syzbot

rust_kernel: panicked at drivers/staging/android/ashmem_rust.rs:418:13:
attempt to subtract with overflow
------------[ cut here ]------------
kernel BUG at rust/helpers/bug.c:7!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 297 Comm: syz-executor294 Not tainted 6.12.30-syzkaller-g1d4f4d446dbd #0 c93aecf919cd453af8c9b0d1ce6d9747cbb4dbdf
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:rust_helper_BUG+0x8/0x10 rust/helpers/bug.c:7
Code: ce 82 e7 02 cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 b8 91 8b 25 99 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 e5 <0f> 0b 66 0f 1f 44 00 00 b8 db 4f 6c 15 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000128f670 EFLAGS: 00010246
RAX: 0000000000000069 RBX: 1ffff92000251ed0 RCX: c16663796012e500
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffffc9000128f670 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000251e34 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffc9000128f6a0 R15: ffffc9000128f6d0
FS:  0000555577db5480(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002600 CR3: 00000001027c2000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __rustc::rust_begin_unwind+0x15b/0x160 rust/kernel/lib.rs:128
 core::panicking::panic_fmt+0x84/0x90 usr/local/rustup/toolchains/1.87.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panicking.rs:75
 core::panicking::panic_const::panic_const_sub_overflow+0xb2/0xc0 usr/local/rustup/toolchains/1.87.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panicking.rs:178
 <ashmem_rust::Ashmem>::pin_unpin drivers/staging/android/ashmem_rust.rs:418 [inline]
 <ashmem_rust::Ashmem as kernel::miscdevice::MiscDevice>::ioctl+0x2c01/0x2ed0 drivers/staging/android/ashmem_rust.rs:256
 kernel::miscdevice::fops_ioctl::<ashmem_rust::Ashmem>+0x99/0x110 rust/kernel/miscdevice.rs:485
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x135/0x1b0 fs/ioctl.c:893
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:893
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f62f774c139
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffceac70c18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f62f779515d RCX: 00007f62f774c139
RDX: 0000200000002600 RSI: 0000000040087708 RDI: 0000000000000003
RBP: 00007f62f779512d R08: 00007f62f779512d R09: 00007f62f779a4bc
R10: 00007ffceac70c20 R11: 0000000000000246 R12: 00007f62f779a4bc
R13: 00007f62f7795095 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rust_helper_BUG+0x8/0x10 rust/helpers/bug.c:7
Code: ce 82 e7 02 cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 b8 91 8b 25 99 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 e5 <0f> 0b 66 0f 1f 44 00 00 b8 db 4f 6c 15 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000128f670 EFLAGS: 00010246
RAX: 0000000000000069 RBX: 1ffff92000251ed0 RCX: c16663796012e500
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffffc9000128f670 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000251e34 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffc9000128f6a0 R15: ffffc9000128f6d0
FS:  0000555577db5480(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f2fae86388 CR3: 00000001027c2000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400