Re: [Bug-apl] Possible bug in APL

[Juergen Sauermann]

Hi Chris,

even after a close look at the GNU APL code I can't see anything wrong with how realpath() is being called.

To me it looks more like a bug in glibc 2.3, although the valgrind message suggests that this bug causes no harm
(a memory area is copied to itself, which is an overlap but one that causes no harm).

It also looks to me as if you are using an older GNU APL version because I cannot
find the line in Libpath.cc that you quote below in the current GNU APL code.

Thank you nevertheless for reporting this.

/// Jürgen

On 06/24/2018 02:29 PM, Chris Moller wrote:

Doing some other stuff involving libapl.so, I was running valgrind against my own code when this popped up:

==14122== Source and destination overlap in mempcpy(0x778a9e1, 0x778a9e1, 4)
==14122==    at 0x4C34FF0: mempcpy (vg_replace_strmem.c:1524)
==14122==    by 0x7E06634: realpath@@GLIBC_2.3 (in /usr/lib64/libc-2.27.so)
==14122==    by 0x7441092: LibPaths::search_APL_lib_root() (LibPaths.cc:186)
==14122==    by 0x7441173: LibPaths::init(char const*, bool) (LibPaths.cc:53)
==14122==    by 0x7422B96: init_1(char const*, bool) (Common.cc:77)
==14122==    by 0x7509C09: init_libapl (libapl.cc:435)
==14122==    by 0x4048F9: main (gapl.c:685)

The line in LibPaths.cc is:

unused = realpath(APL_lib_root, APL_lib_root);

which could obviously cause a collision. 

I don't know if this is a real problem or not, but I thought I ought to  mention it to someone.

Chris Moller

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