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References: <6773ed41.050a0220.25abdd.08f6.GAE@google.com> Content-Language: en-US From: Eric Dumazet In-Reply-To: <6773ed41.050a0220.25abdd.08f6.GAE@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12/31/24 2:10 PM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: ccb98ccef0e5 Merge tag 'platform-drivers-x86-v6.13-4' of g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=14d4f50f980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=86dd15278dbfe19f > dashboard link: https://syzkaller.appspot.com/bug?extid=43f6243d6c4946b26405 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-ccb98cce.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/75a6223b351c/vmlinux-ccb98cce.xz > kernel image: https://storage.googleapis.com/syzbot-assets/beea89d50f58/bzImage-ccb98cce.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+43f6243d6c4946b26405@syzkaller.appspotmail.com > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor write access in kernel mode > #PF: error_code(0x0002) - not-present page > PGD 6a754067 P4D 6a754067 PUD 68142067 PMD 0 > Oops: Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI > CPU: 0 UID: 0 PID: 7523 Comm: syz.2.395 Not tainted 6.13.0-rc5-syzkaller-00004-gccb98ccef0e5 #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 > RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38 > Code: e9 44 fd ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f8 48 89 d1 a4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 > RSP: 0018:ffffc9000370f8b0 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: ffffc9000370fc50 RCX: 0000000000000004 > RDX: 0000000000000004 RSI: ffff88804ef5d710 RDI: 0000000000000000 > RBP: 0000000000000004 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004 > R13: 0000000000000000 R14: 0000000000000004 R15: dffffc0000000000 > FS: 0000000000000000(0000) GS:ffff88802b400000(0063) knlGS:00000000f5080b40 > CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 000000006ba72000 CR4: 0000000000352ef0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > fuse_copy_do fs/fuse/dev.c:809 [inline] > fuse_copy_one+0x1cc/0x230 fs/fuse/dev.c:1065 > fuse_copy_args+0x109/0x690 fs/fuse/dev.c:1083 > copy_out_args fs/fuse/dev.c:1966 [inline] > fuse_dev_do_write+0x1b0a/0x3100 fs/fuse/dev.c:2052 > fuse_dev_write+0x160/0x1f0 fs/fuse/dev.c:2087 > new_sync_write fs/read_write.c:586 [inline] > vfs_write+0x5ae/0x1150 fs/read_write.c:679 > ksys_write+0x12b/0x250 fs/read_write.c:731 > do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] > __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 > do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 > entry_SYSENTER_compat_after_hwframe+0x84/0x8e > RIP: 0023:0xf708e579 > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > RSP: 002b:00000000f5080500 EFLAGS: 00000293 ORIG_RAX: 0000000000000004 > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000700 > RDX: 0000000000000014 RSI: 00000000f73c3ff4 RDI: 0000000000000000 > RBP: 0000000020008380 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > Modules linked in: > CR2: 0000000000000000 > ---[ end trace 0000000000000000 ]--- > RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38 > Code: e9 44 fd ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f8 48 89 d1 a4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 > RSP: 0018:ffffc9000370f8b0 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: ffffc9000370fc50 RCX: 0000000000000004 > RDX: 0000000000000004 RSI: ffff88804ef5d710 RDI: 0000000000000000 > RBP: 0000000000000004 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004 > R13: 0000000000000000 R14: 0000000000000004 R15: dffffc0000000000 > FS: 0000000000000000(0000) GS:ffff88802b400000(0063) knlGS:00000000f5080b40 > CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 000000006ba72000 CR4: 0000000000352ef0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > ---------------- > Code disassembly (best guess): > 0: e9 44 fd ff ff jmp 0xfffffd49 > 5: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1) > c: 00 00 > e: 90 nop > f: 90 nop > 10: 90 nop > 11: 90 nop > 12: 90 nop > 13: 90 nop > 14: 90 nop > 15: 90 nop > 16: 90 nop > 17: 90 nop > 18: 90 nop > 19: 90 nop > 1a: 90 nop > 1b: 90 nop > 1c: 90 nop > 1d: 90 nop > 1e: f3 0f 1e fa endbr64 > 22: 66 90 xchg %ax,%ax > 24: 48 89 f8 mov %rdi,%rax > 27: 48 89 d1 mov %rdx,%rcx > * 2a: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction > 2c: c3 ret > 2d: cc int3 > 2e: cc int3 > 2f: cc int3 > 30: cc int3 > 31: 66 66 2e 0f 1f 84 00 data16 cs nopw 0x0(%rax,%rax,1) > 38: 00 00 00 00 > 3c: 66 90 xchg %ax,%ax > 3e: 90 nop > 3f: 90 nop > > > --- > 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@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup > Bug origin in commit ebe559609d7829b52c6642b581860760984faf9d Author: Al Viro Date:   Fri Nov 15 10:30:14 2024 -0500     fs: get rid of __FMODE_NONOTIFY kludge #syz test diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 19435cd2c41f..6ff94e312232 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1624,8 +1624,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)         file = anon_inode_getfile_fmode("[fanotify]", &fanotify_fops, group,                                         f_flags, FMODE_NONOTIFY);         if (IS_ERR(file)) { -               fd = PTR_ERR(file);                 put_unused_fd(fd); +               fd = PTR_ERR(file);                 goto out_destroy_group;         }         fd_install(fd, file);