Linux Kernel up to 6.6.3 tls_sw_splice_eof null pointer dereference

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.6.3. This affects the function tls_sw_splice_eof. Such manipulation leads to null pointer dereference. This vulnerability is documented as CVE-2023-52767. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.3. It has been rated as critical. Affected by this issue is the function tls_sw_splice_eof. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

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().

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2023-52767. Technical details are known, but there is no available exploit.

Upgrading to version 6.6.4 eliminates this vulnerability. Applying the patch 944900fe2736/2214e2bb5489/53f2cb491b50 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

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