Re: [PATCH 4.4 50/62] XEN uses irqdesc::irq_data_common::handler_data to store a per interrupt XEN data pointer which contains XEN specific information.

From: Stefan Bader
Date: Tue Sep 29 2020 - 09:13:32 EST

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On 01.09.20 17:10, Greg Kroah-Hartman wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> commit c330fb1ddc0a922f044989492b7fcca77ee1db46 upstream.
>
> handler data is meant for interrupt handlers and not for storing irq chip
> specific information as some devices require handler data to store internal
> per interrupt information, e.g. pinctrl/GPIO chained interrupt handlers.
>
> This obviously creates a conflict of interests and crashes the machine
> because the XEN pointer is overwritten by the driver pointer.

I cannot say whether this applies the same for the vanilla 4.4 stable kernels
but once this had been applied to our 4.4 based kernels, we observed Xen HVM
guests crashing on boot with:

[ 0.927538] ACPI: bus type PCI registered
[ 0.936008] acpiphp: ACPI Hot Plug PCI Controller Driver version: 0.5
[ 0.948739] PCI: Using configuration type 1 for base access
[ 0.960007] PCI: Using configuration type 1 for extended access
[ 0.984340] ACPI: Added _OSI(Module Device)
[ 0.988010] ACPI: Added _OSI(Processor Device)
[ 0.992007] ACPI: Added _OSI(3.0 _SCP Extensions)
[ 0.996013] ACPI: Added _OSI(Processor Aggregator Device)
[ 1.002103] BUG: unable to handle kernel paging request at ffffffffff5f3000
[ 1.004000] IP: [<ffffffff810592ff>] mp_irqdomain_activate+0x5f/0xa0
[ 1.004000] PGD 1e0f067 PUD 1e11067 PMD 1e12067 PTE 0
[ 1.004000] Oops: 0002 [#1] SMP
[ 1.004000] Modules linked in:
[ 1.004000] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 4.4.0-191-generic
#221-Ubuntu
[ 1.004000] Hardware name: Xen HVM domU, BIOS 4.6.5 04/18/2018
[ 1.004000] task: ffff880107db0000 ti: ffff880107dac000 task.ti: ffff880107dac000
[ 1.004000] RIP: 0010:[<ffffffff810592ff>] [<ffffffff810592ff>]
mp_irqdomain_activate+0x5f/0xa0
[ 1.004000] RSP: 0018:ffff880107dafc48 EFLAGS: 00010086
[ 1.004000] RAX: 0000000000000086 RBX: ffff8800eb852140 RCX: 0000000000000000
[ 1.004000] RDX: ffffffffff5f3000 RSI: 0000000000000001 RDI: 000000000020c000
[ 1.004000] RBP: ffff880107dafc50 R08: ffffffff81ebdfd0 R09: 00000000ffffffff
[ 1.004000] R10: 0000000000000011 R11: 0000000000000009 R12: ffff88010880d400
[ 1.004000] R13: 0000000000000001 R14: 0000000000000009 R15: ffff8800eb880080
[ 1.004000] FS: 0000000000000000(0000) GS:ffff880108ec0000(0000)
knlGS:0000000000000000
[ 1.004000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1.004000] CR2: ffffffffff5f3000 CR3: 0000000001e0a000 CR4: 00000000000006f0
[ 1.004000] Stack:
[ 1.004000] ffff88010880bc58 ffff880107dafc70 ffffffff810ea644 ffff88010880bc00
[ 1.004000] ffff88010880bc58 ffff880107dafca0 ffffffff810e6d88 ffffffff810e1009
[ 1.004000] ffff88010880bc00 ffff88010880bca0 ffff8800eb880080 ffff880107dafd38
[ 1.004000] Call Trace:
[ 1.004000] [<ffffffff810ea644>] irq_domain_activate_irq+0x44/0x50
[ 1.004000] [<ffffffff810e6d88>] irq_startup+0x38/0x90
[ 1.004000] [<ffffffff810e1009>] ? vprintk_default+0x29/0x40
[ 1.004000] [<ffffffff810e55e2>] __setup_irq+0x5a2/0x650
[ 1.004000] [<ffffffff811fc064>] ? kmem_cache_alloc_trace+0x1d4/0x1f0
[ 1.004000] [<ffffffff814a3870>] ? acpi_osi_handler+0xb0/0xb0
[ 1.004000] [<ffffffff810e582b>] request_threaded_irq+0xfb/0x1a0
[ 1.004000] [<ffffffff814a3870>] ? acpi_osi_handler+0xb0/0xb0
[ 1.004000] [<ffffffff814bf624>] ? acpi_ev_sci_dispatch+0x64/0x64
[ 1.004000] [<ffffffff814a3f0a>] acpi_os_install_interrupt_handler+0xaa/0x100
[ 1.004000] [<ffffffff81fb26e1>] ? acpi_sleep_proc_init+0x28/0x28
[ 1.004000] [<ffffffff814bf689>] acpi_ev_install_sci_handler+0x23/0x25
[ 1.004000] [<ffffffff814bcf03>] acpi_ev_install_xrupt_handlers+0x1c/0x6c
[ 1.004000] [<ffffffff81fb3e9d>] acpi_enable_subsystem+0x8f/0x93
[ 1.004000] [<ffffffff81fb276c>] acpi_init+0x8b/0x2c4
[ 1.004000] [<ffffffff8141ee1e>] ? kasprintf+0x4e/0x70
[ 1.004000] [<ffffffff81fb26e1>] ? acpi_sleep_proc_init+0x28/0x28
[ 1.004000] [<ffffffff810021f5>] do_one_initcall+0xb5/0x200
[ 1.004000] [<ffffffff810a6fda>] ? parse_args+0x29a/0x4a0
[ 1.004000] [<ffffffff81f69152>] kernel_init_freeable+0x177/0x218
[ 1.004000] [<ffffffff8185dcf0>] ? rest_init+0x80/0x80
[ 1.004000] [<ffffffff8185dcfe>] kernel_init+0xe/0xe0
[ 1.004000] [<ffffffff8186ae92>] ret_from_fork+0x42/0x80
[ 1.004000] [<ffffffff8185dcf0>] ? rest_init+0x80/0x80
[ 1.004000] Code: 8d 1c d2 8d ba 0b 02 00 00 44 8d 51 11 42 8b 14 dd 74 ec 10
82 c1 e7 0c 48 63 ff 81 e2 ff 0f 00 00 48 81 ea 00 10 80 00 48 29 fa <44> 89 12
89 72 10 42 8b 14 dd 74 ec 10 82 83 c1 10 81 e2 ff 0f
[ 1.004000] RIP [<ffffffff810592ff>] mp_irqdomain_activate+0x5f/0xa0
[ 1.004000] RSP <ffff880107dafc48>
[ 1.004000] CR2: ffffffffff5f3000
[ 1.004000] ---[ end trace 3201cae5b6bd7be1 ]---
[ 1.592027] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000009
[ 1.592027]

This is from a local server but same stack-trace happens on AWS instances while
initializing ACPI SCI. mp_irqdomain_activate is accessing chip_data expecting
ioapic data there. Oddly enough more recent kernels seem to do the same but not
crashing as HVM guest (neither seen for our 4.15 nor the 5.4).

Maybe someone could make sure the 4.4.y stable series is not also broken.

-Stefan
>
> As the XEN data is not handler specific it should be stored in
> irqdesc::irq_data::chip_data instead.
>
> A simple sed s/irq_[sg]et_handler_data/irq_[sg]et_chip_data/ cures that.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Roman Shaposhnik <roman@xxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Tested-by: Roman Shaposhnik <roman@xxxxxxxxxx>
> Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
> Link: https://lore.kernel.org/r/87lfi2yckt.fsf@xxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> ---
> drivers/xen/events/events_base.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -155,7 +155,7 @@ int get_evtchn_to_irq(unsigned evtchn)
> /* Get info for IRQ */
> struct irq_info *info_for_irq(unsigned irq)
> {
> - return irq_get_handler_data(irq);
> + return irq_get_chip_data(irq);
> }
>
> /* Constructors for packed IRQ information. */
> @@ -384,7 +384,7 @@ static void xen_irq_init(unsigned irq)
> info->type = IRQT_UNBOUND;
> info->refcnt = -1;
>
> - irq_set_handler_data(irq, info);
> + irq_set_chip_data(irq, info);
>
> list_add_tail(&info->list, &xen_irq_list_head);
> }
> @@ -433,14 +433,14 @@ static int __must_check xen_allocate_irq
>
> static void xen_free_irq(unsigned irq)
> {
> - struct irq_info *info = irq_get_handler_data(irq);
> + struct irq_info *info = irq_get_chip_data(irq);
>
> if (WARN_ON(!info))
> return;
>
> list_del(&info->list);
>
> - irq_set_handler_data(irq, NULL);
> + irq_set_chip_data(irq, NULL);
>
> WARN_ON(info->refcnt > 0);
>
> @@ -610,7 +610,7 @@ EXPORT_SYMBOL_GPL(xen_irq_from_gsi);
> static void __unbind_from_irq(unsigned int irq)
> {
> int evtchn = evtchn_from_irq(irq);
> - struct irq_info *info = irq_get_handler_data(irq);
> + struct irq_info *info = irq_get_chip_data(irq);
>
> if (info->refcnt > 0) {
> info->refcnt--;
> @@ -1114,7 +1114,7 @@ int bind_ipi_to_irqhandler(enum ipi_vect
>
> void unbind_from_irqhandler(unsigned int irq, void *dev_id)
> {
> - struct irq_info *info = irq_get_handler_data(irq);
> + struct irq_info *info = irq_get_chip_data(irq);
>
> if (WARN_ON(!info))
> return;
> @@ -1148,7 +1148,7 @@ int evtchn_make_refcounted(unsigned int
> if (irq == -1)
> return -ENOENT;
>
> - info = irq_get_handler_data(irq);
> + info = irq_get_chip_data(irq);
>
> if (!info)
> return -ENOENT;
> @@ -1176,7 +1176,7 @@ int evtchn_get(unsigned int evtchn)
> if (irq == -1)
> goto done;
>
> - info = irq_get_handler_data(irq);
> + info = irq_get_chip_data(irq);
>
> if (!info)
> goto done;
>
>

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