CVE-2025-38320 in Linux
Summary
by MITRE • 07/10/2025
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()]
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Analysis
by VulDB Data Team • 12/19/2025
The vulnerability CVE-2025-38320 affects the Linux kernel's arm64 architecture and is classified as a stack-out-of-bounds read in the function regs_get_kernel_stack_nth(). This issue was identified through KASAN (Kernel Address Sanitizer) which detected an invalid memory access pattern during kernel execution. The flaw manifests when the kernel attempts to read from a memory location that lies outside the valid stack bounds of the calling task, triggering a KASAN report and potentially leading to system instability or exploitation. The vulnerability occurs within the ptrace subsystem, a mechanism used for debugging and process tracing in Linux systems.
The technical root cause lies in how the regs_get_kernel_stack_nth() function handles stack pointer dereferencing without proper bounds checking. According to the call trace, the error originates from a read operation of size 8 at address ffff800089277c10, which is part of the stack frame for task 1.sh. The KASAN report indicates that while the address is determined to belong to the stack of the current task, the access pattern triggers a false positive detection due to compiler optimizations or memory layout assumptions. This type of vulnerability is particularly concerning because it involves kernel-level memory management and can be exploited to bypass security controls or cause denial of service conditions.
The operational impact of this vulnerability extends beyond simple memory corruption, as it affects the core debugging and tracing capabilities of the Linux kernel. When exploited, the stack-out-of-bounds read could allow malicious actors to gain unauthorized access to kernel memory regions, potentially leading to privilege escalation or information disclosure. The issue is particularly relevant in environments where ptrace operations are frequently used, such as in debugging tools, containerization systems, or security monitoring applications. The vulnerability aligns with CWE-129, which describes improper validation of array indices, and can be mapped to ATT&CK technique T1059.001 for execution through system commands and T1068 for local privilege escalation.
The fix implemented for this vulnerability follows a well-established pattern used previously on the s390 architecture, utilizing the READ_ONCE_NOCHECK() helper macro to suppress KASAN false positives. This approach acknowledges that while the address appears to be on the stack, the compiler's optimization may cause KASAN to incorrectly flag the access as invalid. By using READ_ONCE_NOCHECK(), the kernel can safely read from the memory location without triggering false positives while maintaining the semantic correctness of the operation. This solution reflects the broader challenge in kernel security where compiler optimizations can create false positives in static analysis tools, requiring careful balancing between security detection and system functionality. The mitigation strategy ensures that legitimate kernel operations are not blocked by overly aggressive memory checking mechanisms while maintaining overall system security posture.