i2c-designware: NULL ptr at RIP: 0010:regmap_read+0x12/0x70

[Borislav Petkov]

Hi,

we're seeing the below splat in our testing of linux-next.

Disassembling Code: gives

  17:	90                   	nop
  18:	f3 0f 1e fa          	endbr64
  1c:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  21:	55                   	push   %rbp
  22:	48 89 e5             	mov    %rsp,%rbp
  25:	41 55                	push   %r13
  27:	41 54                	push   %r12
  29:	53                   	push   %rbx
  2a:*	8b 87 fc 01 00 00    	mov    0x1fc(%rdi),%eax		<-- trapping instruction

which is

regmap_read:
	endbr64
1:	call	__fentry__
	.section __mcount_loc, "a",@progbits
	.quad 1b
	.previous
	pushq	%rbp	#
	movq	%rsp, %rbp	#,
	pushq	%r13	#
	pushq	%r12	#
	pushq	%rbx	#
# drivers/base/regmap/regmap.c:2826: 	if (!IS_ALIGNED(reg, map->reg_stride))
	movl	508(%rdi), %eax	# map_12(D)->reg_stride, tmp107
	^^^^^^^^

i.e., that @map argument is 0.

Looking at the call stack, I see

  2409205acd3c ("i2c: designware: fix __i2c_dw_disable() in case master is holding SCL low")

which does that dev->map deref in __i2c_dw_disable() but maybe ->map is
invalid by then...?

Just a stab in the dark anyway...

Thx.

[    6.245173] i2c_designware AMDI0010:00: Unknown Synopsys component type: 0xffffffff
[    6.252683] BUG: kernel NULL pointer dereference, address: 00000000000001fc
[    6.256551] #PF: supervisor read access in kernel mode
[    6.256551] #PF: error_code(0x0000) - not-present page
[    6.256551] PGD 0 
[    6.256551] Oops: 0000 [#1] PREEMPT SMP NOPTI
[    6.256551] CPU: 32 PID: 211 Comm: kworker/32:0 Not tainted 6.7.0-rc6-next-20231222-1703820640818 #1
[    6.256551] Workqueue: pm pm_runtime_work
[    6.256551] RIP: 0010:regmap_read+0x12/0x70
[    6.256551] Code: 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 <8b> 87 fc 01 00 00 83 e8 01 85 f0 75 42 48 89 fb 41 89 f4 49 89 d5
[    6.256551] RSP: 0018:ff7fa5c740bcbc98 EFLAGS: 00010246
[    6.256551] RAX: 0000000000000000 RBX: ff38ff5c159f1028 RCX: 0000000000000008
[    6.256551] RDX: ff7fa5c740bcbcc4 RSI: 0000000000000034 RDI: 0000000000000000
[    6.256551] RBP: ff7fa5c740bcbcb0 R08: ff38ff5c02ceb8b0 R09: ff38ff5c002a4500
[    6.256551] R10: 0000000000000003 R11: 0000000000000003 R12: ff38ff5c159f1028
[    6.256551] R13: 0000000000000000 R14: 0000000000000000 R15: ff38ff5c159ed8f4
[    6.256551] FS:  0000000000000000(0000) GS:ff38ff6b0d200000(0000) knlGS:0000000000000000
[    6.256551] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    6.256551] CR2: 00000000000001fc CR3: 000000007403c001 CR4: 0000000000771ef0
[    6.256551] PKRU: 55555554
[    6.256551] Call Trace:
[    6.256551]  <TASK>
[    6.256551]  ? show_regs+0x6d/0x80
[    6.256551]  ? __die+0x29/0x70
[    6.256551]  ? page_fault_oops+0x153/0x4a0
[    6.256551]  ? do_user_addr_fault+0x30f/0x6c0
[    6.256551]  ? exc_page_fault+0x7c/0x190
[    6.256551]  ? asm_exc_page_fault+0x2b/0x30
[    6.256551]  ? regmap_read+0x12/0x70
[    6.256551]  ? update_load_avg+0x82/0x7d0
[    6.256551]  __i2c_dw_disable+0x38/0x180
[    6.256551]  i2c_dw_disable+0x3f/0xb0
[    6.256551]  i2c_dw_runtime_suspend+0x33/0x50
[    6.256551]  ? __pfx_pm_generic_runtime_suspend+0x10/0x10
[    6.256551]  pm_generic_runtime_suspend+0x2f/0x40
[    6.256551]  __rpm_callback+0x48/0x120
[    6.256551]  ? __pfx_pm_generic_runtime_suspend+0x10/0x10
[    6.256551]  rpm_callback+0x66/0x70
[    6.256551]  ? __pfx_pm_generic_runtime_suspend+0x10/0x10
[    6.256551]  rpm_suspend+0x166/0x700
[    6.256551]  ? srso_alias_return_thunk+0x5/0xfbef5
[    6.256551]  ? __schedule+0x3df/0x1720
[    6.256551]  pm_runtime_work+0xb2/0xd0
[    6.256551]  process_one_work+0x178/0x350
[    6.256551]  worker_thread+0x2f5/0x420
[    6.256551]  ? __pfx_worker_thread+0x10/0x10
[    6.256551]  kthread+0xf5/0x130
[    6.256551]  ? __pfx_kthread+0x10/0x10
[    6.256551]  ret_from_fork+0x3d/0x60
[    6.256551]  ? __pfx_kthread+0x10/0x10
[    6.256551]  ret_from_fork_asm+0x1a/0x30
[    6.256551]  </TASK>
[    6.256551] Modules linked in:
[    6.256551] CR2: 00000000000001fc
[    6.256551] ---[ end trace 0000000000000000 ]---
[    6.256551] RIP: 0010:regmap_read+0x12/0x70
[    6.256551] Code: 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 <8b> 87 fc 01 00 00 83 e8 01 85 f0 75 42 48 89 fb 41 89 f4 49 89 d5
[    6.256551] RSP: 0018:ff7fa5c740bcbc98 EFLAGS: 00010246
[    6.256551] RAX: 0000000000000000 RBX: ff38ff5c159f1028 RCX: 0000000000000008
[    6.256551] RDX: ff7fa5c740bcbcc4 RSI: 0000000000000034 RDI: 0000000000000000
[    6.256551] RBP: ff7fa5c740bcbcb0 R08: ff38ff5c02ceb8b0 R09: ff38ff5c002a4500
[    6.256551] R10: 0000000000000003 R11: 0000000000000003 R12: ff38ff5c159f1028
[    6.256551] R13: 0000000000000000 R14: 0000000000000000 R15: ff38ff5c159ed8f4
[    6.256551] FS:  0000000000000000(0000) GS:ff38ff6b0d200000(0000) knlGS:0000000000000000
[    6.256551] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    6.256551] CR2: 00000000000001fc CR3: 000000007403c001 CR4: 0000000000771ef0
[    6.256551] PKRU: 55555554
[    6.256551] note: kworker/32:0[211] exited with irqs disabled


-- 
Regards/Gruss,
    Boris.

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