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Message-ID: <20240904120842.3426084-2-dmantipov@yandex.ru>
Date: Wed, 4 Sep 2024 15:08:42 +0300
From: Dmitry Antipov <dmantipov@...dex.ru>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>
Cc: Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Simon Horman <horms@...nel.org>,
netdev@...r.kernel.org,
lvc-project@...uxtesting.org,
Dmitry Antipov <dmantipov@...dex.ru>
Subject: [PATCH net v5 2/2] net: sched: use RCU read-side critical section in taprio_dump()
Fix possible use-after-free in 'taprio_dump()' by adding RCU
read-side critical section there. Never seen on x86 but
found on a KASAN-enabled arm64 system when investigating
https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa:
[T15862] BUG: KASAN: slab-use-after-free in taprio_dump+0xa0c/0xbb0
[T15862] Read of size 4 at addr ffff0000d4bb88f8 by task repro/15862
[T15862]
[T15862] CPU: 0 UID: 0 PID: 15862 Comm: repro Not tainted 6.11.0-rc1-00293-gdefaf1a2113a-dirty #2
[T15862] Hardware name: QEMU QEMU Virtual Machine, BIOS edk2-20240524-5.fc40 05/24/2024
[T15862] Call trace:
[T15862] dump_backtrace+0x20c/0x220
[T15862] show_stack+0x2c/0x40
[T15862] dump_stack_lvl+0xf8/0x174
[T15862] print_report+0x170/0x4d8
[T15862] kasan_report+0xb8/0x1d4
[T15862] __asan_report_load4_noabort+0x20/0x2c
[T15862] taprio_dump+0xa0c/0xbb0
[T15862] tc_fill_qdisc+0x540/0x1020
[T15862] qdisc_notify.isra.0+0x330/0x3a0
[T15862] tc_modify_qdisc+0x7b8/0x1838
[T15862] rtnetlink_rcv_msg+0x3c8/0xc20
[T15862] netlink_rcv_skb+0x1f8/0x3d4
[T15862] rtnetlink_rcv+0x28/0x40
[T15862] netlink_unicast+0x51c/0x790
[T15862] netlink_sendmsg+0x79c/0xc20
[T15862] __sock_sendmsg+0xe0/0x1a0
[T15862] ____sys_sendmsg+0x6c0/0x840
[T15862] ___sys_sendmsg+0x1ac/0x1f0
[T15862] __sys_sendmsg+0x110/0x1d0
[T15862] __arm64_sys_sendmsg+0x74/0xb0
[T15862] invoke_syscall+0x88/0x2e0
[T15862] el0_svc_common.constprop.0+0xe4/0x2a0
[T15862] do_el0_svc+0x44/0x60
[T15862] el0_svc+0x50/0x184
[T15862] el0t_64_sync_handler+0x120/0x12c
[T15862] el0t_64_sync+0x190/0x194
[T15862]
[T15862] Allocated by task 15857:
[T15862] kasan_save_stack+0x3c/0x70
[T15862] kasan_save_track+0x20/0x3c
[T15862] kasan_save_alloc_info+0x40/0x60
[T15862] __kasan_kmalloc+0xd4/0xe0
[T15862] __kmalloc_cache_noprof+0x194/0x334
[T15862] taprio_change+0x45c/0x2fe0
[T15862] tc_modify_qdisc+0x6a8/0x1838
[T15862] rtnetlink_rcv_msg+0x3c8/0xc20
[T15862] netlink_rcv_skb+0x1f8/0x3d4
[T15862] rtnetlink_rcv+0x28/0x40
[T15862] netlink_unicast+0x51c/0x790
[T15862] netlink_sendmsg+0x79c/0xc20
[T15862] __sock_sendmsg+0xe0/0x1a0
[T15862] ____sys_sendmsg+0x6c0/0x840
[T15862] ___sys_sendmsg+0x1ac/0x1f0
[T15862] __sys_sendmsg+0x110/0x1d0
[T15862] __arm64_sys_sendmsg+0x74/0xb0
[T15862] invoke_syscall+0x88/0x2e0
[T15862] el0_svc_common.constprop.0+0xe4/0x2a0
[T15862] do_el0_svc+0x44/0x60
[T15862] el0_svc+0x50/0x184
[T15862] el0t_64_sync_handler+0x120/0x12c
[T15862] el0t_64_sync+0x190/0x194
[T15862]
[T15862] Freed by task 6192:
[T15862] kasan_save_stack+0x3c/0x70
[T15862] kasan_save_track+0x20/0x3c
[T15862] kasan_save_free_info+0x4c/0x80
[T15862] poison_slab_object+0x110/0x160
[T15862] __kasan_slab_free+0x3c/0x74
[T15862] kfree+0x134/0x3c0
[T15862] taprio_free_sched_cb+0x18c/0x220
[T15862] rcu_core+0x920/0x1b7c
[T15862] rcu_core_si+0x10/0x1c
[T15862] handle_softirqs+0x2e8/0xd64
[T15862] __do_softirq+0x14/0x20
Fixes: 18cdd2f0998a ("net/sched: taprio: taprio_dump and taprio_change are protected by rtnl_mutex")
Signed-off-by: Dmitry Antipov <dmantipov@...dex.ru>
---
v5: add Fixes: and resend due to series change
v4: redesign to preserve original code as much as possible,
adjust commit message and subject to target net tree
v3: tweak commit message as suggested by Vinicius
v2: added to the series
---
net/sched/sch_taprio.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 59fad74d5ff9..522eec6f92d1 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2372,9 +2372,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
struct tc_mqprio_qopt opt = { 0 };
struct nlattr *nest, *sched_nest;
- oper = rtnl_dereference(q->oper_sched);
- admin = rtnl_dereference(q->admin_sched);
-
mqprio_qopt_reconstruct(dev, &opt);
nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
@@ -2395,18 +2392,23 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_put_u32(skb, TCA_TAPRIO_ATTR_TXTIME_DELAY, q->txtime_delay))
goto options_error;
+ rcu_read_lock();
+
+ oper = rtnl_dereference(q->oper_sched);
+ admin = rtnl_dereference(q->admin_sched);
+
if (oper && taprio_dump_tc_entries(skb, q, oper))
- goto options_error;
+ goto options_error_rcu;
if (oper && dump_schedule(skb, oper))
- goto options_error;
+ goto options_error_rcu;
if (!admin)
goto done;
sched_nest = nla_nest_start_noflag(skb, TCA_TAPRIO_ATTR_ADMIN_SCHED);
if (!sched_nest)
- goto options_error;
+ goto options_error_rcu;
if (dump_schedule(skb, admin))
goto admin_error;
@@ -2414,11 +2416,15 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_nest_end(skb, sched_nest);
done:
+ rcu_read_unlock();
return nla_nest_end(skb, nest);
admin_error:
nla_nest_cancel(skb, sched_nest);
+options_error_rcu:
+ rcu_read_unlock();
+
options_error:
nla_nest_cancel(skb, nest);
--
2.46.0
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