[PATCH] avoid lock oder violation between xattr.tdb and g_lock.tdb

Steve French smfrench at gmail.com
Wed Jul 20 17:03:07 UTC 2016

On Wed, Jul 20, 2016 at 12:51 AM, Volker Lendecke <vl at samba.org> wrote:
> On Tue, Jul 19, 2016 at 08:47:47PM -0500, Steve French wrote:
>> Running this series of Volker's patches on 4.4-test (adding the one earlier
>> patch needed for the missing #define SERVER_ID_BUF_LENGTH
>> ) we got a different oops (in get_share_mode_write_time due to corrupt lock
>> contents).
>> Are there other coreq patches that would need to backport this to 4.4-test
>> (or is it safer to use Michael's original small patch ... or ...)?
> Can you reproduce this somehow and get me more info like a stack trace
> or the corrupted contents? And, your exact patchset? I will need to
> backport this to 4.4 and 4.3 for a customer too, so any information
> will be very interesting for me.
> Thanks,
> Volker

Created large directory tree and did ls -lR (from cifs mount to Samba
4.4-test branch equivalent to about two weeks ago + your patch
series).   (By the way Michael's small original patch did work without
problems in the same scenario as an alternative).

#0  0x00007fc99911b5f7 in raise () from /lib64/libc.so.6
#1  0x00007fc99911cce8 in abort () from /lib64/libc.so.6
#2  0x00007fc99a65dc6b in dump_core () from /lib64/libsmbconf.so.0
#3  0x00007fc99a6500f7 in smb_panic_s3 () from /lib64/libsmbconf.so.0
#4  0x00007fc99cf4eadf in smb_panic () from /lib64/libsamba-util.so.0
#5  0x00007fc99cf4ecf6 in sig_fault () from /lib64/libsamba-util.so.0
#6  <signal handler called>
#7  0x00007fc99cb921a4 in get_share_mode_write_time () from
#8  0x00007fc99cb92258 in get_file_infos () from
#9  0x00007fc99ca99ff8 in smbd_dirptr_get_entry () from
#10 0x00007fc99cad4c95 in smbd_dirptr_lanman2_entry () from
#11 0x00007fc99cb3731c in smbd_smb2_query_directory_send.isra.0 ()
from /usr/lib64/samba/libsmbd-base-samba4.so

#12 0x00007fc99cb37a44 in smbd_smb2_request_process_query_directory ()
from /usr/lib64/samba/libsmbd-base-samba4.so

#13 0x00007fc99cb2274d in smbd_smb2_request_dispatch () from

Lock contents are garbage

(gdb) f 8

#8  get_share_mode_write_time (lck=lck at entry=0x55b3ef2d2e80) at

1315            if (!null_timespec(d->changed_write_time)) {

(gdb) p *lck

$1 = {data = 0x2e}  ß-

(gdb) p lck

$2 = (struct share_mode_lock *) 0x55b3ef2d2e80

(gdb) p d

$3 = (struct share_mode_data *) 0x2e

(gdb) local

Undefined command: "local".  Try "help".

(gdb) print d

$4 = (struct share_mode_data *) 0x2e



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