xf0
<4>[ 1941.845754]  perf_ibs_handle_irq+0x340/0x5b0
<4>[ 1941.845754]  ? interrupt_entry+0xb2/0xc0
<4>[ 1941.845754]  ? interrupt_entry+0xb2/0xc0
<4>[ 1941.845754]  ? __set_pte_vaddr+0x28/0x40
<4>[ 1941.845755]  ? __set_pte_vaddr+0x28/0x40
<4>[ 1941.845755]  ? set_pte_vaddr+0x3c/0x60
<4>[ 1941.845755]  ? __native_set_fixmap+0x24/0x30
<4>[ 1941.845755]  ? native_set_fixmap+0x3c/0xb0
<4>[ 1941.845756]  ? ghes_copy_tofrom_phys+0x98/0x130
<4>[ 1941.845756]  ? interrupt_entry+0xb2/0xc0
<4>[ 1941.845756]  ? __ghes_peek_estatus.isra.16+0x49/0xb0
<4>[ 1941.845756]  ? perf_ibs_nmi_handler+0x34/0x60
<4>[ 1941.845757]  ? sched_clock+0x5/0x10
<4>[ 1941.845757]  perf_ibs_nmi_handler+0x34/0x60
<4>[ 1941.845757]  nmi_handle+0x79/0x190
<4>[ 1941.845757]  default_do_nmi+0x3e/0x110
<4>[ 1941.845758]  do_nmi+0x18d/0x1e0
<4>[ 1941.845758]  end_repeat_nmi+0x16/0x50
<4>[ 1941.845758] RIP: 0010:syscall_return_via_sysret+0x26/0x7f
<4>[ 1941.845759] Code: 3e 09 00 00 41 5f 41 5e 41 5d 41 5c 5d 5b 5e 41 5a 41 59 41 58 58 5e 5a 5e 48 89 e7 65 48 8b 24 25 04 60 00 00 ff 77 28 ff 37 <50> eb 43 0f 20 df eb 34 48 89 f8 48 81 e7 ff 07 00 00 65 48 0f a3
<4>[ 1941.845759] RSP: 0018:fffffe0001289ff0 EFLAGS: 00000046
<4>[ 1941.845760] RAX: 0000000000000001 RBX: 0000559a21ff71d0 RCX: 00007f57ff286260
<4>[ 1941.845760] RDX: 0000000000000001 RSI: 00007ffe43dc3d17 RDI: ffffc9001b9d7fc8
<4>[ 1941.845760] RBP: 00007ffe43dc3d17 R08: 0000000000005ceb R09: 00007f57ff9aa700
<4>[ 1941.845761] R10: 00007f57ff9aa9d0 R11: 0000000000000246 R12: 00007f57ff9aa698
<4>[ 1941.845761] R13: 00007f57ff9b5d00 R14: 0000559a1d5bb070 R15: 0000000000000005
<4>[ 1941.845761]  ? syscall_return_via_sysret+0x26/0x7f
<4>[ 1941.845761]  ? syscall_return_via_sysret+0x26/0x7f
<4>[ 1941.845762]  </NMI>
<4>[ 1941.845762]  <ENTRY_TRAMPOLINE>
<4>[ 1941.845762]  </ENTRY_TRAMPOLINE>
<4>[ 1941.845762] Modules linked in: unix_diag ip6table_filter sch_fq_codel tcp_diag inet_diag act_police act_gact cls_u32 sch_ingress netconsole configfs 8021q garp stp mrp llc amd64_edac_mod edac_mce_amd ghash_clmulni_intel ipmi_ssif ipmi_si ipmi_devintf ipmi_msghandler sp5100_tco i2c_piix4 k10temp tcp_htcp tcp_bbr kvm_amd ccp kvm irqbypass mpls_gso mpls_iptunnel mpls_router fou6 fou ip_tunnel ip6_udp_tunnel udp_tunnel mlx4_en mlx4_core dummy msr ip6_tables ip_tables x_tables ip6_tunnel tunnel6 nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear ast drm_vram_helper i2c_algo_bit mlx5_core drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops mlxfw ttm pci_hyperv_intf tls drm

Signed-off-by: Dmitry Monakhov <dmtrmonakhov@...dex-team.ru>
---
 arch/x86/kernel/unwind_orc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 794fdef2501a..80b878772b86 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -343,7 +343,9 @@ static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
 	    (get_stack_info(addr, state->task, info, &state->stack_mask)))
 		return false;
 
-	return true;
+	/* Recheck range after stack info was updated */
+	return on_stack(info, addr, len);
+
 }
 
 static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,
-- 
2.7.4

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