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-0700 (PDT) Date: Fri, 01 Apr 2022 02:22:30 -0700 In-Reply-To: <00000000000065061a05d85b8262@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000062c05a05db9451e4@google.com> Subject: Re: [syzbot] KASAN: use-after-free Read in io_poll_check_events From: syzbot To: asml.silence@gmail.com, axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org syzbot has found a reproducer for the following issue on: HEAD commit: e5071887cd22 Add linux-next specific files for 20220401 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=1672d26b700000 kernel config: https://syzkaller.appspot.com/x/.config?x=17fed8f59a304eee dashboard link: https://syzkaller.appspot.com/bug?extid=edb9c7738ba8cbdbf197 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=1016f8f3700000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14907c5b700000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+edb9c7738ba8cbdbf197@syzkaller.appspotmail.com general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] CPU: 1 PID: 3567 Comm: syz-executor893 Not tainted 5.17.0-next-20220401-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:vfs_poll include/linux/poll.h:86 [inline] RIP: 0010:io_poll_check_events+0x1e0/0x800 fs/io_uring.c:5960 Code: e8 03 48 c7 44 24 60 00 00 00 00 44 89 74 24 68 42 80 3c 28 00 0f 85 ac 05 00 00 48 8b 5d 00 48 8d 7b 28 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 88 05 00 00 48 8b 43 28 48 8d 78 48 48 89 fa RSP: 0018:ffffc900038ffa00 EFLAGS: 00010206 RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88801cea0000 RSI: ffffffff81eba128 RDI: 0000000000000028 RBP: ffff8880182d28c0 R08: 0000000000000000 R09: ffff8880182d2947 R10: ffffffff81eba2f4 R11: 0000000000000006 R12: 0000000000000001 R13: dffffc0000000000 R14: 0000000040002038 R15: ffff8880182d2944 FS: 0000555556048300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff954a2e140 CR3: 000000001a5af000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: io_poll_task_func+0x41/0x500 fs/io_uring.c:5995 handle_tw_list fs/io_uring.c:2462 [inline] tctx_task_work+0x1a4/0x1460 fs/io_uring.c:2496 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 get_signal+0x1c5/0x24c0 kernel/signal.c:2681 arch_do_signal_or_restart+0x88/0x1a10 arch/x86/kernel/signal.c:867 exit_to_user_mode_loop kernel/entry/common.c:180 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:215 __syscall_exit_to_user_mode_work kernel/entry/common.c:297 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:308 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7ff9549bcff9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd1be31e78 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: 0000000000000200 RBX: 0000000000000000 RCX: 00007ff9549bcff9 RDX: 0000000000000000 RSI: 000000000000146f RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff954980880 R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:vfs_poll include/linux/poll.h:86 [inline] RIP: 0010:io_poll_check_events+0x1e0/0x800 fs/io_uring.c:5960 Code: e8 03 48 c7 44 24 60 00 00 00 00 44 89 74 24 68 42 80 3c 28 00 0f 85 ac 05 00 00 48 8b 5d 00 48 8d 7b 28 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 88 05 00 00 48 8b 43 28 48 8d 78 48 48 89 fa RSP: 0018:ffffc900038ffa00 EFLAGS: 00010206 RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88801cea0000 RSI: ffffffff81eba128 RDI: 0000000000000028 RBP: ffff8880182d28c0 R08: 0000000000000000 R09: ffff8880182d2947 R10: ffffffff81eba2f4 R11: 0000000000000006 R12: 0000000000000001 R13: dffffc0000000000 R14: 0000000040002038 R15: ffff8880182d2944 FS: 0000555556048300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff954a2e140 CR3: 000000001a5af000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: e8 03 48 c7 44 callq 0x44c74808 5: 24 60 and $0x60,%al 7: 00 00 add %al,(%rax) 9: 00 00 add %al,(%rax) b: 44 89 74 24 68 mov %r14d,0x68(%rsp) 10: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 15: 0f 85 ac 05 00 00 jne 0x5c7 1b: 48 8b 5d 00 mov 0x0(%rbp),%rbx 1f: 48 8d 7b 28 lea 0x28(%rbx),%rdi 23: 48 89 f8 mov %rdi,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 0f 85 88 05 00 00 jne 0x5bd 35: 48 8b 43 28 mov 0x28(%rbx),%rax 39: 48 8d 78 48 lea 0x48(%rax),%rdi 3d: 48 89 fa mov %rdi,%rdx