Enabling kasan or kcsan in my GTX-980 equipped box will in fairly short order result in emission of a use-after-free detection gripe (no access assert in kcsan case.. same same), immediately followed by a small mushroom cloud as the kernel attempts to access the twilight zone.

The below (brought to you by me forgetting to boot nomodeset despite knowing full well that nouveau WILL muck up any testing with either of these tools:) is x86-tip, with lockdep and kasan enabled. Branch isn't really irrelevant, it explodes just as readily in master.

[ 604.071721] ================================================================== [ 604.072204] BUG: KASAN: use-after-free in dma_fence_signal_timestamp_locked+0x399/0x430 [ 604.072269] Read of size 8 at addr ffff8881fffa0b28 by task swapper/1/0 [ 604.072330] [ 604.072351] CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: G E 5.14.0.g29fb75d-tip_debug #19 [ 604.072439] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013 [ 604.072502] Call Trace: [ 604.072530] <IRQ> [ 604.072563] dump_stack_lvl+0x45/0x59 [ 604.072605] print_address_description.constprop.0+0x1f/0x140 [ 604.072650] ? dma_fence_signal_timestamp_locked+0x399/0x430 [ 604.072708] kasan_report.cold+0x83/0xdf [ 604.072761] ? dma_fence_signal_timestamp_locked+0x399/0x430 [ 604.072820] dma_fence_signal_timestamp_locked+0x399/0x430 [ 604.072865] ? perf_trace_dma_fence+0x940/0x940 [ 604.072916] ? ktime_get+0x64/0x160 [ 604.072955] ? ktime_get+0x99/0x160 [ 604.072981] nouveau_fence_signal+0x11/0x210 [nouveau] [ 604.073161] nouveau_fence_wait_uevent_handler+0x116/0x220 [nouveau] [ 604.073333] ? __lock_release+0xec/0x4e0 [ 604.073367] nvif_notify+0x276/0x4f0 [nouveau] [ 604.073490] ? nvif_notify_get+0x170/0x170 [nouveau] [ 604.073623] ? nvkm_notify_send+0x195/0x510 [nouveau] [ 604.073760] ? do_raw_spin_unlock+0x55/0x1f0 [ 604.073814] nvkm_notify_send+0x238/0x510 [nouveau] [ 604.073903] ? do_raw_spin_unlock+0x55/0x1f0 [ 604.073934] nvkm_event_send+0x1e3/0x2d0 [nouveau] [ 604.074069] ? validate_chain+0x124/0xd50 [ 604.074096] nvkm_fifo_uevent+0x60/0x70 [nouveau] [ 604.074257] ? nvkm_fifo_cevent+0x20/0x20 [nouveau] [ 604.074367] ? check_prev_add+0x20c0/0x20c0 [ 604.074409] ? mark_lock+0xc3/0xac0 [ 604.074448] gk104_fifo_intr+0x627/0x960 [nouveau] [ 604.074585] nvkm_mc_intr+0x407/0x5e0 [nouveau] [ 604.074715] ? __lock_acquire+0xad9/0x17b0 [ 604.074765] nvkm_pci_intr+0x12b/0x190 [nouveau] [ 604.074912] ? nvkm_pci_init+0x1d0/0x1d0 [nouveau] [ 604.075076] ? nvkm_pci_init+0x1d0/0x1d0 [nouveau] [ 604.075202] __handle_irq_event_percpu+0x24a/0x640 [ 604.075240] handle_irq_event+0xef/0x230 [ 604.075285] ? handle_irq_event_percpu+0x100/0x100 [ 604.075348] handle_edge_irq+0x20d/0xb70 [ 604.075408] __common_interrupt+0x94/0x1e0 [ 604.075459] common_interrupt+0x9f/0xd0 [ 604.075503] </IRQ> [ 604.075533] asm_common_interrupt+0x1e/0x40 [ 604.075576] RIP: 0010:cpuidle_enter_state+0x1f8/0x8d0 [ 604.075629] Code: 00 41 8b 77 04 bf ff ff ff ff e8 43 ef ff ff 31 ff e8 0c 15 fe fe 80 7c 24 08 00 0f 85 9e 01 00 00 e8 bc aa 22 ff fb 45 85 e4 <0f> 88 8c 02 00 00 49 63 ec 48 8d 44 6d 00 48 8d 44 85 00 48 8d 7c [ 604.075781] RSP: 0018:ffff8881009bfdc8 EFLAGS: 00000206 [ 604.075835] RAX: 0000000000701531 RBX: ffffffff83a34520 RCX: 1ffffffff078ba21 [ 604.075899] RDX: 0000000000000000 RSI: ffffffff82e83020 RDI: ffffffff82fa1660 [ 604.075962] RBP: 0000000000000003 R08: 0000000000000001 R09: ffffffff83c5f617 [ 604.076025] R10: fffffbfff078bec2 R11: 0000000000000001 R12: 0000000000000003 [ 604.076088] R13: ffff8883ce8c564c R14: 0000008ca56ecfa2 R15: ffff8883ce8c5648 [ 604.076179] ? cpuidle_enter_state+0x1f4/0x8d0 [ 604.076238] cpuidle_enter+0x4a/0xa0 [ 604.076283] cpuidle_idle_call+0x255/0x3c0 [ 604.076328] ? arch_cpu_idle_exit+0x40/0x40 [ 604.076372] ? tsc_verify_tsc_adjust+0x9c/0x2e0 [ 604.076418] ? lockdep_hardirqs_off+0x90/0xd0 [ 604.076472] do_idle+0xd7/0x140 [ 604.076513] cpu_startup_entry+0x19/0x20 [ 604.076554] start_secondary+0x250/0x2f0 [ 604.076598] ? set_cpu_sibling_map+0x1c20/0x1c20 [ 604.076657] secondary_startup_64_no_verify+0xb0/0xbb [ 604.076742] [ 604.076762] Allocated by task 2004: [ 604.076796] kasan_save_stack+0x1b/0x40 [ 604.076836] __kasan_kmalloc+0x7c/0x90 [ 604.076873] nouveau_gem_object_close+0x300/0x7f0 [nouveau] [ 604.077060] drm_gem_object_release_handle+0x69/0xf0 [drm] [ 604.077171] drm_gem_handle_delete+0x5b/0xa0 [drm] [ 604.077260] drm_ioctl_kernel+0x1a7/0x240 [drm] [ 604.077349] drm_ioctl+0x400/0x8b0 [drm] [ 604.077453] nouveau_drm_ioctl+0xec/0x230 [nouveau] [ 604.077630] __x64_sys_ioctl+0x11c/0x170 [ 604.077671] do_syscall_64+0x38/0x90 [ 604.077707] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 604.077754] [ 604.077772] Freed by task 4941: [ 604.077803] kasan_save_stack+0x1b/0x40 [ 604.077840] kasan_set_track+0x1c/0x30 [ 604.077877] kasan_set_free_info+0x20/0x30 [ 604.077917] __kasan_slab_free+0xec/0x130 [ 604.077955] slab_free_freelist_hook+0x90/0x1a0 [ 604.077999] kfree+0xcc/0x510 [ 604.078031] nouveau_gem_object_delete_work+0x7f/0xa0 [nouveau] [ 604.078215] nouveau_cli_work+0x1ec/0x330 [nouveau] [ 604.078390] process_one_work+0x89c/0x14d0 [ 604.078431] worker_thread+0x57d/0x1310 [ 604.078468] kthread+0x335/0x400 [ 604.078501] ret_from_fork+0x1f/0x30 [ 604.078537] [ 604.078555] The buggy address belongs to the object at ffff8881fffa0b00 which belongs to the cache kmalloc-96 of size 96 [ 604.078654] The buggy address is located 40 bytes inside of 96-byte region [ffff8881fffa0b00, ffff8881fffa0b60) [ 604.078747] The buggy address belongs to the page: [ 604.078790] page:000000005085aa1b refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1fffa0 [ 604.078868] flags: 0x2ffe00000000200(slab|node=0|zone=2|lastcpupid=0x7ff) [ 604.078931] raw: 02ffe00000000200 0000000000000000 dead000000000122 ffff888100042780 [ 604.078996] raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000 [ 604.079059] page dumped because: kasan: bad access detected [ 604.079107] [ 604.079125] Memory state around the buggy address: [ 604.079168] ffff8881fffa0a00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 604.079238] ffff8881fffa0a80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 604.079299] >ffff8881fffa0b00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 604.079360] ^ [ 604.079401] ffff8881fffa0b80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc [ 604.079480] ffff8881fffa0c00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc [ 604.079553] ================================================================== [ 604.079631] Disabling lock debugging due to kernel taint [ 604.079653] general protection fault, probably for non-canonical address 0xaf600177000016b5: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 604.079675] CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: G B E 5.14.0.g29fb75d-tip_debug #19 [ 604.079696] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013 [ 604.079710] RIP: 0010:queue_work_on+0x2f/0x80 [ 604.079723] Code: 41 56 41 55 49 89 f5 41 54 49 89 d4 55 89 fd 53 9c 58 fa 25 00 02 00 00 48 89 c3 75 33 be 08 00 00 00 4c 89 e7 e8 c1 dc 5b 00 <f0> 49 0f ba 2c 24 00 41 be 00 00 00 00 73 1e 48 85 db 74 06 e8 58 [ 604.079752] RSP: 0018:ffff8883ce88fa88 EFLAGS: 00010002 [ 604.079767] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81190eff [ 604.079781] RDX: 0000000000000001 RSI: 0000000000000008 RDI: af600177000016b5 [ 604.079795] RBP: 0000000000000008 R08: 0000000000000001 R09: af600177000016bd [ 604.079809] R10: fffffbfff0723948 R11: 0000000000000001 R12: af600177000016b5 [ 604.079823] R13: ffff88810005b000 R14: 1ffff11079d11f58 R15: ffff8881fffa0580 [ 604.079837] FS: 0000000000000000(0000) GS:ffff8883ce880000(0000) knlGS:0000000000000000 [ 604.079853] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 604.079866] CR2: 00007fd91d12000b CR3: 000000000782a001 CR4: 00000000001706e0 [ 604.079880] Call Trace: [ 604.079888] <IRQ> [ 604.079897] dma_fence_signal_timestamp_locked+0x213/0x430 [ 604.079915] ? perf_trace_dma_fence+0x940/0x940 [ 604.079929] ? ktime_get+0x64/0x160 [ 604.079941] ? ktime_get+0x99/0x160 [ 604.079955] nouveau_fence_signal+0x11/0x210 [nouveau] [ 604.080091] nouveau_fence_wait_uevent_handler+0x116/0x220 [nouveau] [ 604.080248] ? __lock_release+0xec/0x4e0 [ 604.080263] nvif_notify+0x276/0x4f0 [nouveau] [ 604.080398] ? nvif_notify_get+0x170/0x170 [nouveau] [ 604.080533] ? nvkm_notify_send+0x195/0x510 [nouveau] [ 604.080671] ? do_raw_spin_unlock+0x55/0x1f0 [ 604.080684] nvkm_notify_send+0x238/0x510 [nouveau] [ 604.080788] ? do_raw_spin_unlock+0x55/0x1f0 [ 604.080813] nvkm_event_send+0x1e3/0x2d0 [nouveau] [ 604.080926] ? validate_chain+0x124/0xd50 [ 604.080939] nvkm_fifo_uevent+0x60/0x70 [nouveau] [ 604.081080] ? nvkm_fifo_cevent+0x20/0x20 [nouveau] [ 604.081228] ? check_prev_add+0x20c0/0x20c0 [ 604.081239] ? mark_lock+0xc3/0xac0 [ 604.081250] gk104_fifo_intr+0x627/0x960 [nouveau] [ 604.081394] nvkm_mc_intr+0x407/0x5e0 [nouveau] [ 604.081525] ? __lock_acquire+0xad9/0x17b0 [ 604.081539] nvkm_pci_intr+0x12b/0x190 [nouveau] [ 604.081667] ? nvkm_pci_init+0x1d0/0x1d0 [nouveau] [ 604.081793] ? nvkm_pci_init+0x1d0/0x1d0 [nouveau] [ 604.081926] __handle_irq_event_percpu+0x24a/0x640 [ 604.081942] handle_irq_event+0xef/0x230 [ 604.081954] ? handle_irq_event_percpu+0x100/0x100 [ 604.081968] handle_edge_irq+0x20d/0xb70 [ 604.081982] __common_interrupt+0x94/0x1e0 [ 604.081996] common_interrupt+0x9f/0xd0 [ 604.082009] </IRQ> [ 604.082017] asm_common_interrupt+0x1e/0x40 [ 604.082028] RIP: 0010:cpuidle_enter_state+0x1f8/0x8d0 [ 604.082043] Code: 00 41 8b 77 04 bf ff ff ff ff e8 43 ef ff ff 31 ff e8 0c 15 fe fe 80 7c 24 08 00 0f 85 9e 01 00 00 e8 bc aa 22 ff fb 45 85 e4 <0f> 88 8c 02 00 00 49 63 ec 48 8d 44 6d 00 48 8d 44 85 00 48 8d 7c [ 604.082070] RSP: 0018:ffff8881009bfdc8 EFLAGS: 00000206 [ 604.082083] RAX: 0000000000701531 RBX: ffffffff83a34520 RCX: 1ffffffff078ba21 [ 604.082097] RDX: 0000000000000000 RSI: ffffffff82e83020 RDI: ffffffff82fa1660 [ 604.082110] RBP: 0000000000000003 R08: 0000000000000001 R09: ffffffff83c5f617 [ 604.082123] R10: fffffbfff078bec2 R11: 0000000000000001 R12: 0000000000000003 [ 604.082137] R13: ffff8883ce8c564c R14: 0000008ca56ecfa2 R15: ffff8883ce8c5648 [ 604.082157] ? cpuidle_enter_state+0x1f4/0x8d0 [ 604.082172] cpuidle_enter+0x4a/0xa0 [ 604.082185] cpuidle_idle_call+0x255/0x3c0 [ 604.082198] ? arch_cpu_idle_exit+0x40/0x40 [ 604.082210] ? tsc_verify_tsc_adjust+0x9c/0x2e0 [ 604.082222] ? lockdep_hardirqs_off+0x90/0xd0 [ 604.082236] do_idle+0xd7/0x140 [ 604.082248] cpu_startup_entry+0x19/0x20 [ 604.082259] start_secondary+0x250/0x2f0 [ 604.082271] ? set_cpu_sibling_map+0x1c20/0x1c20 [ 604.082286] secondary_startup_64_no_verify+0xb0/0xbb [ 604.082305] Modules linked in: overlay(E) sr_mod(E) cdrom(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) xfs(E) libcrc32c(E) loop(E) af_packet(E) ip6table_mangle(E) ip6table_raw(E) iptable_raw(E) nfnetlink(E) bridge(E) ebtable_filter(E) stp(E) llc(E) ebtables(E) iscsi_ibft(E) iscsi_boot_sysfs(E) ip6table_filter(E) ip6_tables(E) rfkill(E) iptable_filter(E) ip_tables(E) x_tables(E) bpfilter(E) nls_iso8859_1(E) nls_cp437(E) usblp(E) joydev(E) intel_rapl_msr(E) intel_rapl_common(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) coretemp(E) kvm_intel(E) iTCO_wdt(E) intel_pmc_bxt(E) at24(E) mei_hdcp(E) regmap_i2c(E) iTCO_vendor_support(E) kvm(E) snd_hda_codec_realtek(E) snd_hda_codec_hdmi(E) snd_hda_codec_generic(E) ledtrig_audio(E) irqbypass(E) crct10dif_pclmul(E) crc32_pclmul(E) ghash_clmulni_intel(E) snd_hda_intel(E) snd_intel_dspcfg(E) aesni_intel(E) crypto_simd(E) cryptd(E) snd_hda_codec(E) r8169(E) snd_hwdep(E) i2c_i801(E) snd_hda_core(E) i2c_smbus(E) pcspkr(E) realtek(E) snd_pcm(E) [ 604.082429] mdio_devres(E) snd_timer(E) lpc_ich(E) snd(E) libphy(E) mei_me(E) mfd_core(E) mei(E) soundcore(E) fan(E) thermal(E) intel_smartconnect(E) sch_fq_codel(E) nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) fuse(E) configfs(E) sunrpc(E) hid_logitech_hidpp(E) hid_logitech_dj(E) uas(E) usb_storage(E) hid_generic(E) usbhid(E) nouveau(E) drm_ttm_helper(E) ttm(E) wmi(E) i2c_algo_bit(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) sysimgblt(E) fb_sys_fops(E) cec(E) rc_core(E) ahci(E) libahci(E) xhci_pci(E) drm(E) ehci_pci(E) libata(E) ehci_hcd(E) xhci_hcd(E) usbcore(E) video(E) button(E) sd_mod(E) t10_pi(E) vfat(E) fat(E) virtio_blk(E) virtio_mmio(E) virtio_ring(E) virtio(E) ext4(E) crc32c_intel(E) crc16(E) mbcache(E) jbd2(E) sg(E) dm_multipath(E) dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) scsi_mod(E) msr(E) efivarfs(E) autofs4(E) [ 604.082768] Dumping ftrace buffer: [ 604.082781] (ftrace buffer empty)