• Eric Dumazet's avatar
    net/x25: fix use-after-free in x25_device_event() · 95d6ebd5
    Eric Dumazet authored
    In case of failure x25_connect() does a x25_neigh_put(x25->neighbour)
    but forgets to clear x25->neighbour pointer, thus triggering use-after-free.
    
    Since the socket is visible in x25_list, we need to hold x25_list_lock
    to protect the operation.
    
    syzbot report :
    
    BUG: KASAN: use-after-free in x25_kill_by_device net/x25/af_x25.c:217 [inline]
    BUG: KASAN: use-after-free in x25_device_event+0x296/0x2b0 net/x25/af_x25.c:252
    Read of size 8 at addr ffff8880a030edd0 by task syz-executor003/7854
    
    CPU: 0 PID: 7854 Comm: syz-executor003 Not tainted 5.0.0+ #97
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
     __dump_stack lib/dump_stack.c:77 [inline]
     dump_stack+0x172/0x1f0 lib/dump_stack.c:113
     print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
     kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
     __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
     x25_kill_by_device net/x25/af_x25.c:217 [inline]
     x25_device_event+0x296/0x2b0 net/x25/af_x25.c:252
     notifier_call_chain+0xc7/0x240 kernel/notifier.c:93
     __raw_notifier_call_chain kernel/notifier.c:394 [inline]
     raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:401
     call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1739
     call_netdevice_notifiers_extack net/core/dev.c:1751 [inline]
     call_netdevice_notifiers net/core/dev.c:1765 [inline]
     __dev_notify_flags+0x1e9/0x2c0 net/core/dev.c:7607
     dev_change_flags+0x10d/0x170 net/core/dev.c:7643
     dev_ifsioc+0x2b0/0x940 net/core/dev_ioctl.c:237
     dev_ioctl+0x1b8/0xc70 net/core/dev_ioctl.c:488
     sock_do_ioctl+0x1bd/0x300 net/socket.c:995
     sock_ioctl+0x32b/0x610 net/socket.c:1096
     vfs_ioctl fs/ioctl.c:46 [inline]
     file_ioctl fs/ioctl.c:509 [inline]
     do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
     ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
     __do_sys_ioctl fs/ioctl.c:720 [inline]
     __se_sys_ioctl fs/ioctl.c:718 [inline]
     __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
     do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x4467c9
    Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 5b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00
    RSP: 002b:00007fdbea222d98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
    RAX: ffffffffffffffda RBX: 00000000006dbc58 RCX: 00000000004467c9
    RDX: 0000000020000340 RSI: 0000000000008914 RDI: 0000000000000003
    RBP: 00000000006dbc50 R08: 00007fdbea223700 R09: 0000000000000000
    R10: 00007fdbea223700 R11: 0000000000000246 R12: 00000000006dbc5c
    R13: 6000030030626669 R14: 0000000000000000 R15: 0000000030626669
    
    Allocated by task 7843:
     save_stack+0x45/0xd0 mm/kasan/common.c:73
     set_track mm/kasan/common.c:85 [inline]
     __kasan_kmalloc mm/kasan/common.c:495 [inline]
     __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:468
     kasan_kmalloc+0x9/0x10 mm/kasan/common.c:509
     kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3615
     kmalloc include/linux/slab.h:545 [inline]
     x25_link_device_up+0x46/0x3f0 net/x25/x25_link.c:249
     x25_device_event+0x116/0x2b0 net/x25/af_x25.c:242
     notifier_call_chain+0xc7/0x240 kernel/notifier.c:93
     __raw_notifier_call_chain kernel/notifier.c:394 [inline]
     raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:401
     call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1739
     call_netdevice_notifiers_extack net/core/dev.c:1751 [inline]
     call_netdevice_notifiers net/core/dev.c:1765 [inline]
     __dev_notify_flags+0x121/0x2c0 net/core/dev.c:7605
     dev_change_flags+0x10d/0x170 net/core/dev.c:7643
     dev_ifsioc+0x2b0/0x940 net/core/dev_ioctl.c:237
     dev_ioctl+0x1b8/0xc70 net/core/dev_ioctl.c:488
     sock_do_ioctl+0x1bd/0x300 net/socket.c:995
     sock_ioctl+0x32b/0x610 net/socket.c:1096
     vfs_ioctl fs/ioctl.c:46 [inline]
     file_ioctl fs/ioctl.c:509 [inline]
     do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
     ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
     __do_sys_ioctl fs/ioctl.c:720 [inline]
     __se_sys_ioctl fs/ioctl.c:718 [inline]
     __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
     do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    Freed by task 7865:
     save_stack+0x45/0xd0 mm/kasan/common.c:73
     set_track mm/kasan/common.c:85 [inline]
     __kasan_slab_free+0x102/0x150 mm/kasan/common.c:457
     kasan_slab_free+0xe/0x10 mm/kasan/common.c:465
     __cache_free mm/slab.c:3494 [inline]
     kfree+0xcf/0x230 mm/slab.c:3811
     x25_neigh_put include/net/x25.h:253 [inline]
     x25_connect+0x8d8/0xde0 net/x25/af_x25.c:824
     __sys_connect+0x266/0x330 net/socket.c:1685
     __do_sys_connect net/socket.c:1696 [inline]
     __se_sys_connect net/socket.c:1693 [inline]
     __x64_sys_connect+0x73/0xb0 net/socket.c:1693
     do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    The buggy address belongs to the object at ffff8880a030edc0
     which belongs to the cache kmalloc-256 of size 256
    The buggy address is located 16 bytes inside of
     256-byte region [ffff8880a030edc0, ffff8880a030eec0)
    The buggy address belongs to the page:
    page:ffffea000280c380 count:1 mapcount:0 mapping:ffff88812c3f07c0 index:0x0
    flags: 0x1fffc0000000200(slab)
    raw: 01fffc0000000200 ffffea0002806788 ffffea00027f0188 ffff88812c3f07c0
    raw: 0000000000000000 ffff8880a030e000 000000010000000c 0000000000000000
    page dumped because: kasan: bad access detected
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Reported-by: syzbot+04babcefcd396fabec37@syzkaller.appspotmail.com
    Cc: andrew hendry <andrew.hendry@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    95d6ebd5
af_x25.c 40.5 KB