From nobody Mon May 25 01:58:48 2026 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ECAB63ED3D3 for ; Tue, 19 May 2026 14:00:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.45 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779199225; cv=none; b=It0L9/dO0ceks3ZpBSt8kOtKuXkCHaLU7YRnuDGtBz3r2Y0eF4HQ+i0jL4aFdzjQfUyp7htqqRbTAbqwobuJeumgdO5tVUlY/f0tWC8GM2gbw/tHBgOGzAF8slAKPdW2vFqV63JGfSUKSmvnbltp4Ou85327icHu1/5O1IUhIGU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779199225; c=relaxed/simple; bh=rh00+8CkvhUf5L5qQeiUYys/cEAiNnU8gZcvDzmdR6Q=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=DzKZkIBeh6X09xxc66VFKMyLPPTcX/sgPo71kE0Wk252v10fSzM/sih5OwYj/vp2dKTn0JIenqlDB+lWSdpF7TFg7C7drcsz1E1ytFUAl3zo0n7n2UcH1kBwGPRhJAe1ttR27aXBzPktbyd43SG7czH+ngwyojZxK9GNP+9WdHc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=qIBsI1u1; arc=none smtp.client-ip=209.85.128.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qIBsI1u1" Received: by mail-wm1-f45.google.com with SMTP id 5b1f17b1804b1-488940ccfa6so245e9.1 for ; Tue, 19 May 2026 07:00:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779199222; x=1779804022; darn=vger.kernel.org; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:from:to:cc:subject:date:message-id:reply-to; bh=Qj6Q3RQDF1dvwe9sYLWhvH0vVhTSMw/WV5aqKETF4Bs=; b=qIBsI1u1rWRS66GIYQG7ye4vCbtT9RaWxIGm/NQPwbz2j7/CRZOMFoTYLiegznDeqc mgkCs7550vbiO19PvvLccjdCIXl2mJfIwXBOKNCdjWC5NlIjAz5FnuRPXbpWS0X3SIDn s+eHrGUWiUYTNhk1vbSy4CAfczPhObYT2Vx9+lT3hoy7xJzZ4hlyPSsRLzQU4pSgqfA1 W8praf34GV4Tz58AOPFrjx7Wsq4gk8Jdr1/i48jIb69ODP6Lq5MuhkoVe3l3oF2Xq6EW MITfyCcmoH/EBlgzYdifZm38lIY6HG2NcsT3GI/KqE/lCcVz2Cx81AXyuzm3XII5ln4V oqtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779199222; x=1779804022; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Qj6Q3RQDF1dvwe9sYLWhvH0vVhTSMw/WV5aqKETF4Bs=; b=I7yFGhiGSyXBmj0uvmh5rmPgWn1uYIPQyn9nd7xVN1v/HYu/i+Qdcbw1R2Rk0KDXjL gqXRWqjOXJrpq/KIP/72csXs7XphzJ3u2bjjTLXfrAmkTTuxocFdKOF3zk5/s1ea5PsQ WwSfdLR2ejM8sXuk24vsfmqB+m62ltIFuM2ZvKwsVK5X1pREHMAmxDVXAMHkYd4Hfhpr zZPncrQ37MMXpLrfSsY/IVMOzuEn7UBgEsf9IjyHVCmIRZ4udZoaUJhl02w6qyyEvwQT EpuqUSOi27oWllt5IzSbwHan3BfkpMqQxljP+oaWq6fVey/5rD3SZ5AMqHXGJBoC3c2x kS5w== X-Forwarded-Encrypted: i=1; AFNElJ/cS12v+BIalL9UtYooOKENDuNOtE36fNax8sVsvmAHLgeAEGbdT3O5vNXUmAfT5uxmwCxb8ELyqPv0Z70=@vger.kernel.org X-Gm-Message-State: AOJu0YxY+DFduOvzkEt9dMm2AXTKmvhhzo2OLCqmRbvrlGh2DLuIonmH RJObiQ+RqKH7mUtRsqK3P06cWI6C4gQBJXn1tc3b7L6LfDno1hBxrw101+8ZBzKGfg== X-Gm-Gg: Acq92OFsEvLY+ZQ1iLpptTBNpxJW1ZGNdOiZtE1D0RxaRQjorLKE6My/U0kqNfO9Ejg B1VaqTnxezlriT+/XarUaL6ecuSsFP8FibUOSUrixmFZavpdTD2lgw+RBzrIPSPbQc9NHjJuWDd 7AMFoEdnOBMzF+zFS4EZ23UY+KP/uPk2Q7AuNIuwGY/XCW3/CimNfwN389nbpYsIKaCPbulxfv4 eSlTs4/IauvIzmDBKg+g969PfsImr6MM5VQYJRMK+9SGEX8f+toRGBT3a9VAnsYZBe0ywd5ueDy Y/zshLr003ribN8zxJEw2f2AJyU+JCFW/1qaZL06z115oAroKD1C61Z1cNja/P4i15V5lZZroL/ VXuejCxsVZ65vhBsVnqWTys0DLd+LgzASU11GoSUuV7cwjBVhk3SrmUdB+8/9tuMMPwDFOicggw 6Lx4tIXMTGvrxLC974frx700HGFtHvoolIkMYo9ZzljzwbR/lno6WZZirjYSMMo9yps9drvYFJ X-Received: by 2002:a05:600c:1716:b0:477:86fd:fb49 with SMTP id 5b1f17b1804b1-48ffa5f3d4amr2992925e9.10.1779199221326; Tue, 19 May 2026 07:00:21 -0700 (PDT) Received: from localhost ([2a00:79e0:288a:8:c208:c046:d3db:6b00]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45da0a17a22sm46180982f8f.22.2026.05.19.07.00.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 May 2026 07:00:20 -0700 (PDT) From: Jann Horn Date: Tue, 19 May 2026 16:00:09 +0200 Subject: [PATCH] fuse: reject fuse_notify() pagecache ops on directories Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260519-fuse-dir-pagecache-v1-1-1f060c65930d@google.com> X-B4-Tracking: v=1; b=H4sIAOhsDGoC/x3MQQqAIBBA0avIrBtIU6muEi3EJptNiVIE4t2Tl m/xf4FMiSnDLAokejjzdTbIToA/3BkIeWsG1SvbGznhfmfCjRNGF8g7fxAOo3JGS21HZaGFMdH O7z9d1lo/XBar62QAAAA= X-Change-ID: 20260519-fuse-dir-pagecache-382a54146826 To: Miklos Szeredi Cc: Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Jann Horn X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=ed25519-sha256; t=1779199217; l=1640; i=jannh@google.com; s=20240730; h=from:subject:message-id; bh=rh00+8CkvhUf5L5qQeiUYys/cEAiNnU8gZcvDzmdR6Q=; b=iDn1y5baDHzNvdkad7LwoFZexvVnhokCz3wZmVRWkO3YZ/cefv06OcAjXDIHSHk5PIdC4bnRE j+yMRcD4jwUBgSgS0h/GxU3cJYSDlnJPBWa/Cz7HWvazYB4u/r7tRmW X-Developer-Key: i=jannh@google.com; a=ed25519; pk=AljNtGOzXeF6khBXDJVVvwSEkVDGnnZZYqfWhP1V+C8= The operations FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE allow the FUSE daemon to actively write/read pagecache contents. For directories with FOPEN_CACHE_DIR, the pagecache is used as kernel-internal cache storage, and userspace is not supposed to have direct access to this cache - in particular, fuse_parse_cache() will hit WARN_ON() if the cache contains bogus data. Reject FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE on directories with -EINVAL. Fixes: 5d7bc7e8680c ("fuse: allow using readdir cache") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn --- fs/fuse/dev.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 5dda7080f4a9..7096f53d335c 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1793,6 +1793,10 @@ static int fuse_notify_store(struct fuse_conn *fc, u= nsigned int size, inode =3D fuse_ilookup(fc, nodeid, NULL); if (!inode) goto out_up_killsb; + if (S_ISDIR(inode->i_mode)) { + err =3D -EINVAL; + goto out_iput; + } =20 mapping =3D inode->i_mapping; file_size =3D i_size_read(inode); @@ -1966,7 +1970,10 @@ static int fuse_notify_retrieve(struct fuse_conn *fc= , unsigned int size, =20 inode =3D fuse_ilookup(fc, nodeid, &fm); if (inode) { - err =3D fuse_retrieve(fm, inode, &outarg); + if (S_ISDIR(inode->i_mode)) + err =3D -EINVAL; + else + err =3D fuse_retrieve(fm, inode, &outarg); iput(inode); } up_read(&fc->killsb); --- base-commit: ab5fce87a778cb780a05984a2ca448f2b41aafbf change-id: 20260519-fuse-dir-pagecache-382a54146826 -- =20 Jann Horn