CVE-2022-49193

In the Linux kernel, the following vulnerability has been resolved:

ice: fix 'scheduling while atomic' on aux critical err interrupt

There's a kernel BUG splat on processing aux critical error interrupts in ice_misc_intr():

[ 2100.917085] BUG: scheduling while atomic: swapper/15/0/0x00010000 ... [ 2101.060770] Call Trace: [ 2101.063229] <IRQ> [ 2101.065252] dump_stack+0x41/0x60 [ 2101.068587] __schedule_bug.cold.100+0x4c/0x58 [ 2101.073060] __schedule+0x6a4/0x830 [ 2101.076570] schedule+0x35/0xa0 [ 2101.079727] schedule_preempt_disabled+0xa/0x10 [ 2101.084284] __mutex_lock.isra.7+0x310/0x420 [ 2101.088580] ? ice_misc_intr+0x201/0x2e0 [ice] [ 2101.093078] ice_send_event_to_aux+0x25/0x70 [ice] [ 2101.097921] ice_misc_intr+0x220/0x2e0 [ice] [ 2101.102232] __handle_irq_event_percpu+0x40/0x180 [ 2101.106965] handle_irq_event_percpu+0x30/0x80 [ 2101.111434] handle_irq_event+0x36/0x53 [ 2101.115292] handle_edge_irq+0x82/0x190 [ 2101.119148] handle_irq+0x1c/0x30 [ 2101.122480] do_IRQ+0x49/0xd0 [ 2101.125465] common_interrupt+0xf/0xf [ 2101.129146] </IRQ> ...

As Andrew correctly mentioned previously[0], the following call ladder happens:

ice_misc_intr() <- hardirq ice_send_event_to_aux() device_lock() mutex_lock() might_sleep() might_resched() <- oops

Add a new PF state bit which indicates that an aux critical error occurred and serve it in ice_service_task() in process context. The new ice_pf::oicr_err_reg is read-write in both hardirq and process contexts, but only 3 bits of non-critical data probably aren't worth explicit synchronizing (and they're even in the same byte [31:24]).

[0] https://lore.kernel.org/all/YeSRUVmrdmlUXHDn@lunn.ch