ksmbd: avoid out of bounds access in decode_preauth_ctxt()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: avoid out of bounds access in decode_preauth_ctxt() Confirm that the accessed pneg_ctxt->HashAlgorithms address sits within the SMB request boundary; deassemble_neg_contexts() only checks that the eight byte smb2_neg_context header + (client controlled) DataLength are within the packet boundary, which is insufficient. Checking for sizeof(struct smb2_preauth_neg_context) is overkill given that the type currently assumes SMB311_SALT_SIZE bytes of trailing Salt.

References

• https://git.kernel.org/stable/c/39f5b4b313b445c980a2a295bed28228c29228ed
• https://git.kernel.org/stable/c/a2f6ded41bec1d3be643c80a5eb97f1680309001
• https://git.kernel.org/stable/c/f02edb9debbd36f44efa7567031485892c7df60d
• https://git.kernel.org/stable/c/e7067a446264a7514fa1cfaa4052cdb6803bc6a2