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KASAN: null-ptr-deref Write in sys_io_uring_register

Status: upstream: reported C repro on 2024/12/04 13:56
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+092bbab7da235a02a03a@syzkaller.appspotmail.com
Fix commit: xarray-extract-helper-from-__xa_insertcmpxchg-fix
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 532d, last: 525d
Cause bisection: introduced by (bisect log) :
commit d2e88c71bdb07f1e5ccffbcc80d747ccd6144b75
Author: Tamir Duberstein <tamird@gmail.com>
Date: Tue Nov 12 19:25:37 2024 +0000

  xarray: extract helper from __xa_{insert,cmpxchg}

Crash: KASAN: null-ptr-deref Write in sys_io_uring_register (log)
Repro: C syz .config
  
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ID Workflow Result Correct Bug Created Started Finished Revision Error
871fcc57-d289-426d-b506-044c387818ba assessment-security 💥 KASAN: null-ptr-deref Write in sys_io_uring_register 2026/05/17 11:26 2026/05/17 11:26 2026/05/17 11:45 de5aae85e5f28e2fa1c7deefcc24fe286abe5140 failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/8f46b441684a6784b1f8673a31fe69f174b347f2" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General architecture-dependent options * Kprobes (KPROBES) [N/y/?] n Optimize very unlikely/likely branches (JUMP_LABEL) [Y/n/?] y Static key selftest (STATIC_KEYS_SELFTEST) [N/y/?] n Static call selftest (STATIC_CALL_SELFTEST) [N/y/?] n Enable seccomp to safely execute untrusted bytecode (SECCOMP) [Y/n/?] y Show seccomp filter cache status in /proc/pid/seccomp_cache (SECCOMP_CACHE_DEBUG) [N/y/?] n Stack Protector buffer overflow detection (STACKPROTECTOR) [Y/n/?] y Strong Stack Protector (STACKPROTECTOR_STRONG) [Y/n/?] y Link Time Optimization (LTO) > 1. None (LTO_NONE) choice[1]: 1 Enable Clang's AutoFDO build (EXPERIMENTAL) (AUTOFDO_CLANG) [N/y/?] (NEW) Error in reading or end of file. Enable Clang's Propeller build (PROPELLER_CLANG) [N/y/?] (NEW) Error in reading or end of file. Use Clang's Control Flow Integrity (CFI) (CFI_CLANG) [N/y/?] (NEW) Error in reading or end of file. Number of bits to use for ASLR of mmap base address (ARCH_MMAP_RND_BITS) [28] 28 Number of bits to use for ASLR of mmap base address for compatible applications (ARCH_MMAP_RND_COMPAT_BITS) [8] 8 MMU page size > 1. 4KiB pages (PAGE_SIZE_4KB) choice[1]: 1 Provide system calls for 32-bit time_t (COMPAT_32BIT_TIME) [Y/n/?] y Use a virtually-mapped stack (VMAP_STACK) [Y/n/?] y Support for randomizing kernel stack offset on syscall entry (RANDOMIZE_KSTACK_OFFSET) [Y/n/?] y Default state of kernel stack offset randomization (RANDOMIZE_KSTACK_OFFSET_DEFAULT) [N/y/?] n Locking event counts collection (LOCK_EVENT_COUNTS) [N/y/?] n * * Memory initialization * Initialize kernel stack variables at function entry 1. no automatic stack variable initialization (weakest) (INIT_STACK_NONE) 2. pattern-init everything (strongest) (INIT_STACK_ALL_PATTERN) > 3. zero-init everything (strongest and safest) (INIT_STACK_ALL_ZERO) choice[1-3?]: 3 Enable heap memory zeroing on allocation by default (INIT_ON_ALLOC_DEFAULT_ON) [Y/n/?] y Enable heap memory zeroing on free by default (INIT_ON_FREE_DEFAULT_ON) [N/y/?] n Enable register zeroing on function exit (ZERO_CALL_USED_REGS) [N/y/?] (NEW) Error in reading or end of file. * * Kernel hardening options * Randomize layout of sensitive kernel structures > 1. Disable structure layout randomization (RANDSTRUCT_NONE) 2. Fully randomize structure layout (RANDSTRUCT_FULL) (NEW) choice[1-2?]: Error in reading or end of file. * * Compile-time checks and compiler options * Debug information 1. Disable debug information (DEBUG_INFO_NONE) 2. Rely on the toolchain's implicit default DWARF version (DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT) > 3. Generate DWARF Version 4 debuginfo (DEBUG_INFO_DWARF4) 4. Generate DWARF Version 5 debuginfo (DEBUG_INFO_DWARF5) choice[1-4?]: 3 Reduce debugging information (DEBUG_INFO_REDUCED) [N/y/?] n Compressed Debug information > 1. Don't compress debug information (DEBUG_INFO_COMPRESSED_NONE) 2. Compress debugging information with zlib (DEBUG_INFO_COMPRESSED_ZLIB) 3. Compress debugging information with zstd (DEBUG_INFO_COMPRESSED_ZSTD) (NEW) choice[1-3?]: Error in reading or end of file. Produce split debuginfo in .dwo files (DEBUG_INFO_SPLIT) [N/y/?] n Generate BTF type information (DEBUG_INFO_BTF) [N/y/?] n Provide GDB scripts for kernel debugging (GDB_SCRIPTS) [N/y/?] n Warn for stack frames larger than (FRAME_WARN) [2048] 2048 Strip assembler-generated symbols during link (STRIP_ASM_SYMS) [N/y/?] n Install uapi headers to usr/include (HEADERS_INSTALL) [N/y/?] n Make section mismatch errors non-fatal (SECTION_MISMATCH_WARN_ONLY) [Y/n/?] y Force all function address 64B aligned (DEBUG_FORCE_FUNCTION_ALIGN_64B) [N/y/?] n Generate vmlinux.map file when linking (VMLINUX_MAP) [N/y/?] n Force weak per-cpu definitions (DEBUG_FOR
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[syzbot] [io-uring?] KASAN: null-ptr-deref Write in sys_io_uring_register 11 (13) 2024/12/04 20:18

Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_sub_and_test include/linux/atomic/atomic-instrumented.h:4521 [inline]
BUG: KASAN: null-ptr-deref in put_cred_many include/linux/cred.h:255 [inline]
BUG: KASAN: null-ptr-deref in put_cred include/linux/cred.h:269 [inline]
BUG: KASAN: null-ptr-deref in io_unregister_personality io_uring/register.c:82 [inline]
BUG: KASAN: null-ptr-deref in __io_uring_register io_uring/register.c:698 [inline]
BUG: KASAN: null-ptr-deref in __do_sys_io_uring_register io_uring/register.c:902 [inline]
BUG: KASAN: null-ptr-deref in __se_sys_io_uring_register+0x1227/0x3b60 io_uring/register.c:879
Write of size 8 at addr 0000000000000406 by task syz-executor274/5828

CPU: 1 UID: 0 PID: 5828 Comm: syz-executor274 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_report+0xe8/0x550 mm/kasan/report.c:492
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_long_sub_and_test include/linux/atomic/atomic-instrumented.h:4521 [inline]
 put_cred_many include/linux/cred.h:255 [inline]
 put_cred include/linux/cred.h:269 [inline]
 io_unregister_personality io_uring/register.c:82 [inline]
 __io_uring_register io_uring/register.c:698 [inline]
 __do_sys_io_uring_register io_uring/register.c:902 [inline]
 __se_sys_io_uring_register+0x1227/0x3b60 io_uring/register.c:879
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f65bbcb03a9
Code: 48 83 c4 28 c3 e8 37 17 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:00007ffe8fac7478 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 000000000000371d RCX: 00007f65bbcb03a9
RDX: 0000000000000000 RSI: 000000000000000a RDI: 0000000000000003
RBP: 0000000000000003 R08: 00000000000ac5f8 R09: 00000000000ac5f8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe8fac7648 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
==================================================================

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/04 10:08 linux-next c245a7a79602 b50eb251 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/04 09:39 linux-next c245a7a79602 b50eb251 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/04 07:55 linux-next c245a7a79602 b50eb251 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/11 07:06 linux-next af2ea8ab7a54 cfc402b4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/11 07:06 linux-next af2ea8ab7a54 cfc402b4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/09 11:26 linux-next af2ea8ab7a54 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/09 03:36 linux-next af2ea8ab7a54 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/07 10:46 linux-next af2ea8ab7a54 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/07 10:46 linux-next af2ea8ab7a54 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/06 21:31 linux-next af2ea8ab7a54 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/06 21:31 linux-next af2ea8ab7a54 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/04 04:49 linux-next c245a7a79602 b50eb251 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/04 04:25 linux-next c245a7a79602 b50eb251 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/04 01:38 linux-next c245a7a79602 b50eb251 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
2024/12/04 01:37 linux-next c245a7a79602 b50eb251 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: null-ptr-deref Write in sys_io_uring_register
* Struck through repros no longer work on HEAD.