Olliver reported that his system crashes when plugging in Thunderbolt 1 device: BUG: kernel NULL pointer dereference, address: 0000000000000020 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:tb_port_do_update_credits+0x1b/0x130 [thunderbolt] Call Trace: <TASK> ? __die+0x23/0x70 ? page_fault_oops+0x171/0x4e0 ? exc_page_fault+0x7f/0x180 ? asm_exc_page_fault+0x26/0x30 ? tb_port_do_update_credits+0x1b/0x130 ? tb_switch_update_link_attributes+0x83/0xd0 tb_switch_add+0x7a2/0xfe0 tb_scan_port+0x236/0x6f0 tb_handle_hotplug+0x6db/0x900 process_one_work+0x171/0x340 worker_thread+0x27b/0x3a0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe5/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> This is due the fact that some Thunderbolt 1 devices only have one lane adapter. Fix this by checking for the lane 1 before we read its credits. Reported-by: Olliver Schinagl <oliver@xxxxxxxxxxx> Closes: https://lore.kernel.org/linux-usb/c24c7882-6254-4e68-8f22-f3e8f65dc84f@xxxxxxxxxxx/ Fixes: 81af2952e606 ("thunderbolt: Add support for asymmetric link") Cc: stable@xxxxxxxxxxxxxxx Cc: Gil Fine <gil.fine@xxxxxxxxxxxxxxx> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> --- Hi Olliver, I managed to reproduce this with a Thunderbolt 1 device. I wonder if you can try this patch and see if it fixes your issue too? drivers/thunderbolt/switch.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c index bca6f28c553b..72ebde0e34d7 100644 --- a/drivers/thunderbolt/switch.c +++ b/drivers/thunderbolt/switch.c @@ -1256,6 +1256,9 @@ int tb_port_update_credits(struct tb_port *port) ret = tb_port_do_update_credits(port); if (ret) return ret; + + if (!port->dual_link_port) + return 0; return tb_port_do_update_credits(port->dual_link_port); } -- 2.43.0
