KCSAN: data-race in mas_wr_store_entry / mtree_load

Status: upstream: reported C repro on 2026/07/26 06:43
Subsystems: kernel
Labels: race:harmful prio:high
[Documentation on labels]
Reported-by: syzbot+caa2ebc5f1f594970675@syzkaller.appspotmail.com
First crash: 62d, last: 1d19h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
e5aff4a3 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ KCSAN: data-race in mas_wr_store_entry / mtree_load 2026/07/28 01:33 2026/07/28 01:33 2026/07/28 02:13 4cb2b096
b4fafe21 assessment-kcsan Benign: ❌ ❓ KCSAN: data-race in mas_wr_store_entry / mtree_load 2026/07/26 06:15 2026/07/26 06:15 2026/07/26 06:42 492bab15
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[syzbot] [kernel?] KCSAN: data-race in mas_wr_store_entry / mtree_load 1 (3) 2026/09/24 21:15

Sample crash report:
==================================================================
BUG: KCSAN: data-race in mas_wr_store_entry / mtree_load

write to 0xffff88810493bb00 of 8 bytes by task 3643 on cpu 1:
 mte_set_node_dead lib/maple_tree.c:305 [inline]
 mas_put_in_tree lib/maple_tree.c:1652 [inline]
 mas_replace_node lib/maple_tree.c:1667 [inline]
 mas_wr_node_store lib/maple_tree.c:3276 [inline]
 mas_wr_store_entry+0x3c1f/0x5ac0 lib/maple_tree.c:3606
 mas_store_gfp+0x493/0x580 lib/maple_tree.c:4999
 irq_insert_desc kernel/irq/irqdesc.c:195 [inline]
 alloc_descs kernel/irq/irqdesc.c:531 [inline]
 __irq_alloc_descs+0x361/0x4d0 kernel/irq/irqdesc.c:922
 irq_domain_alloc_descs kernel/irq/irqdomain.c:-1 [inline]
 irq_domain_alloc_irqs_locked+0x7f/0x7d0 kernel/irq/irqdomain.c:1639
 __irq_domain_alloc_irqs+0x80/0xd0 kernel/irq/irqdomain.c:1713
 __msi_domain_alloc_irqs+0x435/0xa00 kernel/irq/msi.c:1336
 __msi_domain_alloc_locked kernel/irq/msi.c:1393 [inline]
 msi_domain_alloc_locked+0x357/0x3e0 kernel/irq/msi.c:1398
 msi_domain_alloc_irqs_all_locked+0xd2/0x110 kernel/irq/msi.c:1474
 pci_msi_setup_msi_irqs+0x7a/0x90 drivers/pci/msi/irqdomain.c:17
 __msix_setup_interrupts drivers/pci/msi/msi.c:687 [inline]
 msix_setup_interrupts drivers/pci/msi/msi.c:708 [inline]
 msix_capability_init+0x566/0x960 drivers/pci/msi/msi.c:748
 __pci_enable_msix_range+0x41d/0x4b0 drivers/pci/msi/msi.c:856
 pci_alloc_irq_vectors_affinity+0xac/0x1e0 drivers/pci/msi/api.c:268
 vp_request_msix_vectors drivers/virtio/virtio_pci_common.c:159 [inline]
 vp_find_vqs_msix+0x3f0/0x8b0 drivers/virtio/virtio_pci_common.c:416
 vp_find_vqs+0x4a/0x4a0 drivers/virtio/virtio_pci_common.c:526
 virtio_find_vqs include/linux/virtio_config.h:298 [inline]
 virtio_find_single_vq include/linux/virtio_config.h:309 [inline]
 probe_common+0x1e8/0x3c0 drivers/char/hw_random/virtio-rng.c:177
 virtrng_probe+0x15/0x20 drivers/char/hw_random/virtio-rng.c:215
 virtio_dev_probe+0x5cf/0x780 drivers/virtio/virtio.c:347
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x1ba/0x600 drivers/base/dd.c:706
 __driver_probe_device+0x14f/0x1c0 drivers/base/dd.c:868
 device_driver_attach+0x8d/0x130 drivers/base/dd.c:1203
 bind_store+0x17b/0x1c0 drivers/base/bus.c:267
 drv_attr_store+0x57/0x80 drivers/base/bus.c:125
 sysfs_kf_write+0xfe/0x120 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x1d2/0x2e0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57f/0x9a0 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810493bb00 of 8 bytes by task 3646 on cpu 0:
 ma_dead_node lib/maple_tree.c:505 [inline]
 mtree_lookup_walk lib/maple_tree.c:3049 [inline]
 mtree_load+0x3fd/0x600 lib/maple_tree.c:5822
 irq_to_desc kernel/irq/irqdesc.c:414 [inline]
 kstat_irqs kernel/irq/irqdesc.c:1027 [inline]
 kstat_irqs_usr+0x28/0x1a0 kernel/irq/irqdesc.c:1071
 show_all_irqs fs/proc/stat.c:41 [inline]
 show_stat+0x96f/0xb90 fs/proc/stat.c:135
 seq_read_iter+0x2d9/0x8f0 fs/seq_file.c:231
 proc_reg_read_iter+0xe6/0x180 fs/proc/inode.c:295
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888100b7f70e -> 0xffff88810493bb00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3646 Comm: syz-executor354 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/24 21:15 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f49a343b305c 2daa4bb5 .config console log report C ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/16 17:59 upstream 9b87fdc9af2f 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/14 19:09 upstream 704340f1cd0d 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/14 12:59 upstream 704340f1cd0d 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/12 10:19 upstream 3026c6e4f223 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/09 13:33 upstream 893e11787f78 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/01 13:10 upstream 786262be6048 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/09/01 05:51 upstream bf1079577a11 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/08/27 15:37 upstream 73e3f0710014 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/08/09 04:09 upstream a7c7074b58d2 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/08/07 16:02 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/08/04 21:38 upstream 562bfb501c54 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/07/26 14:14 upstream 3dab139d4795 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
2026/07/26 06:15 upstream 0ce37745d4bf 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in mas_wr_store_entry / mtree_load
* Struck through repros no longer work on HEAD.