CVE-2023-53587

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

ring-buffer: Sync IRQ works before buffer destruction

If something was written to the buffer just before destruction, it may be possible (maybe not in a real system, but it did happen in ARCH=um with time-travel) to destroy the ringbuffer before the IRQ work ran, leading this KASAN report (or a crash without KASAN):

BUG: KASAN: slab-use-after-free in irq_work_run_list+0x11a/0x13a
Read of size 8 at addr 000000006d640a48 by task swapper/0

CPU: 0 PID: 0 Comm: swapper Tainted: G        W  O       6.3.0-rc1 #7
Stack:
 60c4f20f 0c203d48 41b58ab3 60f224fc
 600477fa 60f35687 60c4f20f 601273dd
 00000008 6101eb00 6101eab0 615be548
Call Trace:
 [<60047a58>] show_stack+0x25e/0x282
 [<60c609e0>] dump_stack_lvl+0x96/0xfd
 [<60c50d4c>] print_report+0x1a7/0x5a8
 [<603078d3>] kasan_report+0xc1/0xe9
 [<60308950>] __asan_report_load8_noabort+0x1b/0x1d
 [<60232844>] irq_work_run_list+0x11a/0x13a
 [<602328b4>] irq_work_tick+0x24/0x34
 [<6017f9dc>] update_process_times+0x162/0x196
 [<6019f335>] tick_sched_handle+0x1a4/0x1c3
 [<6019fd9e>] tick_sched_timer+0x79/0x10c
 [<601812b9>] __hrtimer_run_queues.constprop.0+0x425/0x695
 [<60182913>] hrtimer_interrupt+0x16c/0x2c4
 [<600486a3>] um_timer+0x164/0x183
 [...]

Allocated by task 411:
 save_stack_trace+0x99/0xb5
 stack_trace_save+0x81/0x9b
 kasan_save_stack+0x2d/0x54
 kasan_set_track+0x34/0x3e
 kasan_save_alloc_info+0x25/0x28
 ____kasan_kmalloc+0x8b/0x97
 __kasan_kmalloc+0x10/0x12
 __kmalloc+0xb2/0xe8
 load_elf_phdrs+0xee/0x182
 [...]

The buggy address belongs to the object at 000000006d640800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 584 bytes inside of
 freed 1024-byte region [000000006d640800, 000000006d640c00)

Add the appropriate irqworksync() so the work finishes before the buffers are destroyed.

Prior to the commit in the Fixes tag below, there was only a single global IRQ work, so this issue didn't exist.