linux-kernel - Re: [OOPS] 3.0-rc1 cifs

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Date:	Sat, 11 Jun 2011 00:03:31 +0200 (CEST)
From:	Martijn Uffing <mp3project@...ijopen.student.utwente.nl>
To:	Jeff Layton <jlayton@...hat.com>
cc:	Connor Hansen <cmdkhh@...il.com>, linux-cifs@...r.kernel.org,
	linux-kernel@...r.kernel.org, sean finney <seanius@...nius.net>
Subject: Re: [OOPS] 3.0-rc1 cifs


On Fri, 10 Jun 2011, Jeff Layton wrote:

> On Fri, 10 Jun 2011 02:57:21 +0200 (CEST)
> Uffing <mp3project@...ijopen.student.utwente.nl> wrote:
>
>>
>> <snip>
>>> call in get_dfs_path()
>>> rc = CIFSTCon(xid, pSesInfo, temp_unc, NULL, nls_codepage);
>>>
>>> function header for CIFSTCon
>>> int  CIFSTCon(unsigned int xid, struct cifs_ses *ses,
>>>          const char *tree, struct cifs_tcon *tcon,
>>>          const struct nls_table *nls_codepage)
>>>
>>> get_dfs_path() is passing struct cifs_tcon *tcon as NULL
>>>
>>> from config:  CONFIG_CIFS_WEAK_PW_HASH=y
>>>
>>> in CIFSTCon
>>>
>>> #ifdef CONFIG_CIFS_WEAK_PW_HASH
>>> 3222                 if ((global_secflags & CIFSSEC_MAY_LANMAN) &&
>>> 3223                     (ses->server->secType == LANMAN))
>>> 3224                         calc_lanman_hash(tcon->password,
>>> ses->server->cryptkey,
>>>
>>> in calc_lanman_hash tcon is dereferenced(tcon->password) without being
>>> checked if null
>>>
>>> 3225                                          ses->server->sec_mode &
>>> 3226                                             SECMODE_PW_ENCRYPT ?
>>> true : false,
>>> 3227                                          bcc_ptr);
>>> 3228                 else
>>> 3229 #endif /* CIFS_WEAK_PW_HASH */
>>>
>>> Connor
>>
>>
>> Ave all
>>
>> I recompiled  kernel 3.0-rc1 (hadn't enabled CONFIG_DEBUG_INFO=y) and put
>> the oops (with the new adresses) through gdb per instruction of Jeff. And
>> Connor was spot on!
>>
>> <qoute oops>
>> BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0
>> IP: [<ffffffffa041e286>] CIFSTCon+0xf6/0x4d0 [cifs]
>> </qoute oops>
>>
>> <qoute gdb>
>> This GDB was configured as "x86_64-linux-gnu".
>> For bug reporting instructions, please see:
>> <http://www.gnu.org/software/gdb/bugs/>...
>> Reading symbols from
>> /lib/modules/3.0.0-rc1-debug/kernel/fs/cifs/cifs.ko...done.
>> (gdb) list *(CIFSTCon+0xf6)
>> 0xc2b6 is in CIFSTCon (fs/cifs/connect.c:3230).
>> 3225                                             ses->server->sec_mode &
>> 3226                                                SECMODE_PW_ENCRYPT ?
>> true : false,
>> 3227                                             bcc_ptr);
>> 3228                    else
>> 3229    #endif /* CIFS_WEAK_PW_HASH */
>> 3230                    rc = SMBNTencrypt(tcon->password,
>> ses->server->cryptkey,
>> 3231                                            bcc_ptr);
>> 3232
>> 3233                    bcc_ptr += CIFS_AUTH_RESP_SIZE;
>> 3234                    if (ses->capabilities & CAP_UNICODE) {
>> (gdb)
>> </qoute gdb>
>>
>
> (cc'ing Sean F. since I suspect this regression is due to his changes)
>
> Thanks for the analysis, Martijn and Connor...
>
> What sort of server are you mounting here? It looks like it's using
> share-level security, so it's either very old or is a samba server
> configured that way.

To be honest ... both :)
a)server is Debian Etch (samba 3.0.24-6etch10)
   (yeah i know old, but no time at the moment to upgrade/reinstall the
   whole system)
b)share security. (security=share) in smb.conf
   This is on purpose. (all access is shielded based on hostnames)

Mu

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