Re: [syzbot] [net?] KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings

[syzbot <syzbot+5fe14f2ff4ccbace9a26@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in __ethtool_get_link_ksettings

==================================================================
BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x6e/0x190 net/ethtool/ioctl.c:442
Read of size 8 at addr ffff88805df9e308 by task kworker/0:0/8

CPU: 0 UID: 0 PID: 8 Comm: kworker/0:0 Not tainted 6.12.0-rc2-syzkaller-00002-g615b94746a54-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events smc_ib_port_event_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 __ethtool_get_link_ksettings+0x6e/0x190 net/ethtool/ioctl.c:442
 ib_get_eth_speed+0x160/0x800 drivers/infiniband/core/verbs.c:1996
 rxe_query_port+0x76/0x260 drivers/infiniband/sw/rxe/rxe_verbs.c:55
 __ib_query_port drivers/infiniband/core/device.c:2105 [inline]
 ib_query_port+0x208/0x870 drivers/infiniband/core/device.c:2147
 smc_ib_remember_port_attr net/smc/smc_ib.c:364 [inline]
 smc_ib_port_event_work+0x14e/0xa50 net/smc/smc_ib.c:388
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 5966:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:257 [inline]
 __do_kmalloc_node mm/slub.c:4264 [inline]
 __kmalloc_node_noprof+0x22a/0x440 mm/slub.c:4270
 __kvmalloc_node_noprof+0x72/0x190 mm/util.c:658
 alloc_netdev_mqs+0x9b/0x1000 net/core/dev.c:11097
 rtnl_create_link+0x2f9/0xc20 net/core/rtnetlink.c:3374
 rtnl_newlink_create net/core/rtnetlink.c:3500 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3730 [inline]
 rtnl_newlink+0x1423/0x20a0 net/core/rtnetlink.c:3743
 rtnetlink_rcv_msg+0x73f/0xcf0 net/core/rtnetlink.c:6646
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357
 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:729 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:744
 __sys_sendto+0x39b/0x4f0 net/socket.c:2209
 __do_sys_sendto net/socket.c:2221 [inline]
 __se_sys_sendto net/socket.c:2217 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2217
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 64:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:2342 [inline]
 slab_free mm/slub.c:4579 [inline]
 kfree+0x1a0/0x440 mm/slub.c:4727
 device_release+0x99/0x1c0
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22f/0x480 lib/kobject.c:737
 netdev_run_todo+0xe79/0x1000 net/core/dev.c:10816
 default_device_exit_batch+0xa24/0xaa0 net/core/dev.c:11949
 ops_exit_list net/core/net_namespace.c:178 [inline]
 cleanup_net+0x89d/0xcc0 net/core/net_namespace.c:626
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff88805df9e000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 776 bytes inside of
 freed 4096-byte region [ffff88805df9e000, ffff88805df9f000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5df98
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888028f67841
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801ac4f500 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000001f5000000 ffff888028f67841
head: 00fff00000000040 ffff88801ac4f500 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000001f5000000 ffff888028f67841
head: 00fff00000000003 ffffea000177e601 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5966, tgid 5966 (syz-executor), ts 106703177356, free_ts 104254916301
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1545 [inline]
 get_page_from_freelist+0x3045/0x3190 mm/page_alloc.c:3457
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4733
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 alloc_slab_page+0x6a/0x120 mm/slub.c:2412
 allocate_slab+0x5a/0x2f0 mm/slub.c:2578
 new_slab mm/slub.c:2631 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3818
 __slab_alloc+0x58/0xa0 mm/slub.c:3908
 __slab_alloc_node mm/slub.c:3961 [inline]
 slab_alloc_node mm/slub.c:4122 [inline]
 __kmalloc_cache_noprof+0x1d5/0x2c0 mm/slub.c:4290
 kmalloc_noprof include/linux/slab.h:878 [inline]
 kzalloc_noprof include/linux/slab.h:1014 [inline]
 snmp6_alloc_dev net/ipv6/addrconf.c:359 [inline]
 ipv6_add_dev+0x570/0x1220 net/ipv6/addrconf.c:409
 addrconf_notify+0x6a7/0x1020 net/ipv6/addrconf.c:3655
 notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2034 [inline]
 call_netdevice_notifiers net/core/dev.c:2048 [inline]
 register_netdevice+0x167f/0x1b00 net/core/dev.c:10524
 virt_wifi_newlink+0x3ba/0x7c0 drivers/net/wireless/virtual/virt_wifi.c:567
 rtnl_newlink_create net/core/rtnetlink.c:3510 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3730 [inline]
 rtnl_newlink+0x1591/0x20a0 net/core/rtnetlink.c:3743
 rtnetlink_rcv_msg+0x73f/0xcf0 net/core/rtnetlink.c:6646
page last free pid 5937 tgid 5937 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1108 [inline]
 free_unref_page+0xcfb/0xf20 mm/page_alloc.c:2638
 vfree+0x186/0x2e0 mm/vmalloc.c:3361
 kcov_put kernel/kcov.c:439 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:535
 __fput+0x23f/0x880 fs/file_table.c:431
 task_work_run+0x24f/0x310 kernel/task_work.c:228
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xa2f/0x28e0 kernel/exit.c:939
 do_group_exit+0x207/0x2c0 kernel/exit.c:1088
 get_signal+0x16a3/0x1740 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88805df9e200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805df9e280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805df9e300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88805df9e380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805df9e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         615b9474 RDMA/hns: Disassociate mmap pages for all uct..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
console output: https://syzkaller.appspot.com/x/log.txt?x=138f0727980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7cd9e7e4a8a0a15b
dashboard link: https://syzkaller.appspot.com/bug?extid=5fe14f2ff4ccbace9a26
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=117a4440580000