From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D0A933815D0 for ; Tue, 8 Sep 2026 19:41:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788896465; cv=none; b=Z3F9w9uJvZdpO17UsluVV60+B/XCrkdVUJ95tnh+S5friM7/V4YbyQUNdcYsOp7GGfcpivMX8W8HExS4jWbGU2q8jE9kDuClS7XBGAx2LtqQ1vf1PsGBKwSxMOwFFoYtnLyIPQUpR/Bx7MO3lxvoc4ZJTjk1y5vqQ6n757yTQSI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788896465; c=relaxed/simple; bh=mQ/MoC96/gYtvtlsm26R4ObjM0FA7CPk/rr/6pUfyw8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FYrV45GmVyI1Ff45p5FUlGZUN7lWJVWDTjAlPimx9qQojyXFGm1eNKOis8Y8GVma3wPLsdqJnjIDyA10fVjPqWsya7k281ZAoy3OviueBJuYaNArHW5SKeUJbUWbyjTDqbglKOhkVlZRGvoSikq2uPLimbWIgOc3cUXm2n0CaDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YXvqJF5e; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YXvqJF5e" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10CC01F00A3D; Tue, 8 Sep 2026 19:41:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788896463; bh=kjqr+DbiTfNtzU/eV+cPXkxxGRbKXya9ypK1pNLmU/Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=YXvqJF5eMcLISGD35hfstrVP2Karc4+XO9HZlXiX1weHRmkcaGtMp/HDWXgZJbZy4 LRkHdEHU5uVnCsCDJtfNQJn6KUgYtpaUD+3yUAY6vINqbztBDly5Z1pNVBxKrK5bzQ IVG7wAWc1KPWW2e1hILhRXojzExUmNhB6P4upYcfYdnoNyioXYY0qUR67HHcsoftRp xQjnU8YkXav7gzzceQ6dq7HSNSaZJG15dpKhLcgOqfq6D2a3UP42FYdNgQJ3SrP9+H FYKDovGrs9NHFAiSvKpIzQhdQb20M6FZcd0iU1hz7JF6VzGJOTYVR+VVBfLqs+izMT sUTFMa/34JMDw== From: Sasha Levin To: stable@vger.kernel.org Cc: Chris Mason , Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.6.y] SUNRPC: fix gssx_dec_option_array error path bugs Date: Tue, 8 Sep 2026 15:41:01 -0400 Message-ID: <20260908194101.376578-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090301-irritant-cage-55aa@gregkh> References: <2026090301-irritant-cage-55aa@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chris Mason [ Upstream commit 5e9a94539b1ec17a89177d952badfd0d844d694a ] Four coupled defects in the gssx XDR option-array decoder make the error paths unsafe: a NULL deref in the caller, a refcount leak on the decoded group_info, and a latent use-after-free that the leak fix would otherwise expose. gssx_dec_option_array() sets oa->count = 1 before allocating oa->data. If that allocation fails, -ENOMEM is returned with oa->count == 1 and oa->data == NULL. All other error paths jump to free_oa: which frees oa->data and NULLs it but also leaves oa->count == 1. The caller trusts the count: gssp_accept_sec_context_upcall() gssx_dec_accept_sec_context() gssx_dec_option_array() /* fails, count=1 data=NULL */ data = res.options.data[0].value /* NULL deref */ Independently, free_creds: releases the partially decoded svc_cred with a bare kfree(creds). gssx_dec_linux_creds() installs a groups_alloc() result into creds->cr_group_info; that object is kvmalloc-backed and refcounted, and only put_group_info() reaches kvfree(). A plain kfree(creds) drops the wrapper and leaks the group_info allocation. The natural fix for the leak is to call free_svc_cred(creds) before kfree(creds), but free_svc_cred() invokes put_group_info() on creds->cr_group_info unconditionally when non-NULL. The existing out_free_groups: path in gssx_dec_linux_creds() already called groups_free() on that pointer without clearing it, so once free_svc_cred() is wired in, the subsequent put_group_info() would touch freed memory. Fix all four together: - Move the oa->count = 1 assignment below the oa->data allocation so it is never set when oa->data is NULL. - Reset oa->count to 0 at free_oa: so count and data stay coherent and the caller sees an empty option array. - Call free_svc_cred(creds) before kfree(creds) at free_creds: so the refcounted cr_group_info is released. free_svc_cred() either NULL-guards each field explicitly (cr_group_info has an if() check) or delegates to a helper that is NULL-safe itself (kfree for the string fields, gss_mech_put() which guards with if(gm) at gss_mech_switch.c:342), so it is safe to call on a partially decoded svc_cred where only cr_uid/cr_gid/cr_group_info have been written and everything else is zero from kzalloc. - In gssx_dec_linux_creds()'s out_free_groups: path, release cr_group_info with put_group_info() rather than groups_free() so the teardown matches free_svc_cred()'s refcount-aware path, and clear the pointer so a later free_svc_cred() on the same creds does not release it a second time. Fixes: 3cfcfc102a5e ("SUNRPC: fix some memleaks in gssx_dec_option_array") Cc: stable@vger.kernel.org Assisted-by: kres (claude-opus-4-7) Signed-off-by: Chris Mason Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260528-tier2-v1-2-d026a1415e0b@oracle.com Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- net/sunrpc/auth_gss/gss_rpc_xdr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/sunrpc/auth_gss/gss_rpc_xdr.c b/net/sunrpc/auth_gss/gss_rpc_xdr.c index ee91f4d641e6f..ac9ae42a69762 100644 --- a/net/sunrpc/auth_gss/gss_rpc_xdr.c +++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c @@ -222,7 +222,8 @@ static int gssx_dec_linux_creds(struct xdr_stream *xdr, return 0; out_free_groups: - groups_free(creds->cr_group_info); + put_group_info(creds->cr_group_info); + creds->cr_group_info = NULL; return err; } @@ -242,12 +243,12 @@ static int gssx_dec_option_array(struct xdr_stream *xdr, return 0; /* we recognize only 1 currently: CREDS_VALUE */ - oa->count = 1; - oa->data = kmalloc(sizeof(struct gssx_option), GFP_KERNEL); if (!oa->data) return -ENOMEM; + oa->count = 1; + creds = kzalloc(sizeof(struct svc_cred), GFP_KERNEL); if (!creds) { err = -ENOMEM; @@ -294,8 +295,10 @@ static int gssx_dec_option_array(struct xdr_stream *xdr, return 0; free_creds: + free_svc_cred(creds); kfree(creds); free_oa: + oa->count = 0; kfree(oa->data); oa->data = NULL; return err; -- 2.53.0