[PATCH 5.4 07/10] net: sched: fix use-after-free in tc_new_tfilter()

From: Greg Kroah-Hartman
Date: Fri Feb 04 2022 - 04:21:08 EST

From: Eric Dumazet <edumazet@xxxxxxxxxx>

commit 04c2a47ffb13c29778e2a14e414ad4cb5a5db4b5 upstream.

Whenever tc_new_tfilter() jumps back to replay: label,
we need to make sure @q and @chain local variables are cleared again,
or risk use-after-free as in [1]

For consistency, apply the same fix in tc_ctl_chain()

BUG: KASAN: use-after-free in mini_qdisc_pair_swap+0x1b9/0x1f0 net/sched/sch_generic.c:1581
Write of size 8 at addr ffff8880985c4b08 by task syz-executor.4/1945

CPU: 0 PID: 1945 Comm: syz-executor.4 Not tainted 5.17.0-rc1-syzkaller-00495-gff58831fa02d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
mini_qdisc_pair_swap+0x1b9/0x1f0 net/sched/sch_generic.c:1581
tcf_chain_head_change_item net/sched/cls_api.c:372 [inline]
tcf_chain0_head_change.isra.0+0xb9/0x120 net/sched/cls_api.c:386
tcf_chain_tp_insert net/sched/cls_api.c:1657 [inline]
tcf_chain_tp_insert_unique net/sched/cls_api.c:1707 [inline]
tc_new_tfilter+0x1e67/0x2350 net/sched/cls_api.c:2086
rtnetlink_rcv_msg+0x80d/0xb80 net/core/rtnetlink.c:5583
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x539/0x7e0 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:725
____sys_sendmsg+0x331/0x810 net/socket.c:2413
___sys_sendmsg+0xf3/0x170 net/socket.c:2467
__sys_sendmmsg+0x195/0x470 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2579
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
RIP: 0033:0x7f2647172059
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2645aa5168 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f2647285100 RCX: 00007f2647172059
RDX: 040000000000009f RSI: 00000000200002c0 RDI: 0000000000000006
RBP: 00007f26471cc08d R08: 0000000000000000 R09: 0000000000000000
R10: 9e00000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffb3f7f02f R14: 00007f2645aa5300 R15: 0000000000022000
</TASK>

Allocated by task 1944:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
kmalloc_node include/linux/slab.h:604 [inline]
kzalloc_node include/linux/slab.h:726 [inline]
qdisc_alloc+0xac/0xa10 net/sched/sch_generic.c:941
qdisc_create.constprop.0+0xce/0x10f0 net/sched/sch_api.c:1211
tc_modify_qdisc+0x4c5/0x1980 net/sched/sch_api.c:1660
rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5592
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x539/0x7e0 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:725
____sys_sendmsg+0x331/0x810 net/socket.c:2413
___sys_sendmsg+0xf3/0x170 net/socket.c:2467
__sys_sendmmsg+0x195/0x470 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2579
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

Freed by task 3609:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:236 [inline]
slab_free_hook mm/slub.c:1728 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754
slab_free mm/slub.c:3509 [inline]
kfree+0xcb/0x280 mm/slub.c:4562
rcu_do_batch kernel/rcu/tree.c:2527 [inline]
rcu_core+0x7b8/0x1540 kernel/rcu/tree.c:2778
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558

Last potentially related work creation:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
__kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
__call_rcu kernel/rcu/tree.c:3026 [inline]
call_rcu+0xb1/0x740 kernel/rcu/tree.c:3106
qdisc_put_unlocked+0x6f/0x90 net/sched/sch_generic.c:1109
tcf_block_release+0x86/0x90 net/sched/cls_api.c:1238
tc_new_tfilter+0xc0d/0x2350 net/sched/cls_api.c:2148
rtnetlink_rcv_msg+0x80d/0xb80 net/core/rtnetlink.c:5583
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x539/0x7e0 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:725
____sys_sendmsg+0x331/0x810 net/socket.c:2413
___sys_sendmsg+0xf3/0x170 net/socket.c:2467
__sys_sendmmsg+0x195/0x470 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2579
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

The buggy address belongs to the object at ffff8880985c4800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 776 bytes inside of
1024-byte region [ffff8880985c4800, ffff8880985c4c00)
The buggy address belongs to the page:
page:ffffea0002617000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x985c0
head:ffffea0002617000 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888010c41dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 1941, ts 1038999441284, free_ts 1033444432829
prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
alloc_slab_page mm/slub.c:1799 [inline]
allocate_slab mm/slub.c:1944 [inline]
new_slab+0x28a/0x3b0 mm/slub.c:2004
___slab_alloc+0x87c/0xe90 mm/slub.c:3018
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105
slab_alloc_node mm/slub.c:3196 [inline]
slab_alloc mm/slub.c:3238 [inline]
__kmalloc+0x2fb/0x340 mm/slub.c:4420
kmalloc include/linux/slab.h:586 [inline]
kzalloc include/linux/slab.h:715 [inline]
__register_sysctl_table+0x112/0x1090 fs/proc/proc_sysctl.c:1335
neigh_sysctl_register+0x2c8/0x5e0 net/core/neighbour.c:3787
devinet_sysctl_register+0xb1/0x230 net/ipv4/devinet.c:2618
inetdev_init+0x286/0x580 net/ipv4/devinet.c:278
inetdev_event+0xa8a/0x15d0 net/ipv4/devinet.c:1532
notifier_call_chain+0xb5/0x200 kernel/notifier.c:84
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1919
call_netdevice_notifiers_extack net/core/dev.c:1931 [inline]
call_netdevice_notifiers net/core/dev.c:1945 [inline]
register_netdevice+0x1073/0x1500 net/core/dev.c:9698
veth_newlink+0x59c/0xa90 drivers/net/veth.c:1722
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1352 [inline]
free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
free_unref_page_prepare mm/page_alloc.c:3325 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3404
release_pages+0x748/0x1220 mm/swap.c:956
tlb_batch_pages_flush mm/mmu_gather.c:50 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:243 [inline]
tlb_flush_mmu+0xe9/0x6b0 mm/mmu_gather.c:250
zap_pte_range mm/memory.c:1441 [inline]
zap_pmd_range mm/memory.c:1490 [inline]
zap_pud_range mm/memory.c:1519 [inline]
zap_p4d_range mm/memory.c:1540 [inline]
unmap_page_range+0x1d1d/0x2a30 mm/memory.c:1561
unmap_single_vma+0x198/0x310 mm/memory.c:1606
unmap_vmas+0x16b/0x2f0 mm/memory.c:1638
exit_mmap+0x201/0x670 mm/mmap.c:3178
__mmput+0x122/0x4b0 kernel/fork.c:1114
mmput+0x56/0x60 kernel/fork.c:1135
exit_mm kernel/exit.c:507 [inline]
do_exit+0xa3c/0x2a30 kernel/exit.c:793
do_group_exit+0xd2/0x2f0 kernel/exit.c:935
__do_sys_exit_group kernel/exit.c:946 [inline]
__se_sys_exit_group kernel/exit.c:944 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
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

Memory state around the buggy address:
ffff8880985c4a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880985c4a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880985c4b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880985c4b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880985c4c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Fixes: 470502de5bdb ("net: sched: unlock rules update API")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Vlad Buslov <vladbu@xxxxxxxxxxxx>
Cc: Jiri Pirko <jiri@xxxxxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220131172018.3704490-1-eric.dumazet@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/cls_api.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1928,9 +1928,9 @@ static int tc_new_tfilter(struct sk_buff
bool prio_allocate;
u32 parent;
u32 chain_index;
- struct Qdisc *q = NULL;
+ struct Qdisc *q;
struct tcf_chain_info chain_info;
- struct tcf_chain *chain = NULL;
+ struct tcf_chain *chain;
struct tcf_block *block;
struct tcf_proto *tp;
unsigned long cl;
@@ -1958,6 +1958,8 @@ replay:
tp = NULL;
cl = 0;
block = NULL;
+ q = NULL;
+ chain = NULL;

if (prio == 0) {
/* If no priority is provided by the user,
@@ -2764,8 +2766,8 @@ static int tc_ctl_chain(struct sk_buff *
struct tcmsg *t;
u32 parent;
u32 chain_index;
- struct Qdisc *q = NULL;
- struct tcf_chain *chain = NULL;
+ struct Qdisc *q;
+ struct tcf_chain *chain;
struct tcf_block *block;
unsigned long cl;
int err;
@@ -2775,6 +2777,7 @@ static int tc_ctl_chain(struct sk_buff *
return -EPERM;

replay:
+ q = NULL;
err = nlmsg_parse_deprecated(n, sizeof(*t), tca, TCA_MAX,
rtm_tca_policy, extack);
if (err < 0)