Re: Question: short-read while loading .so file

[Szabolcs Nagy <szabolcs dot nagy at arm dot com>]

On 05/06/15 16:51, ISHIKAWA,chiaki wrote:
> My surprise was that during the test of mozilla thunderbird when I
> I injected the "short read" to a few  files, I made a mistake of
> applying short tread to a few .so files and
> I observed that these *.so files were dynamically loaded by such short
> |read|.

dynamic linker is a libc issue so send the report
to libc-alpha instead of binutils mailing list.
(assuming you use glibc).

> That is, when the request to read these relatively small .so files by
> |read| with requested # of octets being 4096, my hand-crafted prelaoded
> |read| reads only 4036 (4096 - 60) octets, but
> the dynamic loader did not request the remaining 60 octets, and merrily
> went on running.
> 
> My question is:
> 
> Does the loader handle "short read" properly by issuing additional
> |read| if it notices that it needs to read more octets which are missing
> from the data structure  read partially by the first |read|?
> 
> Or was I just lucky that the last 60 octets (and presumably more octets
> before the last 60 octets) were mere fillers and the real code and data
> lived only the initial portion of 4096 octets, and that the failure to
> read the last 60 octets did not cause any issues in this particular run?
> 

sounds like a bug, but libc-alpha will know better

> Yes, the mozilla thunderbird did not crash or anything although no
> additional read was issued to read the remaining 60 octets.
> 
> That is why I am asking this question.
> 
> Thank you in advance for your attention.
> 
> Best Regards,
> Chiaki Ishikawa
> 
> 
> 
> 
> 
>