CVE-2026-64599 in Linux
Summary
by MITRE • 08/06/2026
In the Linux kernel, the following vulnerability has been resolved:
crypto: amlogic - avoid double cleanup in meson_crypto_probe()
When meson_allocate_chanlist() fails after a partial allocation, it already unwinds the allocated chanlist state through its local error path. meson_crypto_probe() then jump to error_flow and calls meson_free_chanlist() again, causing the same per-flow resources to be torn down twice. In the reproduced failure path, the second teardown re-entered crypto_engine_exit() on an already destroyed worker and KASAN reported a slab-use-after-free in kthread_destroy_worker().
Prevent double-free by handling partial allocation failures locally within meson_allocate_chanlist() and skipping the outer cleanup path.
The bug was first flagged by an experimental analysis tool we are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under development and is not yet publicly available.
The bug was reproduced in a QEMU x86_64 guest booted with KASAN on v7.1, using the reproducer under tools/testing/meson_crypto_probe. The reproducer forces the second dma_alloc_attrs() call in the gxl-crypto probe path to return NULL, making meson_allocate_chanlist() fail after partial initialization. On the unpatched kernel this reliably triggered a slab-use-after-free. With this fix applied, the same reproducer no longer emits any KASAN report and the probe fails cleanly with -ENOMEM.
================================================================== BUG: KASAN: slab-use-after-free in kthread_destroy_worker+0xb2/0xd0 Read of size 8 at addr ff1100010c057a68 by task insmod/265
CPU: 1 UID: 0 PID: 265 Comm: insmod Tainted: G O 7.1.0-rc2-00376-g810af9adc907-dirty #10 PREEMPT(lazy) Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x68/0xa0 print_report+0xcb/0x5e0 ? __virt_addr_valid+0x21d/0x3f0 ? kthread_destroy_worker+0xb2/0xd0 ? kthread_destroy_worker+0xb2/0xd0 kasan_report+0xca/0x100 ? kthread_destroy_worker+0xb2/0xd0 kthread_destroy_worker+0xb2/0xd0 meson_crypto_probe+0x4d0/0xc10 [amlogic_gxl_crypto]
platform_probe+0x99/0x140 really_probe+0x1c6/0x6a0 ? __pfx___device_attach_driver+0x10/0x10 __driver_probe_device+0x248/0x310 ? acpi_driver_match_device+0xb0/0x100 driver_probe_device+0x48/0x210 ? __pfx___device_attach_driver+0x10/0x10 __device_attach_driver+0x160/0x320 bus_for_each_drv+0x104/0x190 ? __pfx_bus_for_each_drv+0x10/0x10 ? _raw_spin_unlock_irqrestore+0x2c/0x50 __device_attach+0x19d/0x3b0 ? __pfx___device_attach+0x10/0x10 ? do_raw_spin_unlock+0x53/0x220 device_initial_probe+0x78/0xa0 bus_probe_device+0x5b/0x130 device_add+0xcfd/0x1430 ? __pfx_device_add+0x10/0x10 ? insert_resource+0x34/0x50 ? lock_release+0xc9/0x290 platform_device_add+0x24e/0x590 ? __pfx_meson_crypto_probe_repro_init+0x10/0x10 [meson_crypto_probe_repro]
meson_crypto_probe_repro_init+0x330/0xff0 [meson_crypto_probe_repro]
do_one_initcall+0xc0/0x450 ? __pfx_do_one_initcall+0x10/0x10 ? _raw_spin_unlock_irqrestore+0x2c/0x50 ? __create_object+0x59/0x80 ? kasan_unpoison+0x27/0x60 do_init_module+0x27b/0x7d0 ? __pfx_do_init_module+0x10/0x10 ? kasan_quarantine_put+0x84/0x1d0 ? kfree+0x32c/0x510 ? load_module+0x561e/0x5ff0 load_module+0x54fe/0x5ff0 ? __pfx_load_module+0x10/0x10 ? security_file_permission+0x20/0x40 ? kernel_read_file+0x23d/0x6e0 ? mmap_region+0x235/0x4a0 ? __pfx_kernel_read_file+0x10/0x10 ? __file_has_perm+0x2c0/0x3e0 init_module_from_file+0x158/0x180 ? __pfx_init_module_from_file+0x10/0x10 ? __lock_acquire+0x45a/0x1ba0 ? idempotent_init_module+0x315/0x610 ? lock_release+0xc9/0x290 ? lock ---truncated---
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Analysis
by VulDB Data Team • 08/06/2026
The vulnerability in question resides within the amlogic crypto driver of the Linux kernel, specifically affecting the meson_crypto_probe() function. This flaw manifests as a double cleanup scenario that leads to a slab-use-after-free condition under certain error conditions. The root cause lies in how memory allocation failures are handled during the probe process, particularly when partial allocation has already occurred but the outer error path is subsequently invoked, resulting in redundant resource deallocation. The issue was identified through an internal kernel memory management analysis tool designed to detect such subtle memory corruption patterns, highlighting a critical gap in proper error handling for partial state initialization.
The technical execution of this vulnerability begins with meson_allocate_chanlist() function which performs allocations for channel lists and handles cleanup internally upon failure. However, when this function encounters an error after partial allocation, it correctly unwinds its own allocated state but does not prevent the calling context from proceeding to error_flow where meson_free_chanlist() is invoked again. This results in a second teardown of already destroyed resources, particularly targeting crypto_engine_exit() and kthread_destroy_worker functions that are called on an already compromised worker context. The KASAN (Kernel Address Sanitizer) detection mechanism flags this pattern as a slab-use-after-free error, indicating memory corruption where freed kernel objects are accessed again.
The operational impact of this vulnerability extends beyond simple kernel crashes, presenting potential security implications through memory corruption that could be exploited by malicious actors to gain unauthorized access or escalate privileges. The flaw particularly affects systems utilizing the amlogic gxl crypto driver and manifests during module loading when specific allocation failures occur. This aligns with CWE-415: Double Free, a well-known class of vulnerabilities in kernel space where resources are freed twice leading to memory corruption. The issue also relates to ATT&CK technique T1068: Exploitation for Privilege Escalation, as memory corruption vulnerabilities can serve as entry points for privilege escalation attacks.
The fix for this vulnerability involves modifying the error handling path within meson_allocate_chanlist() to prevent the outer cleanup mechanism from executing when partial allocation failures occur. This ensures that resource deallocation happens only once, eliminating the double-free scenario. The patch implements a local handling approach for partial allocation failures rather than allowing them to propagate to the outer error_flow path. Testing with KASAN enabled on kernel version 7.1 confirmed that this fix resolves the reported slab-use-after-free condition, with the reproducer now failing cleanly with -ENOMEM instead of triggering memory corruption. This solution addresses both the immediate technical flaw and prevents potential exploitation while maintaining the driver's functionality under normal operating conditions.
The vulnerability analysis demonstrates the importance of careful resource management in kernel drivers, particularly when dealing with complex allocation scenarios involving multiple subsystems such as DMA memory allocation and crypto engine initialization. The issue highlights how seemingly isolated function failures can cascade into more serious corruption patterns when error handling paths are not carefully designed to prevent redundant operations. This case study reinforces the necessity of thorough testing methodologies including KASAN and other memory debugging tools in kernel development processes, especially for device drivers that manage complex hardware interfaces and resource allocation sequences. The fix represents a defensive programming approach that prevents state inconsistencies by ensuring proper isolation between different error handling paths in the driver's initialization sequence.
The resolution methodology implemented follows established best practices for kernel memory safety, where the solution focuses on preventing the specific double cleanup scenario rather than attempting to patch the underlying subsystems. This targeted approach minimizes the risk of introducing regressions while effectively addressing the root cause. The vulnerability serves as a reminder that even in well-established kernel subsystems, subtle race conditions and error path interactions can create serious security implications. The fact that this issue was detected through an experimental analysis tool suggests that such automated static analysis methods will become increasingly important for identifying complex memory management issues in large codebases like the Linux kernel.