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From: "hjl.tools at gmail dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug dynamic-link/20019] NULL pointer dereference in libc.so.6 IFUNC
 due to uninitialized GOT
Date: Thu, 11 Mar 2021 12:58:56 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D20019

--- Comment #29 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to yangyanchao6@huawei.com from comment #28)

> [root@localhost DTS2021030805K7VLP1D00]# gcc -O2   -c -o main.o main.c
> [root@localhost DTS2021030805K7VLP1D00]# gcc -O2 -fPIC   -c -o foo.o foo.c
> [root@localhost DTS2021030805K7VLP1D00]# gcc -O2 -fPIC   -c -o bar.o bar.c
> [root@localhost DTS2021030805K7VLP1D00]# ld.gold -shared  -z now -o
> libbar.so bar.o
> [root@localhost DTS2021030805K7VLP1D00]# ld.gold -shared  -z now -o
> libfoo.so foo.o libbar.so

Never use ld directly unless you know what you are getting.

> [root@localhost DTS2021030805K7VLP1D00]# gcc -o foo main.o libfoo.so
> -Wl,-rpath,.=20
> [root@localhost DTS2021030805K7VLP1D00]# ./foo=20
> ./foo: Relink `./libbar.so' with `/usr/lib64/libc.so.6' for IFUNC symbol
> `memmove'
> Segmentation fault (core dumped)
> [root@localhost DTS2021030805K7VLP1D00]# readelf -r libbar.so
>=20
>

--=20
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