From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794061844; b=Cas5XLJL12WPDWs8G7tUNx+E9g+zJFxYFoIJuwtcXxRb2ChisNQokLuHHnpBaXnjEe72 J3xNM3IDKDWViAhcrhg6yAU/jGrmkQzxQ/g34LrSkMD6PXa0WlZPEzhxA8xsjSkcOzeGc MFVCqnChL32BG8kR6x44fBuT4K0pVclLjObfVzTWC1gf4YnlaphpDh/Oy82XQAJcLr59c Qd26B++A4RAF2kjY2p0Bj3djie4gaGea8b6MDeeTl1MsCwcQB1eFmOW+Y4BhkwN+XqZZE hK86uHndyKkgPiwFCRYL8QaCcVEJ/sbzrAqNFgxuniWKmoKpYP8wFIFrwEPBXvS1nHA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061844; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=9nUTUowUAnoyeAKWdEjTIn1cUXjIYYQnz2q7jPDgv4Q=; b=LpFuRzGrIRVua8tMtzg1LqFjPBEusBQsh1el2nNlNBgD16Pw7H6E3c0BEMHY1abFRx+M XDk89DCDKV/8Vyn4qYTGtu0HgHgTytqa2kuJ+hPTl3+WlFL13SjLU/8qzFAIgc6i1cJsJ BSItFI907vRt6q0eBmM9UsFf8u8JARE5nDqyCo0RtvuX0qQ+7djYEiwsX7F7lYlVyvUk5 f2NsFLqpKkanwTZdOOxlJeaDHWopAM+x7pjl52Pnfo0emOe6ESLzxDXTGpRfJnSo2DSq0 6l0WjWLHsYYoIYpUzYc8wMcTX/0YeNdxg7BGMEdeujw20a0zMffFyzqiBjG5XGCE1PA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=R7uaWRvT; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 506CB606A32C; Sat, 7 Nov 2026 14:30:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=R7uaWRvT Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF8ED1F0089F; Sat, 7 Nov 2026 14:30:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061844; bh=9nUTUowUAnoyeAKWdEjTIn1cUXjIYYQnz2q7jPDgv4Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=R7uaWRvTNKnTjD7qRJAwuJM6waJJwX1yZC7hnwPOZF7uZn0S36VEqquFAftU21bIg 9rgkgQslhtAzMOXmNVJK7AhQkcW3O3C4ns0p0I5SbzoUiwXLnfdSjgOiaaDQGl3jmM IPEZZ7r4ppT/LfbX+DUqnwYzm9986AEwkN4agrEI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Josef Bacik , Amir Goldstein , Sasha Levin Subject: [PATCH 6.12 0862/1536] ovl: hold a reference on the parent in readdir Date: Sat, 7 Nov 2026 08:47:58 -0500 Message-ID: <20261107135021.758724030@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Mason commit 16d319e12328acafeafd3eecdf09c46d7fb43452 upstream. Listing a directory on an overlay uses a freed dentry and crashes the kernel when a lookup moves the directory at the same time. Code that can sleep may only use d_parent without a reference while something stops a move of the dentry. ovl_iterate_real(), ovl_need_adjust_d_ino() and ovl_cache_update() use the d_parent of the listed directory and hold only the lock of that directory. When a lookup finds the directory under another parent after a change to a layer, d_splice_alias() moves it without that lock and drops its reference on the old parent. With a delay in ovl_iterate_real(), getdents64 on an overlay directory raced a rename in the lower layer and a lookup that moved its dentry, and after an rmdir of the old parent KASAN reported a use-after-free in security_inode_getattr(). Fix this by using dget_parent() in the three functions. Fixes: b5efccbe0a12 ("ovl: constant d_ino across copy up") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason Signed-off-by: Josef Bacik [amir: fix comments in ovl_need_adjust_d_ino()] Signed-off-by: Amir Goldstein [backport: no ovl_need_adjust_d_ino(), take the parent with dget_parent() in ovl_iterate() and test a local flag] Signed-off-by: Amir Goldstein Signed-off-by: Sasha Levin --- fs/overlayfs/readdir.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 6931cbc1042c3..5d912f887aac7 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -486,8 +486,8 @@ static int ovl_cache_update(const struct path *path, struct ovl_cache_entry *p, goto get; } if (p->len == 2 && p->name[1] == '.') { - /* we shall not be moved */ - this = dget(dir->d_parent); + /* d_splice_alias() can move even a locked dir */ + this = dget_parent(dir); goto get; } } @@ -711,6 +711,7 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx) struct dentry *dir = file->f_path.dentry; struct ovl_fs *ofs = OVL_FS(dir->d_sb); const struct ovl_layer *lower_layer = ovl_layer_lower(dir); + struct dentry *parent; struct ovl_readdir_translate rdt = { .ctx.actor = ovl_fill_real, .orig_ctx = ctx, @@ -721,18 +722,26 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx) if (rdt.xinobits && lower_layer) rdt.fsid = lower_layer->fsid; - if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) { + /* + * The lock on dir does not stop d_splice_alias() from moving it to + * another parent, which drops the reference dir holds on this one. + */ + parent = dget_parent(dir); + if (OVL_TYPE_MERGE(ovl_path_type(parent))) { struct kstat stat; struct path statpath = file->f_path; - statpath.dentry = dir->d_parent; + statpath.dentry = parent; err = vfs_getattr(&statpath, &stat, STATX_INO, 0); - if (err) + if (err) { + dput(parent); return err; + } WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev); rdt.parent_ino = stat.ino; } + dput(parent); if (ovl_is_impure_dir(file)) { rdt.cache = ovl_cache_get_impure(&file->f_path); @@ -761,6 +770,10 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) ovl_dir_reset(file); if (od->is_real) { + struct dentry *parent = dget_parent(dentry); + bool parent_merge = OVL_TYPE_MERGE(ovl_path_type(parent)); + + dput(parent); /* * If parent is merge, then need to adjust d_ino for '..', if * dir is impure then need to adjust d_ino for copied up @@ -768,8 +781,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) */ if (ovl_xino_bits(ofs) || (ovl_same_fs(ofs) && - (ovl_is_impure_dir(file) || - OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) { + (ovl_is_impure_dir(file) || parent_merge))) { err = ovl_iterate_real(file, ctx); } else { err = iterate_dir(od->realfile, ctx); -- 2.53.0