• Eric Dumazet's avatar
    tun: napi flags belong to tfile · af3fb24e
    Eric Dumazet authored
    Since tun->flags might be shared by multiple tfile structures,
    it is better to make sure tun_get_user() is using the flags
    for the current tfile.
    
    Presence of the READ_ONCE() in tun_napi_frags_enabled() gave a hint
    of what could happen, but we need something stronger to please
    syzbot.
    
    kasan: CONFIG_KASAN_INLINE enabled
    kasan: GPF could be caused by NULL-ptr deref or user memory access
    general protection fault: 0000 [#1] PREEMPT SMP KASAN
    CPU: 0 PID: 13647 Comm: syz-executor5 Not tainted 4.19.0-rc5+ #59
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    RIP: 0010:dev_gro_receive+0x132/0x2720 net/core/dev.c:5427
    Code: 48 c1 ea 03 80 3c 02 00 0f 85 6e 20 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 6e 10 49 8d bd d0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 59 20 00 00 4d 8b a5 d0 00 00 00 31 ff 41 81 e4
    RSP: 0018:ffff8801c400f410 EFLAGS: 00010202
    RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8618d325
    RDX: 000000000000001a RSI: ffffffff86189f97 RDI: 00000000000000d0
    RBP: ffff8801c400f608 R08: ffff8801c8fb4300 R09: 0000000000000000
    R10: ffffed0038801ed7 R11: 0000000000000003 R12: ffff8801d327d358
    R13: 0000000000000000 R14: ffff8801c16dd8c0 R15: 0000000000000004
    FS:  00007fe003615700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007fe1f3c43db8 CR3: 00000001bebb2000 CR4: 00000000001406f0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     napi_gro_frags+0x3f4/0xc90 net/core/dev.c:5715
     tun_get_user+0x31d5/0x42a0 drivers/net/tun.c:1922
     tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1967
     call_write_iter include/linux/fs.h:1808 [inline]
     new_sync_write fs/read_write.c:474 [inline]
     __vfs_write+0x6b8/0x9f0 fs/read_write.c:487
     vfs_write+0x1fc/0x560 fs/read_write.c:549
     ksys_write+0x101/0x260 fs/read_write.c:598
     __do_sys_write fs/read_write.c:610 [inline]
     __se_sys_write fs/read_write.c:607 [inline]
     __x64_sys_write+0x73/0xb0 fs/read_write.c:607
     do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x457579
    Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
    RSP: 002b:00007fe003614c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
    RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579
    RDX: 0000000000000012 RSI: 0000000020000000 RDI: 000000000000000a
    RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe0036156d4
    R13: 00000000004c5574 R14: 00000000004d8e98 R15: 00000000ffffffff
    Modules linked in:
    
    RIP: 0010:dev_gro_receive+0x132/0x2720 net/core/dev.c:5427
    Code: 48 c1 ea 03 80 3c 02 00 0f 85 6e 20 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 6e 10 49 8d bd d0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 59 20 00 00 4d 8b a5 d0 00 00 00 31 ff 41 81 e4
    RSP: 0018:ffff8801c400f410 EFLAGS: 00010202
    RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8618d325
    RDX: 000000000000001a RSI: ffffffff86189f97 RDI: 00000000000000d0
    RBP: ffff8801c400f608 R08: ffff8801c8fb4300 R09: 0000000000000000
    R10: ffffed0038801ed7 R11: 0000000000000003 R12: ffff8801d327d358
    R13: 0000000000000000 R14: ffff8801c16dd8c0 R15: 0000000000000004
    FS:  00007fe003615700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007fe1f3c43db8 CR3: 00000001bebb2000 CR4: 00000000001406f0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    
    Fixes: 90e33d45 ("tun: enable napi_gro_frags() for TUN/TAP driver")
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    af3fb24e
tun.c 81.3 KB