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KCSAN: data-race in __bpf_lru_list_rotate_inactive.isra.0 / __htab_lru_percpu_map_update_elem

Status: closed as invalid on 2020/06/18 14:24
Subsystems: bpf
[Documentation on labels]
First crash: 1465d, last: 1395d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __bpf_lru_list_rotate_inactive.isra.0 / __htab_lru_percpu_map_update_elem

write to 0xffff88809ae5ee23 of 1 bytes by task 14843 on cpu 1:
 bpf_lru_node_set_ref kernel/bpf/bpf_lru_list.h:70 [inline]
 __htab_lru_percpu_map_update_elem+0x40d/0x630 kernel/bpf/hashtab.c:1174
 bpf_percpu_hash_update+0x9e/0xb0 kernel/bpf/hashtab.c:1707
 bpf_map_update_value.isra.0+0x25b/0x420 kernel/bpf/syscall.c:178
 generic_map_update_batch+0x273/0x3c0 kernel/bpf/syscall.c:1326
 bpf_map_do_batch+0x194/0x3a0 kernel/bpf/syscall.c:3556
 __do_sys_bpf+0x1cca/0x3100 kernel/bpf/syscall.c:3767
 __se_sys_bpf kernel/bpf/syscall.c:3661 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3661
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88809ae5ee23 of 1 bytes by task 14839 on cpu 0:
 __bpf_lru_list_rotate_inactive.isra.0+0x122/0x1d0 kernel/bpf/bpf_lru_list.c:190
 __bpf_lru_list_rotate kernel/bpf/bpf_lru_list.c:242 [inline]
 bpf_lru_list_pop_free_to_local kernel/bpf/bpf_lru_list.c:329 [inline]
 bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:447 [inline]
 bpf_lru_pop_free+0x452/0xa30 kernel/bpf/bpf_lru_list.c:499
 prealloc_lru_pop+0x30/0x70 kernel/bpf/hashtab.c:237
 __htab_lru_percpu_map_update_elem+0x37a/0x630 kernel/bpf/hashtab.c:1160
 bpf_percpu_hash_update+0x9e/0xb0 kernel/bpf/hashtab.c:1707
 bpf_map_update_value.isra.0+0x25b/0x420 kernel/bpf/syscall.c:178
 generic_map_update_batch+0x273/0x3c0 kernel/bpf/syscall.c:1326
 bpf_map_do_batch+0x194/0x3a0 kernel/bpf/syscall.c:3556
 __do_sys_bpf+0x1cca/0x3100 kernel/bpf/syscall.c:3767
 __se_sys_bpf kernel/bpf/syscall.c:3661 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3661
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14839 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/06/02 16:31 https://github.com/google/ktsan.git kcsan 7c3cd68e5d38 52fd7b7d .config console log report ci2-upstream-kcsan-gce
2020/03/30 23:48 https://github.com/google/ktsan.git kcsan 40959e34d670 c8d1cc20 .config console log report ci2-upstream-kcsan-gce
2020/03/24 12:46 https://github.com/google/ktsan.git kcsan 40959e34d670 33e14df3 .config console log report ci2-upstream-kcsan-gce
* Struck through repros no longer work on HEAD.