lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Sun, 16 Aug 2020 17:31:48 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     akpm@...ux-foundation.org
Cc:     oleg@...hat.com, axboe@...nel.dk, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dave@...olabs.net>,
        Greg Thelen <gthelen@...gle.com>,
        Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 2/2] block: fix ioprio_get/set(IOPRIO_WHO_PGRP) vs setuid(2)

do_each_pid_thread(PIDTYPE_PGID) can race with a concurrent
change_pid(PIDTYPE_PGID) that can move the task from one hlist
to another while iterating. Serialize ioprio_get/set to take
the tasklist_lock in this case.

Fixes: d69b78ba1de (ioprio: grab rcu_read_lock in sys_ioprio_{set,get}())
Cc: Greg Thelen <gthelen@...gle.com>
Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 block/ioprio.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/ioprio.c b/block/ioprio.c
index 77bcab11dce5..4ede2da961bb 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -119,11 +119,13 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
 				pgrp = task_pgrp(current);
 			else
 				pgrp = find_vpid(who);
+			read_lock(&tasklist_lock);
 			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
 				ret = set_task_ioprio(p, ioprio);
 				if (ret)
 					break;
 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
+			read_unlock(&tasklist_lock);
 			break;
 		case IOPRIO_WHO_USER:
 			uid = make_kuid(current_user_ns(), who);
@@ -207,6 +209,7 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
 				pgrp = task_pgrp(current);
 			else
 				pgrp = find_vpid(who);
+			read_lock(&tasklist_lock);
 			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
 				tmpio = get_task_ioprio(p);
 				if (tmpio < 0)
@@ -216,6 +219,7 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
 				else
 					ret = ioprio_best(ret, tmpio);
 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
+			read_unlock(&tasklist_lock);
 			break;
 		case IOPRIO_WHO_USER:
 			uid = make_kuid(current_user_ns(), who);
-- 
2.26.2

Powered by blists - more mailing lists