Description

In the Linux kernel, the following vulnerability has been resolved: bpf: fix end-of-list detection in cgroup_storage_get_next_key() list_next_entry() never returns NULL -- when the current element is the last entry it wraps to the list head via container_of(). The subsequent NULL check is therefore dead code and get_next_key() never returns -ENOENT for the last element, instead reading storage->key from a bogus pointer that aliases internal map fields and copying the result to userspace. Replace it with list_entry_is_head() so the function correctly returns -ENOENT when there are no more entries.

References 8

• git.kernel.org https://git.kernel.org/stable/c/0f3d9dd5e1fd52b39e25328307c6a694e994ffe3
• git.kernel.org https://git.kernel.org/stable/c/26d3339e465e54107bd85884341d1609c5300d6a
• git.kernel.org https://git.kernel.org/stable/c/2c88b2d96e1d4d0c7c4589a4593d4cdee6d332d6
• git.kernel.org https://git.kernel.org/stable/c/32ce55d424395904986f5066f8755f6cb9993377
• git.kernel.org https://git.kernel.org/stable/c/5828b9e5b272ecff7cf5d345128d3de7324117f7
• git.kernel.org https://git.kernel.org/stable/c/85a2f30e40f7468db732f55659bc6318874f49af
• git.kernel.org https://git.kernel.org/stable/c/b4b5a20bed82130da2f2818f04d52378952fbd0b
• git.kernel.org https://git.kernel.org/stable/c/fc39753b7f92e09177777e9c648afe5aa3abb81f

Remediation