CVE-2022-50578

Summary

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

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/4efa5443817c1b6de22d401aeca5b2481e835f8c
• https://git.kernel.org/stable/c/3bb9c92c27624ad076419a70f2b1a30cd1f8bbbd
• https://git.kernel.org/stable/c/3e0efc3f3f5e5c73996782f8db69963e501bb878
• https://git.kernel.org/stable/c/18a7200646958cf8e1b8a933de08122fc50676cd
• https://git.kernel.org/stable/c/417ef049e3fd3b0d2593c1d5ffa3d0d5d0a018a7
• https://git.kernel.org/stable/c/e764ad5918a099ebeb909ccff83893a714e497e1
• https://git.kernel.org/stable/c/abaedb68a769e6bf36836b55a2f49b531c5f3f7b
• https://git.kernel.org/stable/c/8c3e8a6bdb5253b97ad532570f8b5db5f7a06407

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