• Eric Dumazet's avatar
    ipv6: mcast: fix a use-after-free in inet6_mc_check · ef1cb6b0
    Eric Dumazet authored
    [ Upstream commit dc012f3628eaecfb5ba68404a5c30ef501daf63d ]
    
    syzbot found a use-after-free in inet6_mc_check [1]
    
    The problem here is that inet6_mc_check() uses rcu
    and read_lock(&iml->sflock)
    
    So the fact that ip6_mc_leave_src() is called under RTNL
    and the socket lock does not help us, we need to acquire
    iml->sflock in write mode.
    
    In the future, we should convert all this stuff to RCU.
    
    [1]
    BUG: KASAN: use-after-free in ipv6_addr_equal include/net/ipv6.h:521 [inline]
    BUG: KASAN: use-after-free in inet6_mc_check+0xae7/0xb40 net/ipv6/mcast.c:649
    Read of size 8 at addr ffff8801ce7f2510 by task syz-executor0/22432
    
    CPU: 1 PID: 22432 Comm: syz-executor0 Not tainted 4.19.0-rc7+ #280
    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+0x1c4/0x2b4 lib/dump_stack.c:113
     print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
     kasan_report_error mm/kasan/report.c:354 [inline]
     kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
     __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
     ipv6_addr_equal include/net/ipv6.h:521 [inline]
     inet6_mc_check+0xae7/0xb40 net/ipv6/mcast.c:649
     __raw_v6_lookup+0x320/0x3f0 net/ipv6/raw.c:98
     ipv6_raw_deliver net/ipv6/raw.c:183 [inline]
     raw6_local_deliver+0x3d3/0xcb0 net/ipv6/raw.c:240
     ip6_input_finish+0x467/0x1aa0 net/ipv6/ip6_input.c:345
     NF_HOOK include/linux/netfilter.h:289 [inline]
     ip6_input+0xe9/0x600 net/ipv6/ip6_input.c:426
     ip6_mc_input+0x48a/0xd20 net/ipv6/ip6_input.c:503
     dst_input include/net/dst.h:450 [inline]
     ip6_rcv_finish+0x17a/0x330 net/ipv6/ip6_input.c:76
     NF_HOOK include/linux/netfilter.h:289 [inline]
     ipv6_rcv+0x120/0x640 net/ipv6/ip6_input.c:271
     __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913
     __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023
     netif_receive_skb_internal+0x12c/0x620 net/core/dev.c:5126
     napi_frags_finish net/core/dev.c:5664 [inline]
     napi_gro_frags+0x75a/0xc90 net/core/dev.c:5737
     tun_get_user+0x3189/0x4250 drivers/net/tun.c:1923
     tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1968
     call_write_iter include/linux/fs.h:1808 [inline]
     do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
     do_iter_write+0x185/0x5f0 fs/read_write.c:959
     vfs_writev+0x1f1/0x360 fs/read_write.c:1004
     do_writev+0x11a/0x310 fs/read_write.c:1039
     __do_sys_writev fs/read_write.c:1112 [inline]
     __se_sys_writev fs/read_write.c:1109 [inline]
     __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
     do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x457421
    Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 b5 fb ff c3 48 83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
    RSP: 002b:00007f2d30ecaba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
    RAX: ffffffffffffffda RBX: 000000000000003e RCX: 0000000000457421
    RDX: 0000000000000001 RSI: 00007f2d30ecabf0 RDI: 00000000000000f0
    RBP: 0000000020000500 R08: 00000000000000f0 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000293 R12: 00007f2d30ecb6d4
    R13: 00000000004c4890 R14: 00000000004d7b90 R15: 00000000ffffffff
    
    Allocated by task 22437:
     save_stack+0x43/0xd0 mm/kasan/kasan.c:448
     set_track mm/kasan/kasan.c:460 [inline]
     kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
     __do_kmalloc mm/slab.c:3718 [inline]
     __kmalloc+0x14e/0x760 mm/slab.c:3727
     kmalloc include/linux/slab.h:518 [inline]
     sock_kmalloc+0x15a/0x1f0 net/core/sock.c:1983
     ip6_mc_source+0x14dd/0x1960 net/ipv6/mcast.c:427
     do_ipv6_setsockopt.isra.9+0x3afb/0x45d0 net/ipv6/ipv6_sockglue.c:743
     ipv6_setsockopt+0xbd/0x170 net/ipv6/ipv6_sockglue.c:933
     rawv6_setsockopt+0x59/0x140 net/ipv6/raw.c:1069
     sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3038
     __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
     __do_sys_setsockopt net/socket.c:1913 [inline]
     __se_sys_setsockopt net/socket.c:1910 [inline]
     __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
     do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    Freed by task 22430:
     save_stack+0x43/0xd0 mm/kasan/kasan.c:448
     set_track mm/kasan/kasan.c:460 [inline]
     __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
     kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
     __cache_free mm/slab.c:3498 [inline]
     kfree+0xcf/0x230 mm/slab.c:3813
     __sock_kfree_s net/core/sock.c:2004 [inline]
     sock_kfree_s+0x29/0x60 net/core/sock.c:2010
     ip6_mc_leave_src+0x11a/0x1d0 net/ipv6/mcast.c:2448
     __ipv6_sock_mc_close+0x20b/0x4e0 net/ipv6/mcast.c:310
     ipv6_sock_mc_close+0x158/0x1d0 net/ipv6/mcast.c:328
     inet6_release+0x40/0x70 net/ipv6/af_inet6.c:452
     __sock_release+0xd7/0x250 net/socket.c:579
     sock_close+0x19/0x20 net/socket.c:1141
     __fput+0x385/0xa30 fs/file_table.c:278
     ____fput+0x15/0x20 fs/file_table.c:309
     task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
     tracehook_notify_resume include/linux/tracehook.h:193 [inline]
     exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
     prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
     syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
     do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    The buggy address belongs to the object at ffff8801ce7f2500
     which belongs to the cache kmalloc-192 of size 192
    The buggy address is located 16 bytes inside of
     192-byte region [ffff8801ce7f2500, ffff8801ce7f25c0)
    The buggy address belongs to the page:
    page:ffffea000739fc80 count:1 mapcount:0 mapping:ffff8801da800040 index:0x0
    flags: 0x2fffc0000000100(slab)
    raw: 02fffc0000000100 ffffea0006f6e548 ffffea000737b948 ffff8801da800040
    raw: 0000000000000000 ffff8801ce7f2000 0000000100000010 0000000000000000
    page dumped because: kasan: bad access detected
    
    Memory state around the buggy address:
     ffff8801ce7f2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
     ffff8801ce7f2480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
    >ffff8801ce7f2500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                             ^
     ffff8801ce7f2580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
     ffff8801ce7f2600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    Signed-off-by: 's avatarEric Dumazet <edumazet@google.com>
    Reported-by: 's avatarsyzbot <syzkaller@googlegroups.com>
    Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    ef1cb6b0
mcast.c 69.8 KB