[syzbot] [mm?] general protection fault in mremap

[syzbot <syzbot+5250c4727db03e3436cc@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    a2cc6ff5ec8f Merge tag 'firewire-updates-6.15' of git://gi..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11ab27cf980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=adffebefc9feb9d6
dashboard link: https://syzkaller.appspot.com/bug?extid=5250c4727db03e3436cc
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1693d404580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=178ac94c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8ecd2318067e/disk-a2cc6ff5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/05691b82062c/vmlinux-a2cc6ff5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4698994e99d4/bzImage-a2cc6ff5.xz

The issue was bisected to:

commit d5c8aec0542e2d79b64de9089b88fabdebe05c1e
Author: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Date:   Mon Mar 10 20:50:37 2025 +0000

    mm/mremap: initial refactor of move_vma()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11ff2a74580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13ff2a74580000
console output: https://syzkaller.appspot.com/x/log.txt?x=15ff2a74580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5250c4727db03e3436cc@syzkaller.appspotmail.com
Fixes: d5c8aec0542e ("mm/mremap: initial refactor of move_vma()")

Code: 48 83 c4 28 c3 e8 17 1a 00 00 0f 1f 80 00 00 00 00 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:00007fff0b8738c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
RAX: ffffffffffffffda RBX: 00007fff0b8738d0 RCX: 00007f46ffb182e9
RDX: 0000000000003000 RSI: 0000000000001000 RDI: 0000200000ffc000
RBP: 0000000000000001 R08: 0000200000ffa000 R09: 00007f46ffb80031
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f46ffb83618
R13: 00007fff0b873aa8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 0 UID: 0 PID: 5820 Comm: syz-executor115 Not tainted 6.14.0-syzkaller-12966-ga2cc6ff5ec8f #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:vrm_uncharge mm/mremap.c:964 [inline]
RIP: 0010:expand_vma_in_place mm/mremap.c:1566 [inline]
RIP: 0010:expand_vma mm/mremap.c:1621 [inline]
RIP: 0010:mremap_at mm/mremap.c:1682 [inline]
RIP: 0010:do_mremap mm/mremap.c:1727 [inline]
RIP: 0010:__do_sys_mremap+0x1392/0x15c0 mm/mremap.c:1784
Code: 0f 85 45 02 00 00 48 8b 04 24 c6 84 24 70 01 00 00 01 48 01 85 68 02 00 00 eb 9a e8 18 34 af ff 48 b8 04 00 00 00 00 fc ff df <80> 38 00 0f 85 a7 01 00 00 48 8b 2c 25 20 00 00 00 31 ff 81 e5 00
RSP: 0018:ffffc900039dfd20 EFLAGS: 00010293
RAX: dffffc0000000004 RBX: ffff88802b765a00 RCX: ffffffff821183c6
RDX: ffff88805c7b8000 RSI: ffffffff820c0cb8 RDI: 0000000000000005
RBP: ffff8880341fb780 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000fffffff4 R11: 0000000000000001 R12: 0000000000002000
R13: 1ffff9200073bfaa R14: 0000200000ffc000 R15: ffff88802b765b70
FS:  00005555814db380(0000) GS:ffff8881249b8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff0b8728e0 CR3: 000000007802e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f46ffb182e9
Code: 48 83 c4 28 c3 e8 17 1a 00 00 0f 1f 80 00 00 00 00 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:00007fff0b8738c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
RAX: ffffffffffffffda RBX: 00007fff0b8738d0 RCX: 00007f46ffb182e9
RDX: 0000000000003000 RSI: 0000000000001000 RDI: 0000200000ffc000
RBP: 0000000000000001 R08: 0000200000ffa000 R09: 00007f46ffb80031
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f46ffb83618
R13: 00007fff0b873aa8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vrm_uncharge mm/mremap.c:964 [inline]
RIP: 0010:expand_vma_in_place mm/mremap.c:1566 [inline]
RIP: 0010:expand_vma mm/mremap.c:1621 [inline]
RIP: 0010:mremap_at mm/mremap.c:1682 [inline]
RIP: 0010:do_mremap mm/mremap.c:1727 [inline]
RIP: 0010:__do_sys_mremap+0x1392/0x15c0 mm/mremap.c:1784
Code: 0f 85 45 02 00 00 48 8b 04 24 c6 84 24 70 01 00 00 01 48 01 85 68 02 00 00 eb 9a e8 18 34 af ff 48 b8 04 00 00 00 00 fc ff df <80> 38 00 0f 85 a7 01 00 00 48 8b 2c 25 20 00 00 00 31 ff 81 e5 00
RSP: 0018:ffffc900039dfd20 EFLAGS: 00010293
RAX: dffffc0000000004 RBX: ffff88802b765a00 RCX: ffffffff821183c6
RDX: ffff88805c7b8000 RSI: ffffffff820c0cb8 RDI: 0000000000000005
RBP: ffff8880341fb780 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000fffffff4 R11: 0000000000000001 R12: 0000000000002000
R13: 1ffff9200073bfaa R14: 0000200000ffc000 R15: ffff88802b765b70
FS:  00005555814db380(0000) GS:ffff8881249b8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff0b8728e0 CR3: 000000007802e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	48 83 c4 28          	add    $0x28,%rsp
   4:	c3                   	ret
   5:	e8 17 1a 00 00       	call   0x1a21
   a:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  11:	48 89 f8             	mov    %rdi,%rax
  14:	48 89 f7             	mov    %rsi,%rdi
  17:	48 89 d6             	mov    %rdx,%rsi
  1a:	48 89 ca             	mov    %rcx,%rdx
  1d:	4d 89 c2             	mov    %r8,%r10
  20:	4d 89 c8             	mov    %r9,%r8
  23:	4c 8b 4c 24 08       	mov    0x8(%rsp),%r9
  28:	0f 05                	syscall
* 2a:	48 3d 01 f0 ff ff    	cmp    $0xfffffffffffff001,%rax <-- trapping instruction
  30:	73 01                	jae    0x33
  32:	c3                   	ret
  33:	48 c7 c1 b8 ff ff ff 	mov    $0xffffffffffffffb8,%rcx
  3a:	f7 d8                	neg    %eax
  3c:	64 89 01             	mov    %eax,%fs:(%rcx)
  3f:	48                   	rex.W


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