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 901DF1448DA; Thu, 13 Jun 2024 12:07:27 +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=1718280447; cv=none; b=Kfci93KISXa1HsyUZwSz6t5moJiKBRsEceaYGZBc9JBi7G6Lk4IKWgI5y5EDDXMH9Ob480w9gv8CUVoKo+dg1qql5YKWXvgxj/PDy78UX40D1OZiQa+AeYVDMKX3RcJuleL95n7Glt7K3UQuj69+0ZO8Vz5H59+6IXIICmanEKw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718280447; c=relaxed/simple; bh=KZalhTj92n43uRo4jB62ZqxpCiqIisI7kHrlL9OYC5I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kAOjcfj8V3LsAQ06f4H9vwPlDGLYp4JHqDlGVko1I9glKIJ6vBnamG0lWtv5gTOHRqzw1IllLFFlpA2mDU89h6wFaxUaz3+RaG9tbmJ9bt5yvm8r1BpJ0XcK7GEBaamfE49629MsR5JlorxWk2aUe4ztxbV95lkhJWt55xNyAFU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=O1Ts6OZu; 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="O1Ts6OZu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9265C2BBFC; Thu, 13 Jun 2024 12:07:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718280447; bh=KZalhTj92n43uRo4jB62ZqxpCiqIisI7kHrlL9OYC5I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O1Ts6OZuK54eyQe9D9+cAWtPMWwyRkxNENboEOR9ooyp+mZ0lcQRhOkbzd9Fs6g0l W+1zwD8XAW5cSR99EDjSFkCVDjvm9CAE3tF0DNa7DeI6ZasnNI7lNFPiedgheGufGP StLeNO6uBel4f3qh8wkmkKASXOoh4KYYkKcbmJ+c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christian Schoenebeck , Dominique Martinet Subject: [PATCH 6.6 057/137] 9p: add missing locking around taking dentry fid list Date: Thu, 13 Jun 2024 13:33:57 +0200 Message-ID: <20240613113225.514852034@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240613113223.281378087@linuxfoundation.org> References: <20240613113223.281378087@linuxfoundation.org> User-Agent: quilt/0.67 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 6.6-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: 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 @@ -48,12 +48,17 @@ 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_fid_put(hlist_entry(p, struct p9_fid, dlist)); - dentry->d_fsdata = NULL; } static int v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)