Vulnerability in Linux

[ Description ]Official description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix heap out-of-bounds write in krb5_authenticate() In krb5_authenticate(), out_len is calculated to determine available headroom in response_buf for the incoming Kerberos AP-REP token. However, when SMB2_SESSION_SETUP is processed as a non-first element of a compounded SMB2 request, the calculation omits work->next_smb2_rsp_hdr_off. This causes out_len to overstate remaining buffer headroom by the cumulative size of prior responses in the compound chain. Consequently, the length check in ksmbd_krb5_authenticate() (*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy() to write the AP-REP blob past the end of response_buf into adjacent kernel heap memory. Fix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len, ensuring it accurately reflects physical remaining buffer space.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0
• git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23
• git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06
• git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059
• git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a