CVE-2022-50578
Description
In the Linux kernel, the following vulnerability has been resolved:
class: fix possible memory leak in __class_register()
If class_add_groups() returns error, the 'cp->subsys' need be unregister, and the 'cp' need be freed.
We can not call kset_unregister() here, because the 'cls' will be freed in callback function class_release() and it's also freed in caller's error path, it will cause double free.
So fix this by calling kobject_del() and kfree_const(name) to cleanup kobject. Besides, call kfree() to free the 'cp'.
Fault injection test can trigger this:
unreferenced object 0xffff888102fa8190 (size 8): comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s) hex dump (first 8 bytes): 70 6b 74 63 64 76 64 00 pktcdvd. backtrace: [<00000000e7c7703d>] __kmalloc_track_caller+0x1ae/0x320 [<000000005e4d70bc>] kstrdup+0x3a/0x70 [<00000000c2e5e85a>] kstrdup_const+0x68/0x80 [<000000000049a8c7>] kvasprintf_const+0x10b/0x190 [<0000000029123163>] kobject_set_name_vargs+0x56/0x150 [<00000000747219c9>] kobject_set_name+0xab/0xe0 [<0000000005f1ea4e>] __class_register+0x15c/0x49a
unreferenced object 0xffff888037274000 (size 1024): comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s) hex dump (first 32 bytes): 00 40 27 37 80 88 ff ff 00 40 27 37 80 88 ff ff .@'7.....@'7.... 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... backtrace: [<00000000151f9600>] kmem_cache_alloc_trace+0x17c/0x2f0 [<00000000ecf3dd95>] __class_register+0x86/0x49a
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A memory leak in Linux kernel's __class_register() occurs when class_add_groups() fails, leaving allocated kobject and class private data unfreed.
Vulnerability
Overview
In the Linux kernel, the __class_register() function allocates a class_private structure (cp) and a kobject name, then attempts to add attribute groups via class_add_groups(). If class_add_groups() fails, the error path does not properly clean up the cp->subsys kobject or free the cp structure, leading to a memory leak [1][2][3]. The kernel's fault injection testing confirmed this leak, showing unreferenced objects of sizes 8 and 1024 bytes.
Exploitation
Prerequisites
This vulnerability is triggered during module loading when a class registration fails due to an error in adding sysfs attribute groups. An attacker would need the ability to load a kernel module that registers a class and causes class_add_groups() to fail—typically requiring local access or the ability to trigger a specific error condition. No special privileges beyond module loading capability are required.
Impact
A local attacker (or a system administrator) could repeatedly trigger this error path to exhaust kernel memory, potentially leading to a denial-of-service (DoS) condition. The leak is small per occurrence but can accumulate over time.
Mitigation
The fix was applied in the Linux kernel stable tree, backported to multiple stable releases [1][2][3]. Users should update to a kernel version containing the commit that replaces the incomplete cleanup with kobject_del(), kfree_const(name), and kfree(cp) to properly release all resources.
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1Patches
84efa5443817c3bb9c92c27623e0efc3f3f5e18a720064695417ef049e3fde764ad5918a0abaedb68a7698c3e8a6bdb52Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
8- git.kernel.org/stable/c/18a7200646958cf8e1b8a933de08122fc50676cdnvd
- git.kernel.org/stable/c/3bb9c92c27624ad076419a70f2b1a30cd1f8bbbdnvd
- git.kernel.org/stable/c/3e0efc3f3f5e5c73996782f8db69963e501bb878nvd
- git.kernel.org/stable/c/417ef049e3fd3b0d2593c1d5ffa3d0d5d0a018a7nvd
- git.kernel.org/stable/c/4efa5443817c1b6de22d401aeca5b2481e835f8cnvd
- git.kernel.org/stable/c/8c3e8a6bdb5253b97ad532570f8b5db5f7a06407nvd
- git.kernel.org/stable/c/abaedb68a769e6bf36836b55a2f49b531c5f3f7bnvd
- git.kernel.org/stable/c/e764ad5918a099ebeb909ccff83893a714e497e1nvd
News mentions
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