CVE-2026-45870: SUNRPC: auth_gss: fix memory leaks in XDR decoding error paths

CVE-2026-45870: SUNRPC: auth_gss: fix memory leaks in XDR decoding error paths

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2026-45870 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 5.10.252 with commit c81431b1b9fbd21e9a5a9211b5517b7295d18e6a
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 5.15.202 with commit caf7eff432e91a9eba1c79fa545c2f54be15d62b
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 6.1.165 with commit 64303b92d94c0c7845a273acd8d84b796d6f1db7
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 6.6.128 with commit df10f23defff22c8d55fe6db74f6e4ce927145bf
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 6.12.75 with commit b4af3806846778799cd4ab0766dc18341e777264
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 6.18.14 with commit d79b9097a6a2b91471b40755f1225364be5d85ff
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 6.19.4 with commit 3b56eb90feb8a3709417f5624f3871847d42bcb1
	Issue introduced in 3.10 with commit 1d658336b05f8697d6445834f8867f8ad5e4f735 and fixed in 7.0 with commit 3e6397b056335cc56ef0e9da36c95946a19f5118

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-45870
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/sunrpc/auth_gss/gss_rpc_xdr.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/c81431b1b9fbd21e9a5a9211b5517b7295d18e6a
	https://git.kernel.org/stable/c/caf7eff432e91a9eba1c79fa545c2f54be15d62b
	https://git.kernel.org/stable/c/64303b92d94c0c7845a273acd8d84b796d6f1db7
	https://git.kernel.org/stable/c/df10f23defff22c8d55fe6db74f6e4ce927145bf
	https://git.kernel.org/stable/c/b4af3806846778799cd4ab0766dc18341e777264
	https://git.kernel.org/stable/c/d79b9097a6a2b91471b40755f1225364be5d85ff
	https://git.kernel.org/stable/c/3b56eb90feb8a3709417f5624f3871847d42bcb1
	https://git.kernel.org/stable/c/3e6397b056335cc56ef0e9da36c95946a19f5118