Re: Unfortunately, not yet solved (Was: Re: Problem solved! (Was: Re: [xml] valgrind errrors with this small sample program))

[Daniel Veillard <veillard redhat com>]

On Wed, Mar 17, 2004 at 04:29:38PM +0100, Holger Rauch wrote:
> Hi Daniel!
>
> My problem *seems* to be solved for lixml2 2.6.7
> on Linux (valgrind doesn't report any errors),
> but not when using Purify (a commercial memory analysis tool) on
> Solaris. The Solaris I'm talking about is 2.8 running on a 64-bit system. I
> used gcc 2.95.3 to compile my sample program.
>
> It seems to me that valgrind does not detect such errors. So, probably it's
> also an error on Linux; it just doesn't show up in valgrind.
>
> > From Purify I get a UMR (Unitialized memory read) error with my small sample
> program (please see message
>
> http://mail.gnome.org/archives/xml/2004-March/msg00130.html
>
> for details. My small sample program is attached there.)
>
> The Purify log follows (unnecessary clutter ommitted;
> hope it is of some use to you). Could you (or to somebody else
> who is more familiar with libxml2 internals than I am) please take
> yet another look on this and maybe provide a patch that fixes this (probably
> minor) issue?

[...]
> UMR: Uninitialized memory read:
>   * This is occurring while in:
>       memcmp         [rtlib.o]
>       xmlParseEndTag2 [parser.c:7567]
>       xmlParseElement [parser.c:7941]
>       xmlParseContent [parser.c:7760]
>       xmlParseElement [parser.c:7920]
>       xmlParseContent [parser.c:7760]
>       xmlParseElement [parser.c:7920]
>       xmlParseDocument [parser.c:8511]
>       xmlSAXParseMemoryWithData [parser.c:11387]
>       xmlSAXParseMemory [parser.c:11419]
>       xmlParseMemory [parser.c:11433]
>       main           [xmlParseMemory-test-wrong-fragment.c:18]
>       _start         [crt1.o]
>   * Reading 15 bytes from 0xaabbe in the heap (3 bytes at 0xaabca uninit).
>   * Address 0xaabbe is 214 bytes into a malloc'd block at 0xaaae8 of 1024 bytes.
>   * This block was allocated from:
>       malloc         [rtlib.o]
>       xmlDictAddString [dict.c:103]
>       xmlDictLookup  [dict.c:573]
>       xmlDetectSAX2  [parser.c:605]
>       xmlSAXParseMemoryWithData [parser.c:11380]
>       xmlSAXParseMemory [parser.c:11419]
>       xmlParseMemory [parser.c:11433]
>       main           [xmlParseMemory-test-wrong-fragment.c:18]
>       _start         [crt1.o]

  Can you try to change line 7567 of parser.c from
    if ((tlen > 0) && (memcmp(ctxt->input->cur, ctxt->name, tlen) == 0)) {
to
    if ((tlen > 0) && (memcmp(ctxt->name, ctxt->input->cur, tlen) == 0)) {

 and see if this fixes Purify report ?

Daniel

-- 
Daniel Veillard      | Red Hat Network https://rhn.redhat.com/
veillard redhat com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/