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X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB2401 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon 31 Jan 2022 at 21:08, Eric Dumazet wrote: > On Mon, Jan 31, 2022 at 10:53 AM Vlad Buslov wrote: >> >> 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? > > I guess that would be another way to fix the issue. > > But the patch seemed a bit more invasive and not really to review. > Okay, no problem. > >> >> > + 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. > > As explained in the changelog, it is done for consistency with the > other function > doing this dangerous replay stuff. > Yeah, but I also didn't get how the "chain" variable can get reused in that other function (tcf_new_tfilter()). It seems to always be unconditionally assigned with return value of tcf_chain_get(). > People are very often copying/pasting code. > > >> >> > 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) >>