• Filipe Manana's avatar
    Btrfs: send, fix incorrect ref access when using extrefs · 51a60253
    Filipe Manana authored
    When running send, if an inode only has extended reference items
    associated to it and no regular references, send.c:get_first_ref()
    was incorrectly assuming the reference it found was of type
    BTRFS_INODE_REF_KEY due to use of the wrong key variable.
    This caused weird behaviour when using the found item has a regular
    reference, such as weird path string, and occasionally (when lucky)
    a crash:
    
    [  190.600652] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
    [  190.600994] Modules linked in: btrfs xor raid6_pq binfmt_misc nfsd auth_rpcgss oid_registry nfs_acl nfs lockd fscache sunrpc psmouse serio_raw evbug pcspkr i2c_piix4 e1000 floppy
    [  190.602565] CPU: 2 PID: 14520 Comm: btrfs Not tainted 3.13.0-fdm-btrfs-next-26+ #1
    [  190.602728] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
    [  190.602868] task: ffff8800d447c920 ti: ffff8801fa79e000 task.ti: ffff8801fa79e000
    [  190.603030] RIP: 0010:[<ffffffff813266b4>]  [<ffffffff813266b4>] memcpy+0x54/0x110
    [  190.603262] RSP: 0018:ffff8801fa79f880  EFLAGS: 00010202
    [  190.603395] RAX: ffff8800d4326e3f RBX: 000000000000036a RCX: ffff880000000000
    [  190.603553] RDX: 000000000000032a RSI: ffe708844042936a RDI: ffff8800d43271a9
    [  190.603710] RBP: ffff8801fa79f8c8 R08: 00000000003a4ef0 R09: 0000000000000000
    [  190.603867] R10: 793a4ef09f000000 R11: 9f0000000053726f R12: ffff8800d43271a9
    [  190.604020] R13: 0000160000000000 R14: ffff8802110134f0 R15: 000000000000036a
    [  190.604020] FS:  00007fb423d09b80(0000) GS:ffff880216200000(0000) knlGS:0000000000000000
    [  190.604020] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
    [  190.604020] CR2: 00007fb4229d4b78 CR3: 00000001f5d76000 CR4: 00000000000006e0
    [  190.604020] Stack:
    [  190.604020]  ffffffffa01f4d49 ffff8801fa79f8f0 00000000000009f9 ffff8801fa79f8c8
    [  190.604020]  00000000000009f9 ffff880211013260 000000000000f971 ffff88021147dba8
    [  190.604020]  00000000000009f9 ffff8801fa79f918 ffffffffa02367f5 ffff8801fa79f928
    [  190.604020] Call Trace:
    [  190.604020]  [<ffffffffa01f4d49>] ? read_extent_buffer+0xb9/0x120 [btrfs]
    [  190.604020]  [<ffffffffa02367f5>] fs_path_add_from_extent_buffer+0x45/0x60 [btrfs]
    [  190.604020]  [<ffffffffa0238806>] get_first_ref+0x1f6/0x210 [btrfs]
    [  190.604020]  [<ffffffffa0238994>] __get_cur_name_and_parent+0x174/0x3a0 [btrfs]
    [  190.604020]  [<ffffffff8118df3d>] ? kmem_cache_alloc_trace+0x11d/0x1e0
    [  190.604020]  [<ffffffffa0236674>] ? fs_path_alloc+0x24/0x60 [btrfs]
    [  190.604020]  [<ffffffffa0238c91>] get_cur_path+0xd1/0x240 [btrfs]
    (...)
    
    Steps to reproduce (either crash or some weirdness like an odd path string):
    
        mkfs.btrfs -f -O extref /dev/sdd
        mount /dev/sdd /mnt
    
        mkdir /mnt/testdir
        touch /mnt/testdir/foobar
    
        for i in `seq 1 2550`; do
            ln /mnt/testdir/foobar /mnt/testdir/foobar_link_`printf "%04d" $i`
        done
    
        ln /mnt/testdir/foobar /mnt/testdir/final_foobar_name
    
        rm -f /mnt/testdir/foobar
        for i in `seq 1 2550`; do
            rm -f /mnt/testdir/foobar_link_`printf "%04d" $i`
        done
    
        btrfs subvolume snapshot -r /mnt /mnt/mysnap
        btrfs send /mnt/mysnap -f /tmp/mysnap.send
    Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
    Signed-off-by: default avatarChris Mason <clm@fb.com>
    Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
    51a60253
send.c 132 KB