SUNRPC: auth_gss: fix memory leaks in XDR decoding error paths

Overview

In the Linux kernel, the following vulnerability has been resolved:

SUNRPC: auth_gss: fix memory leaks in XDR decoding error paths

The gssx_dec_ctx(), gssx_dec_status(), and gssx_dec_name() functions allocate memory via gssx_dec_buffer(), which calls kmemdup(). When a subsequent decode operation fails, these functions return immediately without freeing previously allocated buffers, causing memory leaks.

The leak in gssx_dec_ctx() is particularly relevant because the caller (gssp_accept_sec_context_upcall) initializes several buffer length fields to non-zero values, resulting in memory allocation:

struct gssx_ctx rctxh = {
    .exported_context_token.len = GSSX_max_output_handle_sz,
    .mech.len = GSS_OID_MAX_LEN,
    .src_name.display_name.len = GSSX_max_princ_sz,
    .targ_name.display_name.len = GSSX_max_princ_sz
};

If, for example, gssx_dec_name() succeeds for src_name but fails for targ_name, the memory allocated for exported_context_token, mech, and src_name.display_name remains unreferenced and cannot be reclaimed.

Add error handling with goto-based cleanup to free any previously allocated buffers before returning an error.

Affected

• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < c81431b1b9fbd21e9a5a9211b5517b7295d18e6a
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < caf7eff432e91a9eba1c79fa545c2f54be15d62b
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < 64303b92d94c0c7845a273acd8d84b796d6f1db7
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < df10f23defff22c8d55fe6db74f6e4ce927145bf
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < b4af3806846778799cd4ab0766dc18341e777264
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < d79b9097a6a2b91471b40755f1225364be5d85ff
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < 3b56eb90feb8a3709417f5624f3871847d42bcb1
• Linux >= 1d658336b05f8697d6445834f8867f8ad5e4f735 < 3e6397b056335cc56ef0e9da36c95946a19f5118
• Linux 3.10

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.