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 E75D643DA38 for ; Mon, 7 Sep 2026 22:59:31 +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=1788821973; cv=none; b=sKpZh+8IpuDS+b5X8MFxFfCoJ+ycuTFc9iLqXPmjByaIcxMZhbAVm1sbLOfTxgVhpLJE9DE2zVoWrtl/LX5M0WFYLyQjN1+ndHx1Io+V2nH4DxVYL1OVvzqnSWP+rbKR2Lws8vkMhuBWYkpt20FYyznqgwW4T5f+QZ7+N2TL/ic= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788821973; c=relaxed/simple; bh=vHEEnrnZj24hlT9PJ/d72YqWgZ+j0fWPy7HybQ+3MiU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JDsxbQY8eLs5zwK/HSQuo1n6pOPzWy+cIEvbi70DsGHOyOpzoWPcNvtGqFIfYXQfOPY1kb0oygsX97BhM4Lxhj3hhfdYnUPibVltCyrNhK9NosLAI04URobNcO14ZaWmq+zu+uD8ogUIa7lKzul5HKoscl/+fZ0oaA3rCEeSp+4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cF7jT0ji; 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="cF7jT0ji" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A21D1F00A3F; Mon, 7 Sep 2026 22:59:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788821971; bh=HoRvicOoZHwrArEaqntn3hNnMbMFYcRF9eeR3KVp1HM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cF7jT0jim8NE5q4UiatBzq6fjcAFZOv5ZG1VKgTqDcNPzpYLH4u8PQgXaO0Apcg5Q YvZA8LczPsjphNDP8R2yjeUnLnlBbyFRKNzLnL6HGOhbPv3r+Rw7KRjMLDk+3IE1Mm YoQgbhcKQVzozHWw/+QfE+5LDaLD8+kWnXlU3+3gTldJYlm5h/CSwRTAFJVU1sFg4a 6L1buoyLtQHfxUxr52JzXhSquP5AslRzCOeYBJ+3cCB1tsKAHFn+UI2xicWhjbLxts xEvJSmkMCrwG4bmvHuu40sXDFSdSVr4b4f3WAqqb1xbnjSeP0yii5osWrhjJ/uoDmk DUXpiWQAqmm/Q== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Jeff Layton , Sasha Levin Subject: [PATCH 6.18.y 4/4] NFSD: Prevent client use-after-free during close_lru reaping Date: Mon, 7 Sep 2026 18:59:27 -0400 Message-ID: <20260907225927.712336-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260907225927.712336-1-sashal@kernel.org> References: <2026090304-waking-garnish-23bc@gregkh> <20260907225927.712336-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 2330b788d732f43668b965b3105b37ceb276dfea ] An nfs4_openowner left on nn->close_lru after its final CLOSE keeps its last closed stateid in oo_last_closed_stid, holding only a raw pointer to its nfs4_client. The laundromat reaps timed-out entries, drops nn->client_lock, and calls nfs4_put_stid(), which dereferences the client through cl_lock. Nothing pins the client across that window, so a concurrent force_expire_client() can free it and nfs4_put_stid() reads freed memory. __destroy_client() hits the same race, walking clp->cl_openowners without cl_lock. Pin the client with cl_rpc_users before dropping client_lock, and skip clients already expiring. __destroy_client() then cleans up its own close_lru entries through release_last_closed_stateid(), so teardown no longer races the laundromat. Fixes: 217526e7ecc9 ("nfsd: protect the close_lru list and oo_last_closed_stid with client_lock") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260709-cel-v4-8-1d519d9be0cb@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4state.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 07da5353644e1..d8c44eddf38ed 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -7155,11 +7155,16 @@ nfs4_laundromat(struct nfsd_net *nn) if (!state_expired(<, oo->oo_time)) break; list_del_init(&oo->oo_close_lru); + clp = oo->oo_owner.so_client; + if (is_client_expired(clp)) + continue; stp = oo->oo_last_closed_stid; oo->oo_last_closed_stid = NULL; + atomic_inc(&clp->cl_rpc_users); spin_unlock(&nn->client_lock); nfs4_put_stid(&stp->st_stid); spin_lock(&nn->client_lock); + put_client_no_renew_locked(clp); } spin_unlock(&nn->client_lock); -- 2.53.0