[Android 6.1] BUG: unable to handle kernel paging request in ext4_free_ext_path

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8852ea8c096a UPSTREAM: tipc: fix double-free in tipc_buf_a..
git tree: android14-6.1
console output: https://syzkaller.appspot.com/x/log.txt?x=10f982ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8b77de3a119dd560
dashboard link: https://syzkaller.appspot.com/bug?extid=0834b0436c539d14fbb5
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e462ce580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11347236580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/91f8d7aaf74f/disk-8852ea8c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0f5a22c83c0c/vmlinux-8852ea8c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/30d4cfb8b544/bzImage-8852ea8c.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b328ef1c356e/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=126db2d2580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0834b0...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 128
EXT4-fs (loop2): mounted filesystem without journal. Quota mode: none.
ext4 filesystem being mounted at /0/file0aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa supports timestamps until 2038-01-19 (0x7fffffff)
BUG: unable to handle page fault for address: ffffffffffffffec
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 7012067 P4D 7012067 PUD 7014067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 363 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline]
RIP: 0010:ext4_free_ext_path+0x44/0x120 fs/ext4/extents.c:128
Code: 85 db 0f 84 ba 00 00 00 49 bf 00 00 00 00 00 fc ff df 48 8d 7b 08 48 89 f8 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 b4 00 00 00 <0f> b7 43 08 c1 e0 04 48 8d 04 40 48 89 45 c0 48 89 5d d0 48 8d 43
RSP: 0018:ffffc900007b75b0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffffffffffe4 RCX: ffff888113b7a880
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffffffffffec
RBP: ffffc900007b75f0 R08: ffff8881241fc017 R09: 1ffff1102483f802
R10: dffffc0000000000 R11: ffffed102483f803 R12: ffff8881241fc050
R13: ffffffffffffffe4 R14: dffffc0000000000 R15: dffffc0000000000
FS: 0000555566a02500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffec CR3: 000000012db00000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
finish_range+0x22d/0x340 fs/ext4/migrate.c:60
update_extent_range fs/ext4/migrate.c:83 [inline]
update_ind_extent_range+0x30d/0x530 fs/ext4/migrate.c:106
update_dind_extent_range+0x146/0x210 fs/ext4/migrate.c:135
ext4_ext_migrate+0xa57/0xe60 fs/ext4/migrate.c:529
__ext4_ioctl fs/ext4/ioctl.c:1399 [inline]
ext4_ioctl+0x1e4f/0x3ee0 fs/ext4/ioctl.c:1617
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0x12f/0x1b0 fs/ioctl.c:856
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:856
x64_sys_call+0x58b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f544e59cdd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd3cd55eb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f544e815fa0 RCX: 00007f544e59cdd9
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007f544e632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f544e815fac R14: 00007f544e815fa0 R15: 00007f544e815fa0
</TASK>
Modules linked in:
CR2: ffffffffffffffec
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline]
RIP: 0010:ext4_free_ext_path+0x44/0x120 fs/ext4/extents.c:128
Code: 85 db 0f 84 ba 00 00 00 49 bf 00 00 00 00 00 fc ff df 48 8d 7b 08 48 89 f8 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 b4 00 00 00 <0f> b7 43 08 c1 e0 04 48 8d 04 40 48 89 45 c0 48 89 5d d0 48 8d 43
RSP: 0018:ffffc900007b75b0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffffffffffe4 RCX: ffff888113b7a880
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffffffffffec
RBP: ffffc900007b75f0 R08: ffff8881241fc017 R09: 1ffff1102483f802
R10: dffffc0000000000 R11: ffffed102483f803 R12: ffff8881241fc050
R13: ffffffffffffffe4 R14: dffffc0000000000 R15: dffffc0000000000
FS: 0000555566a02500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffec CR3: 000000012db00000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 85 db test %ebx,%ebx
2: 0f 84 ba 00 00 00 je 0xc2
8: 49 bf 00 00 00 00 00 movabs $0xdffffc0000000000,%r15
f: fc ff df
12: 48 8d 7b 08 lea 0x8(%rbx),%rdi
16: 48 89 f8 mov %rdi,%rax
19: 48 c1 e8 03 shr $0x3,%rax
1d: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax
22: 84 c0 test %al,%al
24: 0f 85 b4 00 00 00 jne 0xde
* 2a: 0f b7 43 08 movzwl 0x8(%rbx),%eax <-- trapping instruction
2e: c1 e0 04 shl $0x4,%eax
31: 48 8d 04 40 lea (%rax,%rax,2),%rax
35: 48 89 45 c0 mov %rax,-0x40(%rbp)
39: 48 89 5d d0 mov %rbx,-0x30(%rbp)
3d: 48 rex.W
3e: 8d .byte 0x8d
3f: 43 rex.XB


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