From: Taehee Yoo ap420073@gmail.com
[ Upstream commit 9b76eade16423ef06829cccfe3e100cfce31afcd ]
If Qdisc_ops->init() is failed, Qdisc_ops->reset() would be called. When dsmark_init(Qdisc_ops->init()) is failed, it possibly doesn't initialize dsmark_qdisc_data->q. But dsmark_reset(Qdisc_ops->reset()) uses dsmark_qdisc_data->q pointer wihtout any null checking. So, panic would occur.
Test commands: sysctl net.core.default_qdisc=dsmark -w ip link add dummy0 type dummy ip link add vw0 link dummy0 type virt_wifi ip link set vw0 up
Splat looks like: KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] CPU: 3 PID: 684 Comm: ip Not tainted 5.12.0+ #910 RIP: 0010:qdisc_reset+0x2b/0x680 Code: 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 41 57 41 56 41 55 41 54 55 48 89 fd 48 83 c7 18 53 48 89 fa 48 c1 ea 03 48 83 ec 20 <80> 3c 02 00 0f 85 09 06 00 00 4c 8b 65 18 0f 1f 44 00 00 65 8b 1d RSP: 0018:ffff88800fda6bf8 EFLAGS: 00010282 RAX: dffffc0000000000 RBX: ffff8880050ed800 RCX: 0000000000000000 RDX: 0000000000000003 RSI: ffffffff99e34100 RDI: 0000000000000018 RBP: 0000000000000000 R08: fffffbfff346b553 R09: fffffbfff346b553 R10: 0000000000000001 R11: fffffbfff346b552 R12: ffffffffc0824940 R13: ffff888109e83800 R14: 00000000ffffffff R15: ffffffffc08249e0 FS: 00007f5042287680(0000) GS:ffff888119800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055ae1f4dbd90 CR3: 0000000006760002 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? rcu_read_lock_bh_held+0xa0/0xa0 dsmark_reset+0x3d/0xf0 [sch_dsmark] qdisc_reset+0xa9/0x680 qdisc_destroy+0x84/0x370 qdisc_create_dflt+0x1fe/0x380 attach_one_default_qdisc.constprop.41+0xa4/0x180 dev_activate+0x4d5/0x8c0 ? __dev_open+0x268/0x390 __dev_open+0x270/0x390
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Taehee Yoo ap420073@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/sched/sch_dsmark.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c index b507a72d5813..b972d50828ca 100644 --- a/net/sched/sch_dsmark.c +++ b/net/sched/sch_dsmark.c @@ -397,7 +397,8 @@ static void dsmark_reset(struct Qdisc *sch) struct dsmark_qdisc_data *p = qdisc_priv(sch);
pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p); - qdisc_reset(p->q); + if (p->q) + qdisc_reset(p->q); sch->qstats.backlog = 0; sch->q.qlen = 0; }