CVE-2022-48988: memcg: fix possible use-after-free in memcg_write_event_control()
First published: Mon Oct 21 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: memcg: fix possible use-after-free in memcg_write_event_control() memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too. Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a call to __file_cft() which verified that the specified file is a regular cgroupfs file before further accesses. The cftype pointer returned from __file_cft() was no longer necessary and the commit inadvertently dropped the file type check with it allowing any file to slip through. With the invarients broken, the d_name and parent accesses can now race against renames and removals of arbitrary files and cause use-after-free's. Fix the bug by resurrecting the file type check in __file_cft(). Now that cgroupfs is implemented through kernfs, checking the file operations needs to go through a layer of indirection. Instead, let's check the superblock and dentry type.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | >=3.14<4.14.302 | |
| Linux Linux kernel | >=4.15<4.19.269 | |
| Linux Linux kernel | >=4.20<5.4.227 | |
| Linux Linux kernel | >=5.5<5.10.159 | |
| Linux Linux kernel | >=5.11<5.15.83 | |
| Linux Linux kernel | >=5.16<6.0.13 | |
| Linux Linux kernel | =6.1-rc1 | |
| Linux Linux kernel | =6.1-rc2 | |
| Linux Linux kernel | =6.1-rc3 | |
| Linux Linux kernel | =6.1-rc4 | |
| Linux Linux kernel | =6.1-rc5 | |
| Linux Linux kernel | =6.1-rc6 | |
| Linux Linux kernel | =6.1-rc7 | |
| Linux Linux kernel | =6.1-rc8 |
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Reference Links
- https://git.kernel.org/stable/c/b77600e26fd48727a95ffd50ba1e937efb548125
- https://git.kernel.org/stable/c/e1ae97624ecf400ea56c238bff23e5cd139df0b8
- https://git.kernel.org/stable/c/35963b31821920908e397146502066f6b032c917
- https://git.kernel.org/stable/c/f1f7f36cf682fa59db15e2089039a2eeb58ff2ad
- https://git.kernel.org/stable/c/aad8bbd17a1d586005feb9226c2e9cfce1432e13
- https://git.kernel.org/stable/c/0ed074317b835caa6c03bcfa8f133365324673dc
- https://git.kernel.org/stable/c/4a7ba45b1a435e7097ca0f79a847d0949d0eb088
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