From: Tyrel Datwyler <tyreld@xxxxxxxxxxxxx> commit aeaadcde1a60138bceb65de3cdaeec78170b4459 upstream. Currently the back pointer from a queue to the vhost adapter isn't set until after subcrq interrupt registration. The value is available when a queue is first allocated and can/should be also set for primary and async queues as well as subcrqs. This fixes a crash observed during kexec/kdump on Power 9 with legacy XICS interrupt controller where a pending subcrq interrupt from the previous kernel can be replayed immediately upon IRQ registration resulting in dereference of a garbage backpointer in ibmvfc_interrupt_scsi(). Kernel attempted to read user page (58) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on read at 0x00000058 Faulting instruction address: 0xc008000003216a08 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [c008000003216a08] ibmvfc_interrupt_scsi+0x40/0xb0 [ibmvfc] LR [c0000000082079e8] __handle_irq_event_percpu+0x98/0x270 Call Trace: [c000000047fa3d80] [c0000000123e6180] 0xc0000000123e6180 (unreliable) [c000000047fa3df0] [c0000000082079e8] __handle_irq_event_percpu+0x98/0x270 [c000000047fa3ea0] [c000000008207d18] handle_irq_event+0x98/0x188 [c000000047fa3ef0] [c00000000820f564] handle_fasteoi_irq+0xc4/0x310 [c000000047fa3f40] [c000000008205c60] generic_handle_irq+0x50/0x80 [c000000047fa3f60] [c000000008015c40] __do_irq+0x70/0x1a0 [c000000047fa3f90] [c000000008016d7c] __do_IRQ+0x9c/0x130 [c000000014622f60] [0000000020000000] 0x20000000 [c000000014622ff0] [c000000008016e50] do_IRQ+0x40/0xa0 [c000000014623020] [c000000008017044] replay_soft_interrupts+0x194/0x2f0 [c000000014623210] [c0000000080172a8] arch_local_irq_restore+0x108/0x170 [c000000014623240] [c000000008eb1008] _raw_spin_unlock_irqrestore+0x58/0xb0 [c000000014623270] [c00000000820b12c] __setup_irq+0x49c/0x9f0 [c000000014623310] [c00000000820b7c0] request_threaded_irq+0x140/0x230 [c000000014623380] [c008000003212a50] ibmvfc_register_scsi_channel+0x1e8/0x2f0 [ibmvfc] [c000000014623450] [c008000003213d1c] ibmvfc_init_sub_crqs+0xc4/0x1f0 [ibmvfc] [c0000000146234d0] [c0080000032145a8] ibmvfc_reset_crq+0x150/0x210 [ibmvfc] [c000000014623550] [c0080000032147c8] ibmvfc_init_crq+0x160/0x280 [ibmvfc] [c0000000146235f0] [c00800000321a9cc] ibmvfc_probe+0x2a4/0x530 [ibmvfc] Link: https://lore.kernel.org/r/20220616191126.1281259-2-tyreld@xxxxxxxxxxxxx Fixes: 3034ebe26389 ("scsi: ibmvfc: Add alloc/dealloc routines for SCSI Sub-CRQ Channels") Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Brian King <brking@xxxxxxxxxxxxxxxxxx> Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/scsi/ibmvscsi/ibmvfc.c | 3 ++- drivers/scsi/ibmvscsi/ibmvfc.h | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) --- a/drivers/scsi/ibmvscsi/ibmvfc.c +++ b/drivers/scsi/ibmvscsi/ibmvfc.c @@ -5682,6 +5682,8 @@ static int ibmvfc_alloc_queue(struct ibm queue->cur = 0; queue->fmt = fmt; queue->size = PAGE_SIZE / fmt_size; + + queue->vhost = vhost; return 0; } @@ -5790,7 +5792,6 @@ static int ibmvfc_register_scsi_channel( } scrq->hwq_id = index; - scrq->vhost = vhost; LEAVE; return 0; --- a/drivers/scsi/ibmvscsi/ibmvfc.h +++ b/drivers/scsi/ibmvscsi/ibmvfc.h @@ -789,6 +789,7 @@ struct ibmvfc_queue { spinlock_t _lock; spinlock_t *q_lock; + struct ibmvfc_host *vhost; struct ibmvfc_event_pool evt_pool; struct list_head sent; struct list_head free; @@ -797,7 +798,6 @@ struct ibmvfc_queue { union ibmvfc_iu cancel_rsp; /* Sub-CRQ fields */ - struct ibmvfc_host *vhost; unsigned long cookie; unsigned long vios_cookie; unsigned long hw_irq;
