bpf: Fix out-of-bounds write in trie_get_next_key()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix out-of-bounds write in trie_get_next_key() trie_get_next_key() allocates a node stack with size trie->max_prefixlen, while it writes (trie->max_prefixlen + 1) nodes to the stack when it has full paths from the root to leaves. For example, consider a trie with max_prefixlen is 8, and the nodes with key 0x00/0, 0x00/1, 0x00/2, ... 0x00/8 inserted. Subsequent calls to trie_get_next_key with _key with .prefixlen = 8 make 9 nodes be written on the node stack with size 8.

References

• https://git.kernel.org/stable/c/e8494ac079814a53fbc2258d2743e720907488ed
• https://git.kernel.org/stable/c/91afbc0eb3c90258ae378ae3c6ead3d2371e926d
• https://git.kernel.org/stable/c/590976f921723d53ac199c01d5b7b73a94875e68
• https://git.kernel.org/stable/c/86c8ebe02d8806dd8878d0063e8e185622ab6ea6
• https://git.kernel.org/stable/c/a035df0b98df424559fd383e8e1a268f422ea2ba
• https://git.kernel.org/stable/c/90a6e0e1e151ef7a9282e78f54c3091de2dcc99c
• https://git.kernel.org/stable/c/c4b4f9a9ab82238cb158fa4fe61a8c0ae21a4980
• https://git.kernel.org/stable/c/13400ac8fb80c57c2bfb12ebd35ee121ce9b4d21