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Date: Mon, 25 Jan 2010 17:10:32 +0000
Message-ID: <6278d2221001250910i41f43a27y4db92f9ef17439cc@mail.gmail.com>
Subject: [2.6.32.3] potentially uninitialised field in nfs_atomic_lookup...
From: Daniel J Blueman <daniel.blueman@gmail.com>
To: linux-nfs@vger.kernel.org, Trond Myklebust <trond.myklebust@fys.uio.no>
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When booting with 2.6.32.3 x86-64 with a debug configuration including
kmemcheck activated, I'm seeing bytes reported as uninitialised [1]
(here with value 0x33).

This is with automount and NFS4 [2] and reproduces consistently; it
appears to not be structure padding.

What additional information would help on this?

Daniel

--- [1]

WARNING: kmemcheck: Caught 64-bit read from uninitialized memory
(ffff88016cc180c8)

07000000000000003333333333333333808d7e6d0188ffff988d7e6d0188ffff

 i i i i i i i i u u u u u u u u i i i i i i i i i i i i i i i i



Modules linked in: nfs lockd nfs_acl auth_rpcgss netconsole configfs
autofs4 sunrpc af_packet ipv6 msr binfmt_misc dm_mod nvram evdev
psmouse rtc_cmos rtc_core rtc_lib e1000e piix pata_acpi
ide_pci_generic ata_generic rng_core ext3 jbd mbcache uhci_hcd
ohci_hcd ehci_hcd usbcore [last unloaded: microcode]

 [<ffffffffa0236d2e>] nfs_atomic_lookup+0xce/0x110 [nfs]

 [<ffffffff8113e13a>] do_lookup+0x1da/0x220

 [<ffffffff8113e5c0>] __link_path_walk+0x440/0x760

 [<ffffffff8113e937>] path_walk+0x57/0xb0

 [<ffffffff8113e9fa>] vfs_path_lookup+0x6a/0xe0

 [<ffffffffa023f370>] nfs_follow_remote_path+0x50/0x150 [nfs]

 [<ffffffffa023fe97>] nfs4_try_mount+0x77/0xd0 [nfs]

 [<ffffffffa024107b>] nfs4_get_sb+0x13b/0x320 [nfs]

 [<ffffffff81134e18>] vfs_kern_mount+0x58/0xe0

 [<ffffffff81134f0e>] do_kern_mount+0x4e/0x110

 [<ffffffff8114dd06>] do_mount+0x546/0x7c0

 [<ffffffff8114e00a>] sys_mount+0x8a/0xd0

 [<ffffffff8100be2b>] system_call_fastpath+0x16/0x1b

 [<ffffffffffffffff>] 0xffffffffffffffff


--- [2]

auto.direct /net/home autofs
rw,relatime,fd=5,pgrp=4013,timeout=300,minproto=5,maxproto=5,direct 0
0
filer:/home /net/home nfs4
rw,relatime,vers=4,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=65535,timeo=600,retrans=3,sec=sys,clientaddr=172.16.0.130,addr=172.16.0.110
0 0

--- [3]

/net/cluster/daniel/kernel/linux-2.6.32.3/fs/nfs/dir.c:1044
    3cf1:       48 8b 5d e8             mov    -0x18(%rbp),%rbx
    3cf5:       4c 8b 65 f0             mov    -0x10(%rbp),%r12
    3cf9:       48 89 c8                mov    %rcx,%rax
    3cfc:       4c 8b 6d f8             mov    -0x8(%rbp),%r13
    3d00:       c9                      leaveq
    3d01:       c3                      retq
/net/cluster/daniel/kernel/linux-2.6.32.3/fs/nfs/dir.c:1022
    3d02:       83 f8 ec                cmp    $0xffffffffffffffec,%eax
    3d05:       74 19                   je     3d20 <nfs_atomic_lookup+0xc0>
    3d07:       83 f8 fe                cmp    $0xfffffffffffffffe,%eax
    3d0a:       74 5e                   je     3d6a <nfs_atomic_lookup+0x10a>
    3d0c:       83 f8 d8                cmp    $0xffffffffffffffd8,%eax
    3d0f:       90                      nop
    3d10:       75 df                   jne    3cf1 <nfs_atomic_lookup+0x91>
/net/cluster/daniel/kernel/linux-2.6.32.3/fs/nfs/dir.c:1031
    3d12:       f6 83 8a 00 00 00 02    testb  $0x2,0x8a(%rbx)
    3d19:       75 d6                   jne    3cf1 <nfs_atomic_lookup+0x91>
    3d1b:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)
/net/cluster/daniel/kernel/linux-2.6.32.3/fs/nfs/dir.c:1043
    3d20:       48 89 da                mov    %rbx,%rdx
    3d23:       4c 89 e6                mov    %r12,%rsi
    3d26:       4c 89 ef                mov    %r13,%rdi
    3d29:       e8 22 fd ff ff          callq  3a50 <nfs_lookup>
    3d2e:       48 89 c1                mov    %rax,%rcx <----
    3d31:       eb be                   jmp    3cf1 <nfs_atomic_lookup+0x91>
/net/cluster/daniel/kernel/linux-2.6.32.3/fs/nfs/dir.c:1014
    3d33:       31 f6                   xor    %esi,%esi
    3d35:       4c 89 e7                mov    %r12,%rdi
    3d38:       e8 00 00 00 00          callq  3d3d <nfs_atomic_lookup+0xdd>
    3d3d:       31 c9                   xor    %ecx,%ecx
    3d3f:       eb b0                   jmp    3cf1 <nfs_atomic_lookup+0x91>

static struct dentry *nfs_atomic_lookup(struct inode *dir, struct dentry *dentr
{
...
         } else if (res != NULL)
                dentry = res;
out:
        return res;
no_open:
        return nfs_lookup(dir, dentry, nd);  <---
}
-- 
Daniel J Blueman