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KCSAN: data-race in fat16_ent_put / fat_mirror_bhs

Status: moderation: reported on 2025/04/25 15:47
Subsystems: exfat
[Documentation on labels]
Reported-by: syzbot+018e6f695ad9bccb182a@syzkaller.appspotmail.com
First crash: 367d, last: 21h49m
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
bbf85b1a-acd3-4058-845d-a87b4a0ca982 repro ❓ KCSAN: data-race in fat16_ent_put / fat_mirror_bhs 2026/03/08 03:20 2026/03/08 03:20 2026/03/08 03:25 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
778a8b17-2e6a-4e72-b2d0-8bd7df6b252d assessment-kcsan Benign: ✅  Confident: ✅  ❓ KCSAN: data-race in fat16_ent_put / fat_mirror_bhs 2026/02/24 21:54 2026/02/24 21:54 2026/02/24 21:58 305c0ec5cd886e2d13738e28e1b2df9b0ec20fc9
a599f2d2-1ae0-4fa7-b423-8f638f704dff assessment-kcsan 💥 KCSAN: data-race in fat16_ent_put / fat_mirror_bhs 2026/01/10 04:47 2026/01/10 04:47 2026/01/10 04:47 7519916073b761ced56a7b15fdeeb4674e8dc125 Error 429, Message: You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit. * Quota exceeded for metric: generativelanguage.googleapis.com/generate_requests_per_model_per_day, limit: 0, Status: RESOURCE_EXHAUSTED, Details: [map[@type:type.googleapis.com/google.rpc.Help links:[map[description:Learn more about Gemini API quotas url:https://ai.google.dev/gemini-api/docs/rate-limits]]] map[@type:type.googleapis.com/google.rpc.QuotaFailure violations:[map[quotaId:GenerateRequestsPerDayPerProjectPerModel quotaMetric:generativelanguage.googleapis.com/generate_requests_per_model_per_day]]] map[@type:type.googleapis.com/google.rpc.DebugInfo detail:[ORIGINAL ERROR] generic::resource_exhausted: You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit. * Quota exceeded for metric: generativelanguage.googleapis.com/generate_requests_per_model_per_day, limit: 0 [google.rpc.error_details_ext] { message: "You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit. \n* Quota exceeded for metric: generativelanguage.googleapis.com/generate_requests_per_model_per_day, limit: 0" details { type_url: "type.googleapis.com/language_labs.genai.debug.GeminiApiDebugInfo" value: "RM\nK\nEgenerativelanguage.googleapis.com/generate_requests_per_model_per_day\030\000\"\000" } details { [type.googleapis.com/google.rpc.Help] { links { description: "Learn more about Gemini API quotas" url: "https://ai.google.dev/gemini-api/docs/rate-limits" } } } details { [type.googleapis.com/google.rpc.QuotaFailure] { violations { quota_metric: "generativelanguage.googleapis.com/generate_requests_per_model_per_day" quota_id: "GenerateRequestsPerDayPerProjectPerModel" } } } }]]

Sample crash report:
loop6: detected capacity change from 0 to 8192
==================================================================
BUG: KCSAN: data-race in fat16_ent_put / fat_mirror_bhs

write to 0xffff8881204b12a8 of 2 bytes by task 9821 on cpu 1:
 fat16_ent_put+0x28/0x60 fs/fat/fatent.c:185
 fat_alloc_clusters+0x57b/0xc50 fs/fat/fatent.c:508
 fat_add_cluster fs/fat/inode.c:108 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x25e/0x5f0 fs/fat/inode.c:190
 __block_write_begin_int+0x400/0xf90 fs/buffer.c:2042
 block_write_begin fs/buffer.c:2153 [inline]
 cont_write_begin+0x5fe/0x970 fs/buffer.c:2491
 fat_write_begin+0x52/0xe0 fs/fat/inode.c:230
 generic_perform_write+0x183/0x490 mm/filemap.c:4325
 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4442
 generic_file_write_iter+0x8d/0x310 mm/filemap.c:4468
 aio_write+0x2fe/0x430 fs/aio.c:1688
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0xbc1/0x1350 fs/aio.c:2107
 __do_sys_io_submit fs/aio.c:2166 [inline]
 __se_sys_io_submit+0xfb/0x280 fs/aio.c:2136
 __x64_sys_io_submit+0x43/0x50 fs/aio.c:2136
 x64_sys_call+0x19d5/0x3020 arch/x86/include/generated/asm/syscalls_64.h:210
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881204b1200 of 512 bytes by task 9789 on cpu 0:
 fat_mirror_bhs+0x1df/0x330 fs/fat/fatent.c:399
 fat_alloc_clusters+0xb48/0xc50 fs/fat/fatent.c:548
 fat_add_cluster fs/fat/inode.c:108 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x25e/0x5f0 fs/fat/inode.c:190
 __block_write_begin_int+0x400/0xf90 fs/buffer.c:2042
 block_write_begin fs/buffer.c:2153 [inline]
 cont_write_begin+0x5fe/0x970 fs/buffer.c:2491
 fat_write_begin+0x52/0xe0 fs/fat/inode.c:230
 generic_perform_write+0x183/0x490 mm/filemap.c:4325
 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4442
 generic_file_write_iter+0x8d/0x310 mm/filemap.c:4468
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x5a6/0x9f0 fs/read_write.c:688
 ksys_write+0xdc/0x1a0 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:748
 x64_sys_call+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9789 Comm: syz.6.1425 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================

Crashes (724):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/27 13:17 upstream 254f49634ee1 0f700595 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/25 22:25 upstream 897d54018cc9 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/24 13:34 upstream dd6c438c3e64 1c2b9291 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/21 18:41 upstream 4ee64205ffaa 0b6ab7ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/21 16:29 upstream b4e07588e743 0b6ab7ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/18 05:01 upstream 8541d8f725c6 5be7a9de .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/17 16:42 upstream 43cfbdda5af6 24ecfc1e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/14 01:34 upstream 26ff969926a0 1a086e7c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/13 12:06 upstream 028ef9c96e96 9530ccf9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/12 21:46 upstream f5459048c38a 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/09 13:09 upstream 7f87a5ea75f0 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/08 00:08 upstream 3036cd0d3328 2c961e87 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/07 12:26 upstream bfe62a454542 628666c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/06 23:55 upstream bfe62a454542 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/05 03:35 upstream 3aae9383f42f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/04 12:37 upstream 631919fb12fe 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/04/04 00:03 upstream d8a9a4b11a13 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/30 03:04 upstream a3d97d1d3fa6 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/28 18:28 upstream cbfffcca2bf0 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/28 00:08 upstream 7df48e363130 74a13a23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/26 00:42 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/24 21:05 upstream c369299895a5 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/19 15:35 upstream 8a30aeb0d1b4 bd6dcb30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/19 15:34 upstream 8a30aeb0d1b4 bd6dcb30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/18 11:13 upstream a989fde763f4 0199f9a1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/17 08:02 upstream 2d1373e4246d c01bca74 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/17 05:49 upstream 2d1373e4246d 0737c18f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/12 02:02 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/11 15:29 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/11 02:11 upstream b4f0dd314b39 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/10 18:03 upstream 1f318b96cc84 4683d576 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/10 01:46 upstream 1f318b96cc84 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/09 19:55 upstream 1f318b96cc84 176bead5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/08 21:56 upstream 014441d1e4b2 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/08 07:54 upstream c23719abc330 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/07 18:46 upstream 4ae12d8bd9a8 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/06 21:58 upstream 651690480a96 41d8037d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/06 03:05 upstream 5ee8dbf54602 31e9c887 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/06 03:04 upstream 5ee8dbf54602 31e9c887 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/04 13:24 upstream 0031c06807cf e6b6b96b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/04 03:14 upstream 0031c06807cf 4180d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/03/03 18:32 upstream af4e9ef3d784 4180d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/28 07:16 upstream 4d349ee5c778 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/22 17:32 upstream 32a92f8c8932 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/22 00:58 upstream fa5c82f4d2bb 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/18 10:21 upstream 2961f841b025 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/18 01:36 upstream d295082ea672 06ec4f7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/10 02:38 upstream 372800cb95a3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2025/04/25 15:47 upstream 02ddfb981de8 e3715315 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
* Struck through repros no longer work on HEAD.