KASAN: vmalloc-out-of-bounds Read in init_srcu_struct_fields

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b19e8c68 Merge tag 'arm64-fixes' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=103457a5e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=735296e4dd620b10
dashboard link: https://syzkaller.appspot.com/bug?extid=7b3b38c31d9cfd7c6f85
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [k...@vger.kernel.org linux-...@vger.kernel.org pbon...@redhat.com]

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7b3b38...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in init_srcu_struct_nodes kernel/rcu/srcutree.c:150 [inline]
BUG: KASAN: vmalloc-out-of-bounds in init_srcu_struct_fields+0x101a/0x1360 kernel/rcu/srcutree.c:180
Read of size 4 at addr ffffc9001621e8e0 by task syz-executor.1/14219

CPU: 1 PID: 14219 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0x5/0x30b mm/kasan/report.c:374
__kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:641
__asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:134
init_srcu_struct_nodes kernel/rcu/srcutree.c:150 [inline]
init_srcu_struct_fields+0x101a/0x1360 kernel/rcu/srcutree.c:180
__init_srcu_struct+0x57/0x60 kernel/rcu/srcutree.c:196
kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:696 [inline]
kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3604 [inline]
kvm_dev_ioctl+0x37b/0x1520 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3656
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x123/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c6c9
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd305ec0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd305ec16d4 RCX: 000000000045c6c9
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000007
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000038b R14: 00000000004c5eab R15: 000000000076bf2c


Memory state around the buggy address:
ffffc9001621e780: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
ffffc9001621e800: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
>ffffc9001621e880: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
^
ffffc9001621e900: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
ffffc9001621e980: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.