Bug#452789: xxd segfaults with large values for -c

Bram Moolenaar Bram at moolenaar.net
Thu Nov 29 20:19:10 UTC 2007


James -

> On Wed, Nov 28, 2007 at 09:19:46AM -0500, James Vega wrote:
> > On Tue, Nov 27, 2007 at 10:26:31PM +0100, Bram Moolenaar wrote:
> > > I'm not the maintainer of xxd, but since it's included with Vim I tried
> > > fixing it anyway.  Please try the patch below and check that it fixes
> > > the problem for you.
> > 
> > That does work. Thanks.
> 
> Actually, I was incorrect.  I still see crashes when using values larger
> than 140 for -c.  The following was from running
> "xxd -b -c 145 /usr/bin/xxd".

Hmm, I still underestimated the size of the array needed for the bitwise
display.  Try this new diff:

*** ../vim-7.1.163/src/xxd/xxd.c	Thu May 10 19:07:42 2007
--- src/xxd/xxd.c	Thu Nov 29 21:05:16 2007
***************
*** 212,218 ****
  
  #define TRY_SEEK	/* attempt to use lseek, or skip forward by reading */
  #define COLS 256	/* change here, if you ever need more columns */
! #define LLEN (9 + (5*COLS-1)/2 + 2 + COLS)
  
  char hexxa[] = "0123456789abcdef0123456789ABCDEF", *hexx = hexxa;
  
--- 212,218 ----
  
  #define TRY_SEEK	/* attempt to use lseek, or skip forward by reading */
  #define COLS 256	/* change here, if you ever need more columns */
! #define LLEN (11 + (9*COLS-1)/1 + COLS + 2)
  
  char hexxa[] = "0123456789abcdef0123456789ABCDEF", *hexx = hexxa;
  
***************
*** 590,596 ****
        default:			octspergrp = 0; break;
        }
  
!   if (cols < 1 || (!hextype && (cols > COLS)))
      {
        fprintf(stderr, "%s: invalid number of columns (max. %d).\n", pname, COLS);
        exit(1);
--- 590,597 ----
        default:			octspergrp = 0; break;
        }
  
!   if (cols < 1 || ((hextype == HEX_NORMAL || hextype == HEX_BITS)
! 							    && (cols > COLS)))
      {
        fprintf(stderr, "%s: invalid number of columns (max. %d).\n", pname, COLS);
        exit(1);
***************
*** 750,755 ****
--- 751,757 ----
  	}
        if (ebcdic)
  	e = (e < 64) ? '.' : etoa64[e-64];
+       /* When changing this update definition of LLEN above. */
        l[11 + (grplen * cols - 1)/octspergrp + p] =
  #ifdef __MVS__
  	  (e >= 64)


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 /// Bram Moolenaar -- Bram at Moolenaar.net -- http://www.Moolenaar.net   \\\
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\\\        download, build and distribute -- http://www.A-A-P.org        ///
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