CVE-2023-52767 Information

Description

In the Linux kernel the following vulnerability has been resolved:

tls: fix NULL deref on tls_sw_splice_eof() with empty record

syzkaller discovered that if tls_sw_splice_eof() is executed as part of sendfile() when the plaintext/ciphertext sk_msg are empty the send path gets confused because the empty ciphertext buffer does not have enough space for the encryption overhead. This causes tls_push_record() to go on the split = true path (which is only supposed to be used when interacting with an attached BPF program) and then get further confused and hit the tls_merge_open_record() path which then assumes that there must be at least one populated buffer element leading to a NULL deref.

It is possible to have empty plaintext/ciphertext buffers if we previously bailed from tls_sw_sendmsg_locked() via the tls_trim_both_msgs() path. tls_sw_push_pending_record() already handles this case correctly; let’s do the same check in tls_sw_splice_eof().

Reference

https://git.kernel.org/stable/c/944900fe2736c07288efe2d9394db4d3ca23f2c9 https://git.kernel.org/stable/c/2214e2bb5489145aba944874d0ee1652a0a63dc8 https://git.kernel.org/stable/c/53f2cb491b500897a619ff6abd72f565933760f0