Re: [OOPS] 3.0-rc1 cifs

From: Martijn Uffing
Date: Thu Jun 09 2011 - 20:57:42 EST



<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>

Martijn


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