[syzbot] general protection fault in reweight_entity

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6441998e2e37 Merge tag 'audit-pr-20211216' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1305d47eb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=fa556098924b78f0
dashboard link: https://syzkaller.appspot.com/bug?extid=8d9571494fc49db5aca1
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14a88443b00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10e5179db00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8d9571...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000014: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000a0-0x00000000000000a7]
CPU: 1 PID: 18467 Comm: syz-executor672 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:dequeue_load_avg kernel/sched/fair.c:3033 [inline]
RIP: 0010:dequeue_load_avg kernel/sched/fair.c:3033 [inline] kernel/sched/fair.c:3052
RIP: 0010:reweight_entity+0x152/0x430 kernel/sched/fair.c:3052 kernel/sched/fair.c:3052
Code: 03 80 3c 11 00 0f 85 ba 02 00 00 48 8d bd a0 00 00 00 4c 8b ab e0 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 <80> 3c 11 00 0f 85 6a 02 00 00 48 8b 95 a0 00 00 00 4c 29 ea 0f 82
RSP: 0018:ffffc9000b6c7d68 EFLAGS: 00010006
RAX: 0000000000003c00 RBX: ffff888020bcba80 RCX: 0000000000000014
RDX: dffffc0000000000 RSI: ffff888020bcba80 RDI: 00000000000000a0
RBP: 0000000000000000 R08: ffff888020bcbe0c R09: ffff88801f2e8000
R10: ffff888020bcbc90 R11: ffff888020bcba70 R12: ffff888020bcbab8
R13: 0000000000000400 R14: 0000000000000000 R15: ffff8880b9c3a7d8
FS: 00007feccbab3700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd630085f8 CR3: 0000000074a55000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
reweight_task+0x94/0x160 kernel/sched/fair.c:3077 kernel/sched/fair.c:3077
set_load_weight kernel/sched/core.c:1225 [inline]
set_load_weight kernel/sched/core.c:1225 [inline] kernel/sched/core.c:6882
set_user_nice.part.0+0x837/0x1120 kernel/sched/core.c:6882 kernel/sched/core.c:6882
set_one_prio+0x241/0x340 kernel/sys.c:198 kernel/sys.c:198
__do_sys_setpriority+0x309/0xab0 kernel/sys.c:239 kernel/sys.c:239
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_x64 arch/x86/entry/common.c:50 [inline] arch/x86/entry/common.c:80
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7feccbb01819
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 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007feccbab3318 EFLAGS: 00000246 ORIG_RAX: 000000000000008d
RAX: ffffffffffffffda RBX: 00007feccbb893e8 RCX: 00007feccbb01819
RDX: 0000000000008f82 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 00007feccbb893e0 R08: 00007feccbab3700 R09: 0000000000000000
R10: 00007feccbab3700 R11: 0000000000000246 R12: 00007feccbb893ec
R13: 00007ffd6300859f R14: 00007feccbab3400 R15: 0000000000022000
</TASK>
Modules linked in:
---[ end trace ef3b708bbc5cad7f ]---
RIP: 0010:dequeue_load_avg kernel/sched/fair.c:3033 [inline]
RIP: 0010:dequeue_load_avg kernel/sched/fair.c:3033 [inline] kernel/sched/fair.c:3052
RIP: 0010:reweight_entity+0x152/0x430 kernel/sched/fair.c:3052 kernel/sched/fair.c:3052
Code: 03 80 3c 11 00 0f 85 ba 02 00 00 48 8d bd a0 00 00 00 4c 8b ab e0 00 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 <80> 3c 11 00 0f 85 6a 02 00 00 48 8b 95 a0 00 00 00 4c 29 ea 0f 82
RSP: 0018:ffffc9000b6c7d68 EFLAGS: 00010006
RAX: 0000000000003c00 RBX: ffff888020bcba80 RCX: 0000000000000014
RDX: dffffc0000000000 RSI: ffff888020bcba80 RDI: 00000000000000a0
RBP: 0000000000000000 R08: ffff888020bcbe0c R09: ffff88801f2e8000
R10: ffff888020bcbc90 R11: ffff888020bcba70 R12: ffff888020bcbab8
R13: 0000000000000400 R14: 0000000000000000 R15: ffff8880b9c3a7d8
FS: 00007feccbab3700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd630085f8 CR3: 0000000074a55000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 03 80 3c 11 00 0f add 0xf00113c(%rax),%eax
6: 85 ba 02 00 00 48 test %edi,0x48000002(%rdx)
c: 8d bd a0 00 00 00 lea 0xa0(%rbp),%edi
12: 4c 8b ab e0 00 00 00 mov 0xe0(%rbx),%r13
19: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
20: fc ff df
23: 48 89 f9 mov %rdi,%rcx
26: 48 c1 e9 03 shr $0x3,%rcx
* 2a: 80 3c 11 00 cmpb $0x0,(%rcx,%rdx,1) <-- trapping instruction
2e: 0f 85 6a 02 00 00 jne 0x29e
34: 48 8b 95 a0 00 00 00 mov 0xa0(%rbp),%rdx
3b: 4c 29 ea sub %r13,%rdx
3e: 0f .byte 0xf
3f: 82 .byte 0x82
----------------
Code disassembly (best guess):
0: 03 80 3c 11 00 0f add 0xf00113c(%rax),%eax
6: 85 ba 02 00 00 48 test %edi,0x48000002(%rdx)
c: 8d bd a0 00 00 00 lea 0xa0(%rbp),%edi
12: 4c 8b ab e0 00 00 00 mov 0xe0(%rbx),%r13
19: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
20: fc ff df
23: 48 89 f9 mov %rdi,%rcx
26: 48 c1 e9 03 shr $0x3,%rcx
* 2a: 80 3c 11 00 cmpb $0x0,(%rcx,%rdx,1) <-- trapping instruction
2e: 0f 85 6a 02 00 00 jne 0x29e
34: 48 8b 95 a0 00 00 00 mov 0xa0(%rbp),%rdx
3b: 4c 29 ea sub %r13,%rdx
3e: 0f .byte 0xf
3f: 82 .byte 0x82


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit 13765de8148f71fa795e0a6607de37c49ea5915a
Author: Tadeusz Struk <tadeus...@linaro.org>
Date: Thu Feb 3 16:18:46 2022 +0000

sched/fair: Fix fault in reweight_entity

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1230bdd9700000
start commit: b81b1829e7e3 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45
dashboard link: https://syzkaller.appspot.com/bug?extid=8d9571494fc49db5aca1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10209674700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1645552c700000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: sched/fair: Fix fault in reweight_entity

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Dmitry Vyukov]

Yes, it is: