From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2B6B031619A; Mon, 13 Apr 2026 16:51:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776099112; cv=none; b=j+yUaDGWzYpQxkB+XNUrTAuPkXBB5P7S2gYzeWOD9hIfSqdflivuEDt7PtRS1xurjO9b3HLnAxh58iwB2qkUVO3iODDfYMZ9FdSt7pW050+KfoaEcfnCWGlTHbes2eXILRf3DmtMQ6/9dGmuyxwlTUOp8PvdIo7YWT0faPQZw1I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776099112; c=relaxed/simple; bh=yCUW5IzQmnM9KhKsY5N7cFQldOsB/VBYxHruPDkhv0o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C8nvbFr0Vb6ePms2SAEXQbHvxYsZiAXvyoSfgKIMt3wIk8u76rSs3cv6RZ442+tYZ3HBMeDCYophrgosXJfBIisxgLua5mO2Pnx/S2PtMT64KMFKU5boPswF90VtzoFcaHTCOJEVRZXaCGUhPJq0SMYC95VdDiB580rJGLsOXbg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=H0RN2zzz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="H0RN2zzz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE0BC2BCAF; Mon, 13 Apr 2026 16:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776099111; bh=yCUW5IzQmnM9KhKsY5N7cFQldOsB/VBYxHruPDkhv0o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H0RN2zzzcGupySOaV5uvebf0ycSnJdQEgd2ea6P0mhZ4u6Y6KrnhYwUOTE6jdFLLv GirKFIwp26Di+lGzHordbTCYpN8p2sHj0cnLNlSHUYRU6mMCVDYpCi13Faw9FVGI4a z9QbWACK8vu60WBAPHQ5x1WLYEyPoZeR2qOmtGIw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Misbah Anjum N , Jeff Layton , NeilBrown , Olga Kornievskaia , Chuck Lever , Sasha Levin Subject: [PATCH 5.10 183/491] NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd Date: Mon, 13 Apr 2026 17:57:08 +0200 Message-ID: <20260413155825.913298947@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155819.042779211@linuxfoundation.org> References: <20260413155819.042779211@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chuck Lever [ Upstream commit e7fcf179b82d3a3730fd8615da01b087cc654d0b ] The /proc/fs/nfs/exports proc entry is created at module init and persists for the module's lifetime. exports_proc_open() captures the caller's current network namespace and stores its svc_export_cache in seq->private, but takes no reference on the namespace. If the namespace is subsequently torn down (e.g. container destruction after the opener does setns() to a different namespace), nfsd_net_exit() calls nfsd_export_shutdown() which frees the cache. Subsequent reads on the still-open fd dereference the freed cache_detail, walking a freed hash table. Hold a reference on the struct net for the lifetime of the open file descriptor. This prevents nfsd_net_exit() from running -- and thus prevents nfsd_export_shutdown() from freeing the cache -- while any exports fd is open. cache_detail already stores its net pointer (cd->net, set by cache_create_net()), so exports_release() can retrieve it without additional per-file storage. Reported-by: Misbah Anjum N Closes: https://lore.kernel.org/linux-nfs/dcd371d3a95815a84ba7de52cef447b8@linux.ibm.com/ Fixes: 96d851c4d28d ("nfsd: use proper net while reading "exports" file") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Reviewed-by: NeilBrown Tested-by: Olga Kornievskaia Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfsctl.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -152,9 +152,19 @@ static int exports_net_open(struct net * seq = file->private_data; seq->private = nn->svc_export_cache; + get_net(net); return 0; } +static int exports_release(struct inode *inode, struct file *file) +{ + struct seq_file *seq = file->private_data; + struct cache_detail *cd = seq->private; + + put_net(cd->net); + return seq_release(inode, file); +} + static int exports_nfsd_open(struct inode *inode, struct file *file) { return exports_net_open(inode->i_sb->s_fs_info, file); @@ -164,7 +174,7 @@ static const struct file_operations expo .open = exports_nfsd_open, .read = seq_read, .llseek = seq_lseek, - .release = seq_release, + .release = exports_release, }; static int export_features_show(struct seq_file *m, void *v) @@ -1421,7 +1431,7 @@ static const struct proc_ops exports_pro .proc_open = exports_proc_open, .proc_read = seq_read, .proc_lseek = seq_lseek, - .proc_release = seq_release, + .proc_release = exports_release, }; static int create_proc_exports_entry(void)