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 D01E71C57B1; Tue, 15 Oct 2024 12:06:57 +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=1728994017; cv=none; b=AwWzUFsCW89aVbRnByjOxx36DqTilMj3NQOR/m8GbkJfTOMBMPHuDyfC0X44z5N3bvvk2aahWxY5nAwizixS3Op6Vczz9ziA/7T1AyG/lWU1BZZGESiGCim8hY3gCoX1YczOoecMFZoQJqIdH0aSEWGsO1tLTu62Lq3H2T/SU0w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728994017; c=relaxed/simple; bh=nCb9zRnRtsxhqoCJUijrXZAYYIgy7z4yWS8divQUmPo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sYoA0Jsf2SxaSMNdfyQGoFoCA8wy9GXbBz67uxUXiTJwFhv0MjKEym7ZJ8yIT5rxAl7E7OoNj65X95/kkIVK8lIzPkYONL9mMyhBRHoRBhWD1Ir30bKtM4bnOx0IFVm6Q3cyoiwqIADvKOFwtFnLQpN1AuwAOPdOjCQWZoEYfcQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VqaReYkq; 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="VqaReYkq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 032BBC4CEC6; Tue, 15 Oct 2024 12:06:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728994017; bh=nCb9zRnRtsxhqoCJUijrXZAYYIgy7z4yWS8divQUmPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VqaReYkqdMMozH158q9FWywNmr38o4vOZ6rK6UDYtHYwb6DAJur9MhGLDcrXGgwgr rrfqZUW4dOAHZUIdESFc2w3aT6kbqcQ+sCCHN4Z8t6GecUmt90aHyrjEzqpNZ0RhIw zxtJ9JvM7nUDJ41xcggviNXfmQhvhfHCrApbLaMU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christian Schoenebeck , Dominique Martinet , Samasth Norway Ananda Subject: [PATCH 5.15 581/691] 9p: add missing locking around taking dentry fid list Date: Tue, 15 Oct 2024 13:28:49 +0200 Message-ID: <20241015112503.399944215@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015112440.309539031@linuxfoundation.org> References: <20241015112440.309539031@linuxfoundation.org> User-Agent: quilt/0.67 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dominique Martinet commit c898afdc15645efb555acb6d85b484eb40a45409 upstream. Fix a use-after-free on dentry's d_fsdata fid list when a thread looks up a fid through dentry while another thread unlinks it: UAF thread: refcount_t: addition on 0; use-after-free. p9_fid_get linux/./include/net/9p/client.h:262 v9fs_fid_find+0x236/0x280 linux/fs/9p/fid.c:129 v9fs_fid_lookup_with_uid linux/fs/9p/fid.c:181 v9fs_fid_lookup+0xbf/0xc20 linux/fs/9p/fid.c:314 v9fs_vfs_getattr_dotl+0xf9/0x360 linux/fs/9p/vfs_inode_dotl.c:400 vfs_statx+0xdd/0x4d0 linux/fs/stat.c:248 Freed by: p9_fid_destroy (inlined) p9_client_clunk+0xb0/0xe0 linux/net/9p/client.c:1456 p9_fid_put linux/./include/net/9p/client.h:278 v9fs_dentry_release+0xb5/0x140 linux/fs/9p/vfs_dentry.c:55 v9fs_remove+0x38f/0x620 linux/fs/9p/vfs_inode.c:518 vfs_unlink+0x29a/0x810 linux/fs/namei.c:4335 The problem is that d_fsdata was not accessed under d_lock, because d_release() normally is only called once the dentry is otherwise no longer accessible but since we also call it explicitly in v9fs_remove that lock is required: move the hlist out of the dentry under lock then unref its fids once they are no longer accessible. Fixes: 154372e67d40 ("fs/9p: fix create-unlink-getattr idiom") Cc: stable@vger.kernel.org Reported-by: Meysam Firouzi Reported-by: Amirmohammad Eftekhar Reviewed-by: Christian Schoenebeck Message-ID: <20240521122947.1080227-1-asmadeus@codewreck.org> Signed-off-by: Dominique Martinet Signed-off-by: Samasth Norway Ananda Signed-off-by: Greg Kroah-Hartman --- fs/9p/vfs_dentry.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/fs/9p/vfs_dentry.c +++ b/fs/9p/vfs_dentry.c @@ -52,12 +52,17 @@ static int v9fs_cached_dentry_delete(con static void v9fs_dentry_release(struct dentry *dentry) { struct hlist_node *p, *n; + struct hlist_head head; p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n", dentry, dentry); - hlist_for_each_safe(p, n, (struct hlist_head *)&dentry->d_fsdata) + + spin_lock(&dentry->d_lock); + hlist_move_list((struct hlist_head *)&dentry->d_fsdata, &head); + spin_unlock(&dentry->d_lock); + + hlist_for_each_safe(p, n, &head) p9_client_clunk(hlist_entry(p, struct p9_fid, dlist)); - dentry->d_fsdata = NULL; } static int v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)