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 1DB9D1E487 for ; Mon, 8 Jul 2024 13:01:44 +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=1720443705; cv=none; b=As5klDO5wa0QjFdRkfxevNEVuQoscibR++8haDInZGBulpKhmTwJi0z54M4bXCImDRD4RtGe8A12XfDZztdJsD0sByVeOonhgry+yO9Yoxgy6aRL8YVH7TxxF4dLWoXg8Kd9bSI2VpbNdXE862UpA+XTqO0A5J2Zvhnys+Rx3hM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720443705; c=relaxed/simple; bh=/4WCjZczKccBGWquuYp3g0s4W+onyG2WoVqLhFIsgiU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IHDSRzgQHZ3+vsVCgcWSO5oZqo1Bap9luhRclsmoy9H0ru0EZ8U5PO7oc6jy8FwqlWXyz0qK6YZdNh9dhaA92jWMNBHY19hqA/4UE0DWgTx8hs2aCymXnVm33+I3BinzQplfxtqGfYnQaz+MXCbUW5ozpMV24E/g6jyy+5q2I7s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0xAVVLQo; 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="0xAVVLQo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45C7CC32786; Mon, 8 Jul 2024 13:01:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720443704; bh=/4WCjZczKccBGWquuYp3g0s4W+onyG2WoVqLhFIsgiU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=0xAVVLQozQ6RNJNxteXn3BRCT3JeFXjPnTfO54lvgceX1rkddbIXisztfHAW5K2VM 6oCIsw3HzGQcRX4zy8u71RLaDB9NgpRyK8UerNhNCKFYwnyH+X3UA2nEXyuI9AWQGl dGnU17IcHf6yV7xaGg6urn69XsZ1sHD2AD6kibmk= Date: Mon, 8 Jul 2024 15:01:41 +0200 From: Greg KH To: Mimi Zohar Cc: stable@vger.kernel.org, GUO Zihua , casey@schaufler-ca.com, john.johansen@canonical.com, paul@paul-moore.com, Roberto Sassu Subject: Re: [PATCH] ima: Avoid blocking in RCU read-side critical section Message-ID: <2024070828-untaken-depletion-4e4a@gregkh> References: <20240707120439.34700-1-zohar@linux.ibm.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240707120439.34700-1-zohar@linux.ibm.com> On Sun, Jul 07, 2024 at 08:04:39AM -0400, Mimi Zohar wrote: > From: GUO Zihua > > A panic happens in ima_match_policy: > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 > PGD 42f873067 P4D 0 > Oops: 0000 [#1] SMP NOPTI > CPU: 5 PID: 1286325 Comm: kubeletmonit.sh > Kdump: loaded Tainted: P > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 0.0.0 02/06/2015 > RIP: 0010:ima_match_policy+0x84/0x450 > Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39 > 7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d > f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea > 44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f > RSP: 0018:ff71570009e07a80 EFLAGS: 00010207 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200 > RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000 > RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739 > R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970 > R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001 > FS: 00007f5195b51740(0000) > GS:ff3e278b12d40000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ima_get_action+0x22/0x30 > process_measurement+0xb0/0x830 > ? page_add_file_rmap+0x15/0x170 > ? alloc_set_pte+0x269/0x4c0 > ? prep_new_page+0x81/0x140 > ? simple_xattr_get+0x75/0xa0 > ? selinux_file_open+0x9d/0xf0 > ima_file_check+0x64/0x90 > path_openat+0x571/0x1720 > do_filp_open+0x9b/0x110 > ? page_counter_try_charge+0x57/0xc0 > ? files_cgroup_alloc_fd+0x38/0x60 > ? __alloc_fd+0xd4/0x250 > ? do_sys_open+0x1bd/0x250 > do_sys_open+0x1bd/0x250 > do_syscall_64+0x5d/0x1d0 > entry_SYSCALL_64_after_hwframe+0x65/0xca > > Commit c7423dbdbc9e ("ima: Handle -ESTALE returned by > ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a > RCU read-side critical section which contains kmalloc with GFP_KERNEL. > This implies a possible sleep and violates limitations of RCU read-side > critical sections on non-PREEMPT systems. > > Sleeping within RCU read-side critical section might cause > synchronize_rcu() returning early and break RCU protection, allowing a > UAF to happen. > > The root cause of this issue could be described as follows: > | Thread A | Thread B | > | |ima_match_policy | > | | rcu_read_lock | > |ima_lsm_update_rule | | > | synchronize_rcu | | > | | kmalloc(GFP_KERNEL)| > | | sleep | > ==> synchronize_rcu returns early > | kfree(entry) | | > | | entry = entry->next| > ==> UAF happens and entry now becomes NULL (or could be anything). > | | entry->action | > ==> Accessing entry might cause panic. > > To fix this issue, we are converting all kmalloc that is called within > RCU read-side critical section to use GFP_ATOMIC. > > Fixes: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") > Cc: stable@vger.kernel.org > Signed-off-by: GUO Zihua > Acked-by: John Johansen > Reviewed-by: Mimi Zohar > Reviewed-by: Casey Schaufler > [PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case] > Signed-off-by: Paul Moore > (cherry picked from commit 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34) > Signed-off-by: Mimi Zohar > --- > Backport notes: > - Restore default return value parameter to call_int_hook() in > security_audit_rule_init() in lieu of backporting commit 260017f31a8c > ("lsm: use default hook return value in call_int_hook()"). > - Applies to linux-6.8.y -> linux-6.4.y Now applied to 6.6.y, thanks. greg k-h