SUNRPC: reject duplicate CREDS_VALUE options

Summary

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: reject duplicate CREDS_VALUE options gssx_dec_option_array() walks the wire-supplied option array and, for every entry whose name matches CREDS_VALUE, calls gssx_dec_linux_creds() on the same struct svc_cred. That helper unconditionally installs a fresh groups_alloc() result into creds->cr_group_info without releasing whatever pointer was already there: for (i = 0; i < count; i++) { ... decode name ... if (length == sizeof(CREDS_VALUE) && memcmp(p, CREDS_VALUE, sizeof(CREDS_VALUE)) == 0) { err = gssx_dec_linux_creds(xdr, creds); ... } } A reply that carries two CREDS_VALUE entries therefore overwrites cr_group_info on the second iteration and orphans the group_info allocated by the first call. The earlier free_creds path only releases the last cr_group_info via free_svc_cred(), so the first allocation's refcount stays at one and its kvmalloc-backed storage is leaked. No in-tree caller of gssp_accept_sec_context_upcall() expects more than one CREDS_VALUE per reply. Fix by tracking whether a CREDS_VALUE option has already been decoded and returning -EINVAL on any subsequent match, so the free_creds path releases the single group_info that was installed.

Timeline

1. Sep 11, 2026, 7:44 PM UTCCVE published
2. Oct 30, 2026, 12:32 PM UTCRecord last updated

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  3.10

• KernelLinux

  From 3.10.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8