gcry_sexp_find_token() error checking

Werner Koch wk at gnupg.org
Fri Jun 10 12:00:04 CEST 2005

On Tue, 7 Jun 2005 15:52:09 -0700 , Bopp, Eric said:

> gcry_sexp_find_token() can result in a segmentation fault.  We are looking
> at ways to prevent sending bad data to the function but we also want to
> investigate ways to improve error checking in the function.  The problem we

The really question here is how did it happen that you came up with
inconsistent data.  LIST is an internalmobject of libgcrypt and thus
the actual must be somewhere in Libgcrypt at a place where LIST has
been created or modified.

> and used to increment "p".  The next dereference of "p" may cause a seg

    while ( *p != ST_STOP ) {
	if ( *p == ST_OPEN && p[1] == ST_DATA ) {

Failing at p[1] we can conclude that the CLOSE token is missing.

> Could someone more knowledgeable about the library tell me whether doing
> this will break the function?

You would hide the real problem with such a workaround.



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