linux-kernel - [syzbot] [bpf?] KCSAN: data-race in bpf_percpu_array_update / bpf_percpu_array

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Date:   Tue, 29 Aug 2023 02:39:53 -0700
From:   syzbot <syzbot+97522333291430dd277f@...kaller.appspotmail.com>
To:     andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org,
        daniel@...earbox.net, haoluo@...gle.com, john.fastabend@...il.com,
        jolsa@...nel.org, kpsingh@...nel.org, linux-kernel@...r.kernel.org,
        martin.lau@...ux.dev, sdf@...gle.com, song@...nel.org,
        syzkaller-bugs@...glegroups.com, yhs@...com
Subject: [syzbot] [bpf?] KCSAN: data-race in bpf_percpu_array_update /
 bpf_percpu_array_update (2)

Hello,

syzbot found the following issue on:

HEAD commit:    727dbda16b83 Merge tag 'hardening-v6.6-rc1' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=136f39dfa80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dea9c2ce3f646a25
dashboard link: https://syzkaller.appspot.com/bug?extid=97522333291430dd277f
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9923a023ab11/disk-727dbda1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/650dbc695d77/vmlinux-727dbda1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/361da71276bf/bzImage-727dbda1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+97522333291430dd277f@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in bpf_percpu_array_update / bpf_percpu_array_update

write to 0xffffe8fffe7425d8 of 8 bytes by task 8257 on cpu 1:
 bpf_long_memcpy include/linux/bpf.h:428 [inline]
 bpf_obj_memcpy include/linux/bpf.h:441 [inline]
 copy_map_value_long include/linux/bpf.h:464 [inline]
 bpf_percpu_array_update+0x3bb/0x500 kernel/bpf/arraymap.c:380
 bpf_map_update_value+0x190/0x370 kernel/bpf/syscall.c:175
 generic_map_update_batch+0x3ae/0x4f0 kernel/bpf/syscall.c:1749
 bpf_map_do_batch+0x2df/0x3d0 kernel/bpf/syscall.c:4648
 __sys_bpf+0x28a/0x780
 __do_sys_bpf kernel/bpf/syscall.c:5241 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5239 [inline]
 __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5239
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffffe8fffe7425d8 of 8 bytes by task 8268 on cpu 0:
 bpf_long_memcpy include/linux/bpf.h:428 [inline]
 bpf_obj_memcpy include/linux/bpf.h:441 [inline]
 copy_map_value_long include/linux/bpf.h:464 [inline]
 bpf_percpu_array_update+0x3bb/0x500 kernel/bpf/arraymap.c:380
 bpf_map_update_value+0x190/0x370 kernel/bpf/syscall.c:175
 generic_map_update_batch+0x3ae/0x4f0 kernel/bpf/syscall.c:1749
 bpf_map_do_batch+0x2df/0x3d0 kernel/bpf/syscall.c:4648
 __sys_bpf+0x28a/0x780
 __do_sys_bpf kernel/bpf/syscall.c:5241 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5239 [inline]
 __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5239
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0xfffffff000002788

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8268 Comm: syz-executor.4 Not tainted 6.5.0-syzkaller-00453-g727dbda16b83 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
==================================================================


---
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