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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: 316d, last: 1h18m
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
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:
==================================================================
BUG: KCSAN: data-race in fat16_ent_put / fat_mirror_bhs

write to 0xffff8881456dd9dc of 2 bytes by task 12133 on cpu 0:
 fat16_ent_put+0x28/0x60 fs/fat/fatent.c:183
 fat_ent_write+0x6c/0xe0 fs/fat/fatent.c:417
 fat_chain_add+0x16c/0x490 fs/fat/misc.c:136
 fat_add_cluster fs/fat/inode.c:113 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x46c/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x400/0xf90 fs/buffer.c:2142
 block_write_begin fs/buffer.c:2253 [inline]
 cont_write_begin+0x5fe/0x970 fs/buffer.c:2591
 fat_write_begin+0x4f/0xe0 fs/fat/inode.c:230
 generic_perform_write+0x183/0x490 mm/filemap.c:4319
 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4436
 generic_file_write_iter+0x8d/0x310 mm/filemap.c:4462
 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/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881456dd800 of 512 bytes by task 12141 on cpu 1:
 fat_mirror_bhs+0x1df/0x320 fs/fat/fatent.c:395
 fat_ent_write+0xd0/0xe0 fs/fat/fatent.c:423
 fat_chain_add+0x16c/0x490 fs/fat/misc.c:136
 fat_add_cluster fs/fat/inode.c:113 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x46c/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x400/0xf90 fs/buffer.c:2142
 block_write_begin fs/buffer.c:2253 [inline]
 cont_write_begin+0x5fe/0x970 fs/buffer.c:2591
 fat_write_begin+0x4f/0xe0 fs/fat/inode.c:230
 generic_perform_write+0x183/0x490 mm/filemap.c:4319
 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4436
 generic_file_write_iter+0x8d/0x310 mm/filemap.c:4462
 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/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12141 Comm: syz.1.2846 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================

Crashes (684):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
2026/02/17 07:48 upstream 970296997869 e439b951 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/16 17:14 upstream 0f2acd3148e0 5d52cba5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/16 00:56 upstream 26a4cfaff82a 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/15 10:57 upstream ca4ee40bf13d 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/15 10:54 upstream ca4ee40bf13d 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/14 21:42 upstream 3e48a11675c5 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/14 14:08 upstream 770aaedb461a 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/13 20:35 upstream cee73b1e840c 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/13 11:12 upstream 37a93dd5c49b 6a673c50 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/13 01:30 upstream 37a93dd5c49b 504cb1bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/10 20:57 upstream 72c395024dac 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/10 03:36 upstream 8a5203c630c6 4ab09a02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/09 20:43 upstream 05f7e89ab973 df949cd9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/08 16:15 upstream e7aa57247700 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/07 03:04 upstream 2687c848e578 f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/06 14:03 upstream b7ff7151e653 97745f52 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/05 22:24 upstream 8fdb05de0e2d f03c4191 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/05 18:55 upstream 8fdb05de0e2d 4936e85c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/05 09:57 upstream f14faaf3a1fb 4936e85c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/04 17:24 upstream 5fd0a1df5d05 ea10c935 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/04 00:10 upstream de0674d9bc69 42b01fab .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/03 21:07 upstream 6bd9ed02871f 6df4c87a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/02 22:45 upstream dee65f79364c d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/02 10:17 upstream 18f7fcd5e69a 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/01 21:20 upstream 9f2693489ef8 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/02/01 02:33 upstream ad9a728a3388 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/31 19:09 upstream ad9a728a3388 afc0c4d4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/31 02:42 upstream 283073725700 c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/31 00:53 upstream 4d310797262f c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/30 13:50 upstream 4d310797262f ae7dc18c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/30 10:22 upstream 4d310797262f bfa73b7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/29 11:33 upstream 8dfce8991b95 aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fat16_ent_put / fat_mirror_bhs
2026/01/29 05:36 upstream 8dfce8991b95 0adc945e .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.