CVE-2023-52560: Vulnerability in Linux Linux

Severity: lowType: vulnerabilityCVE-2023-52560

In the Linux kernel, the following vulnerability has been resolved: mm/damon/vaddr-test: fix memory leak in damon_do_test_apply_three_regions() When CONFIG_DAMON_VADDR_KUNIT_TEST=y and making CONFIG_DEBUG_KMEMLEAK=y and CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN=y, the below memory leak is detected. Since commit 9f86d624292c ("mm/damon/vaddr-test: remove unnecessary variables"), the damon_destroy_ctx() is removed, but still call damon_new_target() and damon_new_region(), the damon_region which is allocated by kmem_cache_alloc() in damon_new_region() and the damon_target which is allocated by kmalloc in damon_new_target() are not freed. And the damon_region which is allocated in damon_new_region() in damon_set_regions() is also not freed. So use damon_destroy_target to free all the damon_regions and damon_target. unreferenced object 0xffff888107c9a940 (size 64): comm "kunit_try_catch", pid 1069, jiffies 4294670592 (age 732.761s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 06 00 00 00 6b 6b 6b 6b ............kkkk 60 c7 9c 07 81 88 ff ff f8 cb 9c 07 81 88 ff ff `............... backtrace: [<ffffffff817e0167>] kmalloc_trace+0x27/0xa0 [<ffffffff819c11cf>] damon_new_target+0x3f/0x1b0 [<ffffffff819c7d55>] damon_do_test_apply_three_regions.constprop.0+0x95/0x3e0 [<ffffffff819c82be>] damon_test_apply_three_regions1+0x21e/0x260 [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90 [<ffffffff81237cf6>] kthread+0x2b6/0x380 [<ffffffff81097add>] ret_from_fork+0x2d/0x70 [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20 unreferenced object 0xffff8881079cc740 (size 56): comm "kunit_try_catch", pid 1069, jiffies 4294670592 (age 732.761s) hex dump (first 32 bytes): 05 00 00 00 00 00 00 00 14 00 00 00 00 00 00 00 ................ 6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b kkkkkkkk....kkkk backtrace: [<ffffffff819bc492>] damon_new_region+0x22/0x1c0 [<ffffffff819c7d91>] damon_do_test_apply_three_regions.constprop.0+0xd1/0x3e0 [<ffffffff819c82be>] damon_test_apply_three_regions1+0x21e/0x260 [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90 [<ffffffff81237cf6>] kthread+0x2b6/0x380 [<ffffffff81097add>] ret_from_fork+0x2d/0x70 [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20 unreferenced object 0xffff888107c9ac40 (size 64): comm "kunit_try_catch", pid 1071, jiffies 4294670595 (age 732.843s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 06 00 00 00 6b 6b 6b 6b ............kkkk a0 cc 9c 07 81 88 ff ff 78 a1 76 07 81 88 ff ff ........x.v..... backtrace: [<ffffffff817e0167>] kmalloc_trace+0x27/0xa0 [<ffffffff819c11cf>] damon_new_target+0x3f/0x1b0 [<ffffffff819c7d55>] damon_do_test_apply_three_regions.constprop.0+0x95/0x3e0 [<ffffffff819c851e>] damon_test_apply_three_regions2+0x21e/0x260 [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90 [<ffffffff81237cf6>] kthread+0x2b6/0x380 [<ffffffff81097add>] ret_from_fork+0x2d/0x70 [<ffffffff81003791>] ret_from_fork_asm+0x11/0x20 unreferenced object 0xffff8881079ccc80 (size 56): comm "kunit_try_catch", pid 1071, jiffies 4294670595 (age 732.843s) hex dump (first 32 bytes): 05 00 00 00 00 00 00 00 14 00 00 00 00 00 00 00 ................ 6b 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 6b 6b 6b 6b kkkkkkkk....kkkk backtrace: [<ffffffff819bc492>] damon_new_region+0x22/0x1c0 [<ffffffff819c7d91>] damon_do_test_apply_three_regions.constprop.0+0xd1/0x3e0 [<ffffffff819c851e>] damon_test_apply_three_regions2+0x21e/0x260 [<ffffffff829fce6a>] kunit_generic_run_threadfn_adapter+0x4a/0x90 [<ffffffff81237cf6>] kthread+0x2b6/0x380 [<ffffffff81097add>] ret_from_fork+0x2d/0x70 [<ffff ---truncated---

AI Analysis

Technical Summary

CVE-2023-52560 addresses a memory leak vulnerability in the Linux kernel specifically within the DAMON (Data Access Monitor) subsystem's unit testing code. The issue arises when certain kernel configuration options are enabled: CONFIG_DAMON_VADDR_KUNIT_TEST=y, CONFIG_DEBUG_KMEMLEAK=y, and CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN=y. The vulnerability is due to improper memory management after a code refactor where the damon_destroy_ctx() function was removed but calls to damon_new_target() and damon_new_region() remained. These functions allocate memory for damon_target and damon_region objects using kmalloc and kmem_cache_alloc, but the allocated memory is not freed, resulting in a memory leak. The leak manifests during the execution of the damon_do_test_apply_three_regions() function and its related test functions, which are part of the kernel's internal testing framework (kunit). The unreferenced objects are detected by the kernel's memory leak detection mechanisms, with backtraces indicating the allocation points. This vulnerability is confined to the kernel's testing code and requires specific debug configurations to be enabled. It does not affect the normal operation of the Linux kernel in production environments where these debug/testing options are not enabled. There is no evidence of exploitation in the wild, and the issue was resolved by reintroducing proper cleanup via damon_destroy_target() to free all allocated damon_regions and damon_targets. No CVSS score has been assigned to this vulnerability.

Potential Impact

For European organizations, the practical impact of CVE-2023-52560 is minimal under standard operational conditions. Since the vulnerability exists only when specific kernel debug and testing configurations are enabled, it is unlikely to affect production systems. The memory leak could lead to increased memory consumption and potential resource exhaustion if the affected test code is run repeatedly in a debug environment, possibly impacting kernel stability during testing or development. However, this does not translate into a direct security compromise such as privilege escalation, remote code execution, or data leakage. Organizations running custom Linux kernels with these debug options enabled for development or testing purposes should be aware of this issue to avoid misleading memory leak reports or resource wastage. In production environments, the vulnerability poses negligible risk. Therefore, the threat to confidentiality, integrity, and availability of systems in European enterprises is very low. Nonetheless, organizations with critical infrastructure or embedded systems that might enable such debug features for diagnostics should verify their kernel configurations to prevent unintended resource leaks.

Mitigation Recommendations

1. Ensure that production Linux kernels deployed in European organizations do not enable CONFIG_DAMON_VADDR_KUNIT_TEST, CONFIG_DEBUG_KMEMLEAK, or CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN unless explicitly required for debugging or testing purposes. 2. For development and testing environments where these options are necessary, update the Linux kernel to a version that includes the fix for CVE-2023-52560, which properly frees allocated memory in the DAMON test code. 3. Regularly monitor kernel memory usage and run memory leak detection tools to identify and address any abnormal memory consumption during testing. 4. Implement strict kernel configuration management policies to prevent debug/testing options from being enabled inadvertently in production systems. 5. Maintain an up-to-date patch management process to apply Linux kernel updates promptly, especially those addressing memory management and stability issues. 6. Educate development and operations teams about the scope and impact of this vulnerability to avoid unnecessary concern or misinterpretation of memory leak reports during kernel testing.