UBUNTU: SAUCE: ACPICA: avoid accessing operands out-of-bounds

BugLink: https://bugs.launchpad.net/bugs/1942215

When the Timer operation is called, there are no arguments, and
acpi_ex_resolve_operands will be called with an out-of-bounds stack pointer
as num_operands is 0.

This does not usually cause any problems, as acpi_ex_resolve_operands will
ignore the parameter when the operation requires no arguments, as is the
case.

However, when the code is compiled with UBSAN, it will trigger, leading to
an oops with invalid opcode on Linux.

Fix it by using a NULL parameter when num_operands is 0.

[    8.285428] invalid opcode: 0000 [#1] SMP NOPTI
[    8.286436] CPU: 18 PID: 1522 Comm: systemd-udevd Not tainted 5.15.0-10-generic #10
[    8.287505] Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.0D.01.0395.022720191340 02/27/2019
[    8.288495] RIP: 0010:acpi_ds_exec_end_op+0x1be/0x7a6
[    8.289658] Code: 7b 0a 48 89 da 44 89 45 d4 48 98 48 8d 34 c3 e8 f8 3c 01 00 44 8b 45 d4 85 c0 41 89 c6 75 22 eb 9e 44 89 c0 41 80 f8 0b 76 02 <0f> 0b 48 8b 04 c5 c0 c0 ca aa 48 89 df ff d0 0f 1f 00 41 89 c4 eb
[    8.291858] RSP: 0018:ffffc38561a3f6d0 EFLAGS: 00010286
[    8.292888] RAX: 0000000000000000 RBX: ffffa0aa87c91800 RCX: 0000000000000040
[    8.294056] RDX: ffffffffffffffff RSI: ffffffffaacabf40 RDI: 00000000000002cb
[    8.295839] RBP: ffffc38561a3f700 R08: 0000000000000000 R09: ffffa0aa9f5a1000
[    8.296030] IPMI message handler: version 39.2
[    8.297554] R10: ffffa0aa89cdec00 R11: 0000000000000003 R12: 0000000000000000
[    8.297556] R13: ffffa0aa9f5a10a0 R14: 0000000000000000 R15: 0000000000000000
[    8.297558] FS:  00007f68ba26b8c0(0000) GS:ffffa0d60ca80000(0000) knlGS:0000000000000000
[    8.297560] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    8.297561] CR2: 00007fdbb3b9eec8 CR3: 00000001176ba001 CR4: 00000000007706e0
[    8.297563] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    8.297564] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    8.297565] PKRU: 55555554
[    8.297566] Call Trace:
[    8.297569]  acpi_ps_parse_loop+0x587/0x660
[    8.297574]  acpi_ps_parse_aml+0x1af/0x552
[    8.297578]  acpi_ps_execute_method+0x208/0x2ca
[    8.297580]  acpi_ns_evaluate+0x34e/0x4f0
[    8.297583]  acpi_evaluate_object+0x18e/0x3b4
[    8.297587]  acpi_evaluate_dsm+0xb3/0x120
[    8.297593]  ? acpi_evaluate_dsm+0xb3/0x120
[    8.297596]  nfit_intel_shutdown_status+0xed/0x1a0 [nfit]
[    8.297606]  acpi_nfit_add_dimm+0x3cb/0x660 [nfit]
[    8.297614]  acpi_nfit_register_dimms+0x141/0x460 [nfit]
[    8.297620]  acpi_nfit_init+0x54f/0x620 [nfit]
[    8.327895]  acpi_nfit_add+0x18c/0x1f0 [nfit]
[    8.329341]  acpi_device_probe+0x49/0x170
[    8.330815]  really_probe+0x209/0x410
[    8.330820]  __driver_probe_device+0x109/0x180
[    8.330823]  driver_probe_device+0x23/0x90
[    8.330825]  __driver_attach+0xac/0x1b0
[    8.330828]  ? __device_attach_driver+0xe0/0xe0
[    8.330831]  bus_for_each_dev+0x7c/0xc0
[    8.330834]  driver_attach+0x1e/0x20
[    8.330835]  bus_add_driver+0x135/0x1f0
[    8.330837]  driver_register+0x95/0xf0
[    8.330840]  acpi_bus_register_driver+0x39/0x50
[    8.344874]  nfit_init+0x168/0x1000 [nfit]
[    8.344882]  ? 0xffffffffc0735000
[    8.344885]  do_one_initcall+0x46/0x1d0
[    8.350927]  ? kmem_cache_alloc_trace+0x18c/0x2c0
[    8.350933]  do_init_module+0x62/0x290
[    8.350940]  load_module+0xaa3/0xb30
[    8.350944]  __do_sys_finit_module+0xbf/0x120
[    8.350948]  __x64_sys_finit_module+0x18/0x20
[    8.350951]  do_syscall_64+0x59/0xc0
[    8.350955]  ? exit_to_user_mode_prepare+0x37/0xb0
[    8.350959]  ? irqentry_exit_to_user_mode+0x9/0x20
[    8.350963]  ? irqentry_exit+0x19/0x30
[    8.350965]  ? exc_page_fault+0x89/0x160
[    8.350968]  ? asm_exc_page_fault+0x8/0x30
[    8.350971]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[    8.350975] RIP: 0033:0x7f68ba7fc94d
[    8.350978] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b3 64 0f 00 f7 d8 64 89 01 48
[    8.350980] RSP: 002b:00007ffc7e0b93c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[    8.350984] RAX: ffffffffffffffda RBX: 000055bbb29a4a00 RCX: 00007f68ba7fc94d
[    8.350985] RDX: 0000000000000000 RSI: 00007f68ba9923fe RDI: 0000000000000006
[    8.350987] RBP: 0000000000020000 R08: 0000000000000000 R09: 0000000000000000
[    8.350988] R10: 0000000000000006 R11: 0000000000000246 R12: 00007f68ba9923fe
[    8.350989] R13: 000055bbb28e3a20 R14: 000055bbb297d940 R15: 000055bbb297ea60

Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]>
Acked-by: Andrea Righi <[email protected]>
Signed-off-by: Paolo Pisati <[email protected]>

drivers/acpi/acpica/dswexec.c

@@ -397,11 +397,11 @@ acpi_status acpi_ds_exec_end_op(struct acpi_walk_state *walk_state)
 
 			/* Resolve all operands */
 
+			union acpi_operand_object **stack_ptr = NULL;
+			if (walk_state->num_operands > 0)
+				stack_ptr = ACPI_WALK_OPERANDS;
 			status = acpi_ex_resolve_operands(walk_state->opcode,
-							  &(walk_state->
-							    operands
-							    [walk_state->
-							     num_operands - 1]),
+							  stack_ptr,
 							  walk_state);
 		}