On Fri, Apr 2, 2021 at 2:41 AM 'Yonghong Song' via syzkaller-bugs <syzkaller-bugs@xxxxxxxxxxxxxxxx> wrote: > > On 4/1/21 4:29 AM, syzbot wrote: > >> Hello, > >> > >> syzbot found the following issue on: > >> > >> HEAD commit: 36e79851 libbpf: Preserve empty DATASEC BTFs during > >> static.. > >> git tree: bpf-next > >> console output: > >> https://syzkaller.appspot.com/x/log.txt?x=1569bb06d00000 > >> kernel config: > >> https://syzkaller.appspot.com/x/.config?x=7eff0f22b8563a5f > >> dashboard link: > >> https://syzkaller.appspot.com/bug?extid=774c590240616eaa3423 > >> syz repro: > >> https://syzkaller.appspot.com/x/repro.syz?x=17556b7cd00000 > >> C reproducer: > >> https://syzkaller.appspot.com/x/repro.c?x=1772be26d00000 > >> > >> The issue was bisected to: > >> > >> commit 997acaf6b4b59c6a9c259740312a69ea549cc684 > >> Author: Mark Rutland <mark.rutland@xxxxxxx> > >> Date: Mon Jan 11 15:37:07 2021 +0000 > >> > >> lockdep: report broken irq restoration > >> > >> bisection log: > >> https://syzkaller.appspot.com/x/bisect.txt?x=10197016d00000 > >> final oops: > >> https://syzkaller.appspot.com/x/report.txt?x=12197016d00000 > >> console output: > >> https://syzkaller.appspot.com/x/log.txt?x=14197016d00000 > >> > >> IMPORTANT: if you fix the issue, please add the following tag to the > >> commit: > >> Reported-by: syzbot+774c590240616eaa3423@xxxxxxxxxxxxxxxxxxxxxxxxx > >> Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration") > >> > >> ------------[ cut here ]------------ > >> WARNING: CPU: 0 PID: 8725 at include/linux/bpf-cgroup.h:193 > >> bpf_cgroup_storage_set include/linux/bpf-cgroup.h:193 [inline] > >> WARNING: CPU: 0 PID: 8725 at include/linux/bpf-cgroup.h:193 > >> bpf_test_run+0x65e/0xaa0 net/bpf/test_run.c:109 > > > > I will look at this issue. Thanks! > > > >> Modules linked in: > >> CPU: 0 PID: 8725 Comm: syz-executor927 Not tainted > >> 5.12.0-rc4-syzkaller #0 > >> Hardware name: Google Google Compute Engine/Google Compute Engine, > >> BIOS Google 01/01/2011 > >> RIP: 0010:bpf_cgroup_storage_set include/linux/bpf-cgroup.h:193 [inline] > >> RIP: 0010:bpf_test_run+0x65e/0xaa0 net/bpf/test_run.c:109 > >> Code: e9 29 fe ff ff e8 b2 9d 3a fa 41 83 c6 01 bf 08 00 00 00 44 89 > >> f6 e8 51 a5 3a fa 41 83 fe 08 0f 85 74 fc ff ff e8 92 9d 3a fa <0f> 0b > >> bd f0 ffff ff e9 5c fd ff ff e8 81 9d 3a fa 83 c5 01 bf 08 > >> RSP: 0018:ffffc900017bfaf0 EFLAGS: 00010293 > >> RAX: 0000000000000000 RBX: ffffc90000f29000 RCX: 0000000000000000 > >> RDX: ffff88801bc68000 RSI: ffffffff8739543e RDI: 0000000000000003 > >> RBP: 0000000000000007 R08: 0000000000000008 R09: 0000000000000001 > >> R10: ffffffff8739542f R11: 0000000000000000 R12: dffffc0000000000 > >> R13: ffff888021dd54c0 R14: 0000000000000008 R15: 0000000000000000 > >> FS: 00007f00157d7700(0000) GS:ffff8880b9c00000(0000) > >> knlGS:0000000000000000 > >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> CR2: 00007f0015795718 CR3: 00000000157ae000 CR4: 00000000001506f0 > >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > >> Call Trace: > >> bpf_prog_test_run_skb+0xabc/0x1c70 net/bpf/test_run.c:628 > >> bpf_prog_test_run kernel/bpf/syscall.c:3132 [inline] > >> __do_sys_bpf+0x218b/0x4f40 kernel/bpf/syscall.c:4411 > >> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > > Run on my qemu (4 cpus) with C reproducer and I cannot reproduce the > result. It already ran 30 minutes and still running. Checked the code, > it is just doing a lot of parallel bpf_prog_test_run's. > > The failure is in the below WARN_ON_ONCE code: > > 175 static inline int bpf_cgroup_storage_set(struct bpf_cgroup_storage > 176 > *storage[MAX_BPF_CGROUP_STORAGE_TYPE]) > 177 { > 178 enum bpf_cgroup_storage_type stype; > 179 int i, err = 0; > 180 > 181 preempt_disable(); > 182 for (i = 0; i < BPF_CGROUP_STORAGE_NEST_MAX; i++) { > 183 if > (unlikely(this_cpu_read(bpf_cgroup_storage_info[i].task) != NULL)) > 184 continue; > 185 > 186 this_cpu_write(bpf_cgroup_storage_info[i].task, > current); > 187 for_each_cgroup_storage_type(stype) > 188 > this_cpu_write(bpf_cgroup_storage_info[i].storage[stype], > 189 storage[stype]); > 190 goto out; > 191 } > 192 err = -EBUSY; > 193 WARN_ON_ONCE(1); > 194 > 195 out: > 196 preempt_enable(); > 197 return err; > 198 } > > Basically it shows the stress test triggered a warning due to > limited kernel resource. Hi Yonghong, Thanks for looking into this. If this is not a kernel bug, then it must not use WARN_ON[_ONCE]. It makes the kernel untestable for both automated systems and humans: https://lwn.net/Articles/769365/ <quote> Greg Kroah-Hartman raised the problem of core kernel API code that will use WARN_ON_ONCE() to complain about bad usage; that will not generate the desired result if WARN_ON_ONCE() is configured to crash the machine. He was told that the code should just call pr_warn() instead, and that the called function should return an error in such situations. It was generally agreed that any WARN_ON() or WARN_ON_ONCE() calls that can be triggered from user space need to be fixed. </quote> > >> entry_SYSCALL_64_after_hwframe+0x44/0xae > >> RIP: 0033:0x446199 > >> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 48 89 f8 48 > >> 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d > >> 01 f0 ffff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > >> RSP: 002b:00007f00157d72f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > >> RAX: ffffffffffffffda RBX: 00000000004cb440 RCX: 0000000000446199 > >> RDX: 0000000000000028 RSI: 0000000020000080 RDI: 000000000000000a > >> RBP: 000000000049b074 R08: 0000000000000000 R09: 0000000000000000 > >> R10: 0000000000000000 R11: 0000000000000246 R12: f9abde7200f522cd > >> R13: 3952ddf3af240c07 R14: 1631e0d82d3fa99d R15: 00000000004cb448 > >> > >> > >> --- > >> This report is generated by a bot. It may contain errors. > >> See > >> https://goo.gl/tpsmEJ > >> for more information about syzbot. > >> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > >> > >> syzbot will keep track of this issue. See: > >> https://goo.gl/tpsmEJ#status > >> for how to communicate with syzbot. > >> For information about bisection process see: > >> https://goo.gl/tpsmEJ#bisection > >> syzbot can test patches for this issue, for details see: > >> https://goo.gl/tpsmEJ#testing-patches
