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X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4389 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Eric, On Mon 31 Jan 2022 at 19:20, Eric Dumazet wrote: > From: Eric Dumazet > > 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: > > __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 > > > 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 > Cc: Vlad Buslov > Cc: Jiri Pirko > Cc: Cong Wang > Reported-by: syzbot > --- > net/sched/cls_api.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c > index d4e27c679123f0f62d033c3ad0eeda838e83cb49..5f0f346b576fc0f52a5b8de21758af5425285c2c 100644 > --- a/net/sched/cls_api.c > +++ b/net/sched/cls_api.c > @@ -1945,9 +1945,9 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, > 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; > @@ -1976,6 +1976,8 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, > tp = NULL; > cl = 0; > block = NULL; > + q = NULL; First of all, thanks for fixing this! Maybe it would be better to change __tcf_qdisc_find() to always set q to NULL at the start instead of fixing all users. WDYT? > + chain = NULL; > flags = 0; > > if (prio == 0) { > @@ -2798,8 +2800,8 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n, > struct tcmsg *t; > u32 parent; > u32 chain_index; > - struct Qdisc *q = NULL; > - struct tcf_chain *chain = NULL; > + struct Qdisc *q; > + struct tcf_chain *chain; What is the code path that can reuse old chain value on replay here or in tcf_new_tfilter()? I read the code several times and didn't get it. > struct tcf_block *block; > unsigned long cl; > int err; > @@ -2809,6 +2811,7 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n, > return -EPERM; > > replay: > + q = NULL; > err = nlmsg_parse_deprecated(n, sizeof(*t), tca, TCA_MAX, > rtm_tca_policy, extack); > if (err < 0)