| From 9846da773afe33332590b188563b1a58e89b5e32 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 30 Sep 2021 14:22:39 -0700 |
| Subject: net_sched: fix NULL deref in fifo_set_limit() |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| [ Upstream commit 560ee196fe9e5037e5015e2cdb14b3aecb1cd7dc ] |
| |
| syzbot reported another NULL deref in fifo_set_limit() [1] |
| |
| I could repro the issue with : |
| |
| unshare -n |
| tc qd add dev lo root handle 1:0 tbf limit 200000 burst 70000 rate 100Mbit |
| tc qd replace dev lo parent 1:0 pfifo_fast |
| tc qd change dev lo root handle 1:0 tbf limit 300000 burst 70000 rate 100Mbit |
| |
| pfifo_fast does not have a change() operation. |
| Make fifo_set_limit() more robust about this. |
| |
| [1] |
| BUG: kernel NULL pointer dereference, address: 0000000000000000 |
| PGD 1cf99067 P4D 1cf99067 PUD 7ca49067 PMD 0 |
| Oops: 0010 [#1] PREEMPT SMP KASAN |
| CPU: 1 PID: 14443 Comm: syz-executor959 Not tainted 5.15.0-rc3-syzkaller #0 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 |
| RIP: 0010:0x0 |
| Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. |
| RSP: 0018:ffffc9000e2f7310 EFLAGS: 00010246 |
| RAX: dffffc0000000000 RBX: ffffffff8d6ecc00 RCX: 0000000000000000 |
| RDX: 0000000000000000 RSI: ffff888024c27910 RDI: ffff888071e34000 |
| RBP: ffff888071e34000 R08: 0000000000000001 R09: ffffffff8fcfb947 |
| R10: 0000000000000001 R11: 0000000000000000 R12: ffff888024c27910 |
| R13: ffff888071e34018 R14: 0000000000000000 R15: ffff88801ef74800 |
| FS: 00007f321d897700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: ffffffffffffffd6 CR3: 00000000722c3000 CR4: 00000000003506e0 |
| DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| Call Trace: |
| fifo_set_limit net/sched/sch_fifo.c:242 [inline] |
| fifo_set_limit+0x198/0x210 net/sched/sch_fifo.c:227 |
| tbf_change+0x6ec/0x16d0 net/sched/sch_tbf.c:418 |
| qdisc_change net/sched/sch_api.c:1332 [inline] |
| tc_modify_qdisc+0xd9a/0x1a60 net/sched/sch_api.c:1634 |
| rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5572 |
| netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504 |
| netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] |
| netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340 |
| netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929 |
| sock_sendmsg_nosec net/socket.c:704 [inline] |
| sock_sendmsg+0xcf/0x120 net/socket.c:724 |
| ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409 |
| ___sys_sendmsg+0xf3/0x170 net/socket.c:2463 |
| __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492 |
| do_syscall_x64 arch/x86/entry/common.c:50 [inline] |
| do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 |
| entry_SYSCALL_64_after_hwframe+0x44/0xae |
| |
| Fixes: fb0305ce1b03 ("net-sched: consolidate default fifo qdisc setup") |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Reported-by: syzbot <syzkaller@googlegroups.com> |
| Link: https://lore.kernel.org/r/20210930212239.3430364-1-eric.dumazet@gmail.com |
| Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| net/sched/sch_fifo.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c |
| index 24893d3b5d22..bcd3ca97caea 100644 |
| --- a/net/sched/sch_fifo.c |
| +++ b/net/sched/sch_fifo.c |
| @@ -152,6 +152,9 @@ int fifo_set_limit(struct Qdisc *q, unsigned int limit) |
| if (strncmp(q->ops->id + 1, "fifo", 4) != 0) |
| return 0; |
| |
| + if (!q->ops->change) |
| + return 0; |
| + |
| nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); |
| if (nla) { |
| nla->nla_type = RTM_NEWQDISC; |
| -- |
| 2.33.0 |
| |