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 BD4B14086A for ; Wed, 9 Sep 2026 00:52:15 +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=1788915137; cv=none; b=OKv2yk9zSr9DhG7CoFQvz/tufa03jWMRrYhUDMgr5udNiD1uxFH2k3oIDrbeb8TU/GzPHz3XxtzY7s3sFLl4OB/lVZHjuDpI5Cj1D3GnA+UPaHpq9ydZ03Dhl7H6pVSor2/zksmJhPUtxK/BAi3Z3GDRD8I+RnDjio0mB2x41WA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788915137; c=relaxed/simple; bh=gkbcMsXPf3VLBm8ZY152fGe/f7tv/lxEbM5BN4IZlFg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WouFdengLdbkoG0y73zlYNNipK8ikYKHoTsYFVhSu91q4V3hpWdUo1NJ8CyNOj5zoy/H+R1HR6VpD9Mszosu4wDIrxIe6an/ZesCd0ATXvFbs7EeZZpnTm9Bj+Ni6WNePsYIyJMxTvXSkXeO6i5xXEIOwvPBtwjiMgJRX3CePRM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hBLI7y+F; 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="hBLI7y+F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81D791F00AC4; Wed, 9 Sep 2026 00:52:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788915135; bh=33d1uM9j9QuYZSDprE2nbShZH2Ok6VWgV63TVY4HKx0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hBLI7y+FqeytYpJ580nC4sw9XTq5eTFdE7sim9tPhL/Ywnt8v8Aj1wUwXP2u/32NS mjlM4raE5Z+51XSEpr3ysUGdUQbXLSMQphiQwNIK+bkEnRUHWUdkq+VCufcdZL7PJC aDBUQpSG9RYLeZkb5LG33ZXYEe94J6eiygaIRZ3oL9zmb+0eYfsMTw6AVCXtx1qlK0 3OG6cIfsUATrIm5Ej5hSF9t8nkILCBeaA0JXxXxOOwB48WKII7ahrepx9FMw2HysB4 Lb4foUZqvXC7RzGfG7PlFgjZHK/ulu6oZxmcweumGy3ty35Fvp95Rcz5SILHIOd4UM bjCx70XLEOUKQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Luxiao Xu , Yuan Tan , Xin Liu , Ren Wei , Trond Myklebust , Sasha Levin Subject: [PATCH 5.15.y 4/4] sunrpc: fix use-after-free in __rpc_clnt_handle_event and __rpc_clnt_remove_pipedir Date: Tue, 8 Sep 2026 20:52:10 -0400 Message-ID: <20260909005210.805789-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260909005210.805789-1-sashal@kernel.org> References: <2026090318-squad-abnormal-f798@gregkh> <20260909005210.805789-1-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: Luxiao Xu [ Upstream commit 932a8cf6abb2b2f8677b79153a823108d8861fe2 ] Normal client creation goes through rpc_setup_pipedir(), which records clnt->pipefs_sb, but the mount-event path in __rpc_clnt_handle_event() calls rpc_setup_pipedir_sb() directly and never refreshes that field. The umount path also removes the directory without clearing clnt->pipefs_sb. After a late pipefs mount or any remount, rpc_clnt_remove_pipedir() compares the current superblock against a stale pipefs_sb pointer and skips cleanup, leaving pipefs dentries whose inode private data still points at a freed rpc_clnt, leading to a potential use-after-free during subsequent rpc_info_open() or rpc_show_info() calls. Fix this by properly updating clnt->pipefs_sb upon mount events and clearing it during unmount or failure paths. Fixes: bfca5fb4e97c ("SUNRPC: Fix RPC client cleaned up the freed pipefs dentries") Cc: stable@vger.kernel.org Reported-by: Yuan Tan Reported-by: Xin Liu Reviewed-by: Ren Wei Assisted-by: Codex:gpt-5.4 Signed-off-by: Luxiao Xu Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- net/sunrpc/clnt.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 458c0eb9fa52e..82ecc1e9dd13b 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -101,7 +101,10 @@ static void rpc_unregister_client(struct rpc_clnt *clnt) static void __rpc_clnt_remove_pipedir(struct rpc_clnt *clnt) { - rpc_remove_client_dir(clnt); + if (clnt->pipefs_sb) { + rpc_remove_client_dir(clnt); + clnt->pipefs_sb = NULL; + } } static void rpc_clnt_remove_pipedir(struct rpc_clnt *clnt) @@ -182,19 +185,28 @@ static int rpc_clnt_skip_event(struct rpc_clnt *clnt, unsigned long event) } static int __rpc_clnt_handle_event(struct rpc_clnt *clnt, unsigned long event, - struct super_block *sb) + struct super_block *sb) { + int err = 0; + switch (event) { case RPC_PIPEFS_MOUNT: - return rpc_setup_pipedir_sb(sb, clnt); + clnt->pipefs_sb = sb; + err = rpc_setup_pipedir_sb(sb, clnt); + if (err) + clnt->pipefs_sb = NULL; + break; case RPC_PIPEFS_UMOUNT: - __rpc_clnt_remove_pipedir(clnt); + if (clnt->pipefs_sb == sb) { + __rpc_clnt_remove_pipedir(clnt); + clnt->pipefs_sb = NULL; + } break; default: printk(KERN_ERR "%s: unknown event: %ld\n", __func__, event); return -ENOTSUPP; } - return 0; + return err; } static int __rpc_pipefs_event(struct rpc_clnt *clnt, unsigned long event, -- 2.53.0