• Jakub Sitnicki's avatar
    sk_msg: Always cancel strp work before freeing the psock · 1d79895a
    Jakub Sitnicki authored
    Despite having stopped the parser, we still need to deinitialize it
    by calling strp_done so that it cancels its work. Otherwise the worker
    thread can run after we have freed the parser, and attempt to access
    its workqueue resulting in a use-after-free:
    
    ==================================================================
    BUG: KASAN: use-after-free in pwq_activate_delayed_work+0x1b/0x1d0
    Read of size 8 at addr ffff888069975240 by task kworker/u2:2/93
    
    CPU: 0 PID: 93 Comm: kworker/u2:2 Not tainted 5.0.0-rc2-00335-g28f9d1a3-dirty #14
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
    Workqueue:            (null) (kstrp)
    Call Trace:
     print_address_description+0x6e/0x2b0
     ? pwq_activate_delayed_work+0x1b/0x1d0
     kasan_report+0xfd/0x177
     ? pwq_activate_delayed_work+0x1b/0x1d0
     ? pwq_activate_delayed_work+0x1b/0x1d0
     pwq_activate_delayed_work+0x1b/0x1d0
     ? process_one_work+0x4aa/0x660
     pwq_dec_nr_in_flight+0x9b/0x100
     worker_thread+0x82/0x680
     ? process_one_work+0x660/0x660
     kthread+0x1b9/0x1e0
     ? __kthread_create_on_node+0x250/0x250
     ret_from_fork+0x1f/0x30
    
    Allocated by task 111:
     sk_psock_init+0x3c/0x1b0
     sock_map_link.isra.2+0x103/0x4b0
     sock_map_update_common+0x94/0x270
     sock_map_update_elem+0x145/0x160
     __se_sys_bpf+0x152e/0x1e10
     do_syscall_64+0xb2/0x3e0
     entry_SYSCALL_64_after_hwframe+0x44/0xa9
    
    Freed by task 112:
     kfree+0x7f/0x140
     process_one_work+0x40b/0x660
     worker_thread+0x82/0x680
     kthread+0x1b9/0x1e0
     ret_from_fork+0x1f/0x30
    
    The buggy address belongs to the object at ffff888069975180
     which belongs to the cache kmalloc-512 of size 512
    The buggy address is located 192 bytes inside of
     512-byte region [ffff888069975180, ffff888069975380)
    The buggy address belongs to the page:
    page:ffffea0001a65d00 count:1 mapcount:0 mapping:ffff88806d401280 index:0x0 compound_mapcount: 0
    flags: 0x4000000000010200(slab|head)
    raw: 4000000000010200 dead000000000100 dead000000000200 ffff88806d401280
    raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
    page dumped because: kasan: bad access detected
    
    Memory state around the buggy address:
     ffff888069975100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff888069975180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    >ffff888069975200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                               ^
     ffff888069975280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
     ffff888069975300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ==================================================================
    Reported-by: default avatarMarek Majkowski <marek@cloudflare.com>
    Signed-off-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
    Link: https://lore.kernel.org/netdev/CAJPywTLwgXNEZ2dZVoa=udiZmtrWJ0q5SuBW64aYs0Y1khXX3A@mail.gmail.comAcked-by: default avatarSong Liu <songliubraving@fb.com>
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    1d79895a
skmsg.c 18.6 KB