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php4-beta | 199912

Re: [PHP4BETA] ABR: Array bounds read in ZTS mode + explanation. From: Thies C. Arntzen (thies <email protected>)
Date: 12/27/99

On Mon, 27 Dec 1999, Zeev Suraski wrote:

> On Mon, 27 Dec 1999, Thies C. Arntzen wrote:
>
> > **** Purify instrumented bin/nsd (pid 22145) ****
> > ABR: Array bounds read (9440 times):
> > * This is occurring while in thread 10:
> > memcpy [rtlib.o]
> > zend_hash_copy [zend_hash.c:861]
> > compiler_globals_ctor [zend.c:247]
> > allocate_new_resource [TSRM.c:200]
> > ts_resource [TSRM.c:235]
> > php_ns_request_handler [aolserver.c:500]
> > * Reading 60 bytes from 0x264ec8 in the heap (44 bytes at 0x264ed8 illegal).
> > * Address 0x264ec8 is at the beginning of a malloc'd block of 16 bytes.
> > * This block was allocated from:
> > malloc [rtlib.o]
> > zend_hash_add_or_update [zend_hash.c:189]
> > zend_register_functions [zend_API.c:698]
> > zend_startup_builtin_functions [zend_builtin_functions.c:78]
> > zend_startup [zend.c:363]
> >
> > problem is :
> >
> > zend_API.c line 698
> > if (zend_hash_add(target_function_table, ptr->fname, strlen(ptr->fname)+1, &internal_function, sizeof(zend_internal_function), NULL) == FAILURE) {
> > unload=1;
> > break;
> > }
> >
> > zend.c line 238:
> > zend_hash_copy(compiler_globals->function_table, global_function_table, NULL, &tmp_func, sizeof(zend_function));
> >
> >
> > but: sizeof(zend_function) > sizeof(zend_internal_function) so we're
> > coying uninted memory (as purify tells us) in compiler_globals_ctor().
>
> Well, that's one of the places that purify reports, correctly from its
> point of view, but that we really don't care about.

reading beyond a malloced block is not considered safe AFAIK. it is very,
very unlikely but it could cause trouble. i can easily live with it, but
i think it's bad style. how bad would be the penalty if we tried for a
clean solution?

tc

>
> Zeev
>
> --
> Zeev Suraski <zeev <email protected>>
> http://www.zend.com/
>
>

Thies C. Arntzen "One Big-Mac, Small Fries and a Coke!"
Digital Collections Phone +49 40 235350 Fax +49 40 23535180
Hammerbrookstr. 93 20097 Hamburg / Germany 

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