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KCSAN: data-race in __ext4_new_inode / find_next_zero_bit

Status: closed as invalid on 2019/10/15 15:50
Subsystems: ext4
[Documentation on labels]
First crash: 2452d, last: 2442d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __ext4_new_inode / find_next_zero_bit (3) ext4 6 106 2320d 2357d 0/29 auto-closed as invalid on 2020/04/23 13:26
upstream KCSAN: data-race in __ext4_new_inode / find_next_zero_bit (4) ext4 6 1337 1871d 2186d 0/29 auto-closed as invalid on 2021/06/04 08:21
upstream KCSAN: data-race in __ext4_new_inode / find_next_zero_bit (2) ext4 6 37 2406d 2435d 0/29 closed as invalid on 2019/11/19 14:04

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __ext4_new_inode / find_next_zero_bit

write to 0xffff888120ea6010 of 8 bytes by task 7740 on cpu 1:
 __test_and_set_bit include/asm-generic/bitops-instrumented.h:168 [inline]
 __test_and_set_bit_le include/asm-generic/bitops/le.h:90 [inline]
 __ext4_new_inode+0xf54/0x3070 fs/ext4/ialloc.c:944
 ext4_symlink+0x30e/0x970 fs/ext4/namei.c:3262
 vfs_symlink fs/namei.c:4127 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4113
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4154
 __do_sys_symlink fs/namei.c:4173 [inline]
 __se_sys_symlink fs/namei.c:4171 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4171
 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120ea6010 of 8 bytes by task 7742 on cpu 0:
 _find_next_bit lib/find_bit.c:39 [inline]
 find_next_zero_bit+0x4e/0xe0 lib/find_bit.c:79
 find_next_zero_bit_le include/asm-generic/bitops/le.h:15 [inline]
 find_inode_bit.isra.0+0x82/0x300 fs/ext4/ialloc.c:715
 __ext4_new_inode+0xd4b/0x3070 fs/ext4/ialloc.c:914
 ext4_symlink+0x30e/0x970 fs/ext4/namei.c:3262
 vfs_symlink fs/namei.c:4127 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4113
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4154
 __do_sys_symlink fs/namei.c:4173 [inline]
 __se_sys_symlink fs/namei.c:4171 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4171
 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7742 Comm: syz-executor.4 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/10/14 12:33 https://github.com/google/ktsan.git kcsan d724f94f63de a6aef847 .config console log report ci2-upstream-kcsan-gce
2019/10/13 12:42 https://github.com/google/ktsan.git kcsan d724f94f63de 2f661ec4 .config console log report ci2-upstream-kcsan-gce
2019/10/08 13:47 https://github.com/google/ktsan.git kcsan 3675607974a2 137e37ca .config console log report ci2-upstream-kcsan-gce
2019/10/04 17:58 https://github.com/google/ktsan.git kcsan b4bd934316dc c86336cf .config console log report ci2-upstream-kcsan-gce
* Struck through repros no longer work on HEAD.