CVE-2025-38320 arm64/ptrace: Fix stack-out-of-bounds read in regs_get_kernel_stack_nth()
A stack-out-of-bounds read in the Linux kernel's arm64 ptrace implementation allows attackers to potentially disclose memory or cause a system crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38320?
CVE-2025-38320 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 10 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
arm64/ptrace: Fix stack-out-of-bounds read in regs_get_kernel_stack_nth()
KASAN reports a stack-out-of-bounds read in regs_get_kernel_stack_nth().
Call Trace: [ 97.283505] BUG: KASAN: stack-out-of-bounds in regs_get_kernel_stack_nth+0xa8/0xc8 [ 97.284677] Read of size 8 at addr ffff800089277c10 by task 1.sh/2550 [ 97.285732] [ 97.286067] CPU: 7 PID: 2550 Comm: 1.sh Not tainted 6.6.0+ #11 [ 97.287032] Hardware name: linux,dummy-virt (DT) [ 97.287815] Call trace: [ 97.288279] dump_backtrace+0xa0/0x128 [ 97.288946] show_stack+0x20/0x38 [ 97.289551] dump_stack_lvl+0x78/0xc8 [ 97.290203] print_address_description.constprop.0+0x84/0x3c8 [ 97.291159] print_report+0xb0/0x280 [ 97.291792] kasan_report+0x84/0xd0 [ 97.292421] __asan_load8+0x9c/0xc0 [ 97.293042] regs_get_kernel_stack_nth+0xa8/0xc8 [ 97.293835] process_fetch_insn+0x770/0xa30 [ 97.294562] kprobe_trace_func+0x254/0x3b0 [ 97.295271] kprobe_dispatcher+0x98/0xe0 [ 97.295955] kprobe_breakpoint_handler+0x1b0/0x210 [ 97.296774] call_break_hook+0xc4/0x100 [ 97.297451] brk_handler+0x24/0x78 [ 97.298073] do_debug_exception+0xac/0x178 [ 97.298785] el1_dbg+0x70/0x90 [ 97.299344] el1h_64_sync_handler+0xcc/0xe8 [ 97.300066] el1h_64_sync+0x78/0x80 [ 97.300699] kernel_clone+0x0/0x500 [ 97.301331] __arm64_sys_clone+0x70/0x90 [ 97.302084] invoke_syscall+0x68/0x198 [ 97.302746] el0_svc_common.constprop.0+0x11c/0x150 [ 97.303569] do_el0_svc+0x38/0x50 [ 97.304164] el0_svc+0x44/0x1d8 [ 97.304749] el0t_64_sync_handler+0x100/0x130 [ 97.305500] el0t_64_sync+0x188/0x190 [ 97.306151] [ 97.306475] The buggy address belongs to stack of task 1.sh/2550 [ 97.307461] and is located at offset 0 in frame: [ 97.308257] __se_sys_clone+0x0/0x138 [ 97.308910] [ 97.309241] This frame has 1 object: [ 97.309873] [48, 184) 'args' [ 97.309876] [ 97.310749] The buggy address belongs to the virtual mapping at [ 97.310749] [ffff800089270000, ffff800089279000) created by: [ 97.310749] dup_task_struct+0xc0/0x2e8 [ 97.313347] [ 97.313674] The buggy address belongs to the physical page: [ 97.314604] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14f69a [ 97.315885] flags: 0x15ffffe00000000(node=1|zone=2|lastcpupid=0xfffff) [ 97.316957] raw: 015ffffe00000000 0000000000000000 dead000000000122 0000000000000000 [ 97.318207] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 [ 97.319445] page dumped because: kasan: bad access detected [ 97.320371] [ 97.320694] Memory state around the buggy address: [ 97.321511] ffff800089277b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 97.322681] ffff800089277b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 97.323846] >ffff800089277c00: 00 00 f1 f1 f1 f1 f1 f1 00 00 00 00 00 00 00 00 [ 97.325023] ^ [ 97.325683] ffff800089277c80: 00 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3 f3 f3 [ 97.326856] ffff800089277d00: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
This issue seems to be related to the behavior of some gcc compilers and was also fixed on the s390 architecture before:
commit d93a855c31b7 ("s390/ptrace: Avoid KASAN false positives in regs_get_kernel_stack_nth()")
As described in that commit, regs_get_kernel_stack_nth() has confirmed that `addr` is on the stack, so reading the value at `*addr` should be allowed. Use READ_ONCE_NOCHECK() helper to silence the KASAN check for this case.
[will: Use '*addr' as the argument to READ_ONCE_NOCHECK()]
Weakness: CWE-125
Which versions are affected by CVE-2025-38320?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38320?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-38320 being exploited?
There is no known exploitation of CVE-2025-38320 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64916, BELL-CVE-2025-38320, DEBIAN-CVE-2025-38320, GHSA-784p-42hr-j7xp, ROOT-OS-DEBIAN-11-CVE-2025-38320, ROOT-OS-DEBIAN-12-CVE-2025-38320 and 3 more.