syzbot has found a reproducer for the following crash on: HEAD commit: 7cc2a8ea Merge tag 'block-5.8-2020-07-01' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14ed01a3100000 kernel config: https://syzkaller.appspot.com/x/.config?x=183dd243398ba7ec dashboard link: https://syzkaller.appspot.com/bug?extid=7748c5375dc20dfdb92f compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1469d28f100000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+7748c5375dc20dfdb92f@xxxxxxxxxxxxxxxxxxxxxxxxx BUG: sleeping function called from invalid context at arch/x86/mm/fault.c:1253 in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 6824, name: syz-executor.2 1 lock held by syz-executor.2/6824: #0: ffff88809abb82a8 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:56 [inline] #0: ffff88809abb82a8 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x344/0xba0 arch/x86/mm/fault.c:1236 irq event stamp: 190300 hardirqs last enabled at (190299): [<ffffffff881efdef>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] hardirqs last enabled at (190299): [<ffffffff881efdef>] _raw_spin_unlock_irqrestore+0x6f/0xd0 kernel/locking/spinlock.c:191 hardirqs last disabled at (190300): [<ffffffff810075c2>] __syscall_return_slowpath+0x52/0x180 arch/x86/entry/common.c:328 softirqs last enabled at (187494): [<ffffffff88200f0f>] asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 softirqs last disabled at (187473): [<ffffffff88200f0f>] asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 CPU: 0 PID: 6824 Comm: syz-executor.2 Not tainted 5.8.0-rc3-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+0x1f0/0x31e lib/dump_stack.c:118 ___might_sleep+0x3c0/0x570 kernel/sched/core.c:6899 do_user_addr_fault+0x377/0xba0 arch/x86/mm/fault.c:1253 handle_page_fault arch/x86/mm/fault.c:1365 [inline] exc_page_fault+0x124/0x1f0 arch/x86/mm/fault.c:1418 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:565 RIP: 0010:__prepare_exit_to_usermode+0x52/0x1e0 arch/x86/entry/common.c:240 Code: 24 50 15 00 00 0f 85 8f 01 00 00 f0 41 80 64 24 03 7f 83 3d 9f e9 6c 08 00 74 23 41 83 bc 24 cc 08 00 00 00 75 18 41 83 00 00 <00> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 RSP: 0018:ffffc90001607f10 EFLAGS: 00010006 RAX: 0000000000000000 RBX: 000000000000003d RCX: ffff888095318300 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90001607f58 RBP: 0000000000000000 R08: ffffffff817a2250 R09: ffffed10128c82ed R10: ffffed10128c82ed R11: 0000000000000000 R12: ffff888095318300 R13: 0000000000000000 R14: ffffc90001607f58 R15: ffffc90001607f58 do_syscall_64+0x7f/0xe0 arch/x86/entry/common.c:368 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4169ca Code: Bad RIP value. RSP: 002b:00007fff61070cd8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: 0000000000000000 RBX: 000000000000e1d1 RCX: 00000000004169ca RDX: 0000000040000001 RSI: 00007fff61070d10 RDI: ffffffffffffffff RBP: 0000000000000002 R08: 0000000000000001 R09: 0000000001cf2940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008 R13: 00007fff61070d10 R14: 000000000000de93 R15: 00007fff61070d20 BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD a7cf1067 P4D a7cf1067 PUD a0728067 PMD 0 Oops: 0002 [#1] PREEMPT SMP KASAN CPU: 0 PID: 6824 Comm: syz-executor.2 Tainted: G W 5.8.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__prepare_exit_to_usermode+0x52/0x1e0 arch/x86/entry/common.c:240 Code: 24 50 15 00 00 0f 85 8f 01 00 00 f0 41 80 64 24 03 7f 83 3d 9f e9 6c 08 00 74 23 41 83 bc 24 cc 08 00 00 00 75 18 41 83 00 00 <00> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 RSP: 0018:ffffc90001607f10 EFLAGS: 00010006 RAX: 0000000000000000 RBX: 000000000000003d RCX: ffff888095318300 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90001607f58 RBP: 0000000000000000 R08: ffffffff817a2250 R09: ffffed10128c82ed R10: ffffed10128c82ed R11: 0000000000000000 R12: ffff888095318300 R13: 0000000000000000 R14: ffffc90001607f58 R15: ffffc90001607f58 FS: 0000000001cf2940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000a380c000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: do_syscall_64+0x7f/0xe0 arch/x86/entry/common.c:368 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4169ca Code: Bad RIP value. RSP: 002b:00007fff61070cd8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: 0000000000000000 RBX: 000000000000e1d1 RCX: 00000000004169ca RDX: 0000000040000001 RSI: 00007fff61070d10 RDI: ffffffffffffffff RBP: 0000000000000002 R08: 0000000000000001 R09: 0000000001cf2940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008 R13: 00007fff61070d10 R14: 000000000000de93 R15: 00007fff61070d20 Modules linked in: CR2: 0000000000000000 ---[ end trace bee8a2ac971d1076 ]--- RIP: 0010:__prepare_exit_to_usermode+0x52/0x1e0 arch/x86/entry/common.c:240 Code: 24 50 15 00 00 0f 85 8f 01 00 00 f0 41 80 64 24 03 7f 83 3d 9f e9 6c 08 00 74 23 41 83 bc 24 cc 08 00 00 00 75 18 41 83 00 00 <00> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 RSP: 0018:ffffc90001607f10 EFLAGS: 00010006 RAX: 0000000000000000 RBX: 000000000000003d RCX: ffff888095318300 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90001607f58 RBP: 0000000000000000 R08: ffffffff817a2250 R09: ffffed10128c82ed R10: ffffed10128c82ed R11: 0000000000000000 R12: ffff888095318300 R13: 0000000000000000 R14: ffffc90001607f58 R15: ffffc90001607f58 FS: 0000000001cf2940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000a380c000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
