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 EABEF2628D; Wed, 20 May 2026 17:31:15 +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=1779298277; cv=none; b=rpw0trBjPV59O+gbeqTw5qc7rwYfmADXzONSIOYa5MYhAl5v252SaXuR3i35edLSa0MBXv4wdkyQMCTkJlEMtl7uir8J9iNnb6+QJCsqUf59so+RqU4us+bKSFaI4KtHw2Plc7Mqej1jcDX5pZImF/DwrxdfuLyGNw3lq5HAbQY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779298277; c=relaxed/simple; bh=ccu3uSTK7ZQ3VaRZ+7rMlmnV9SahNPdgP9Ohn3EU68A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SQcd6rmU88RdApmzyDazj5wZjMkcBMiIO1oTOnuEZUQgHr8txgqE98jU1AAW/HCZcBrE37BAWkuDBV1S08as1uOa6eoXr12Hn/XHCkTj6E1NEYz75HkXy7sG0uOeoAk5bH6HmtDOTOaiDQ7TGc5LMGemLAfCy+PPUJndE7+4O/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rX/JTETn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rX/JTETn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C20B1F000E9; Wed, 20 May 2026 17:31:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779298275; bh=pPLVNXBAak6HwoKDGODmjDsOwIgk/YUS1nA5DJ81GDc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rX/JTETnn9SQKAJKmWFLsedHMASVM1q25XNiQfNMdH6lt9MSes/nDBacDrUtOgL2P QOqiSTztyZtHE00sBjKmMTHlKZ6SSyT+lKOG+giyy8v+BgeMkzgBFtfxIpvYsx9PsL xGvIOFQKWMFAYOGEsY6vAD2ct+VBcw5m0YcWP/fM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+fdebb2dc960aa56c600a@syzkaller.appspotmail.com, Luis Henriques , Miklos Szeredi , Sasha Levin Subject: [PATCH 6.18 347/957] fuse: fix uninit-value in fuse_dentry_revalidate() Date: Wed, 20 May 2026 18:13:50 +0200 Message-ID: <20260520162142.056223919@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162134.554764788@linuxfoundation.org> References: <20260520162134.554764788@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luis Henriques [ Upstream commit 5a6baf204610589f8a5b5a1cd69d1fe661d9d3cd ] fuse_dentry_revalidate() may be called with a dentry that didn't had ->d_time initialised. The issue was found with KMSAN, where lookup_open() calls __d_alloc(), followed by d_revalidate(), as shown below: ===================================================== BUG: KMSAN: uninit-value in fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394 fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394 d_revalidate fs/namei.c:1030 [inline] lookup_open fs/namei.c:4405 [inline] open_last_lookups fs/namei.c:4583 [inline] path_openat+0x1614/0x64c0 fs/namei.c:4827 do_file_open+0x2aa/0x680 fs/namei.c:4859 [...] Uninit was created at: slab_post_alloc_hook mm/slub.c:4466 [inline] slab_alloc_node mm/slub.c:4788 [inline] kmem_cache_alloc_lru_noprof+0x382/0x1280 mm/slub.c:4807 __d_alloc+0x55/0xa00 fs/dcache.c:1740 d_alloc_parallel+0x99/0x2740 fs/dcache.c:2604 lookup_open fs/namei.c:4398 [inline] open_last_lookups fs/namei.c:4583 [inline] path_openat+0x135f/0x64c0 fs/namei.c:4827 do_file_open+0x2aa/0x680 fs/namei.c:4859 [...] ===================================================== Reported-by: syzbot+fdebb2dc960aa56c600a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69917e0d.050a0220.340abe.02e2.GAE@google.com Fixes: 2396356a945b ("fuse: add more control over cache invalidation behaviour") Signed-off-by: Luis Henriques Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin --- fs/fuse/dir.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 77982fdbcf278..98b174bd802f0 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -455,6 +455,11 @@ static int fuse_dentry_init(struct dentry *dentry) fd->dentry = dentry; RB_CLEAR_NODE(&fd->node); dentry->d_fsdata = fd; + /* + * Initialising d_time (epoch) to '0' ensures the dentry is invalid + * if compared to fc->epoch, which is initialized to '1'. + */ + dentry->d_time = 0; return 0; } -- 2.53.0