[Bug dyninst/22004] dyninst gets a SIGSEGV with glibc 2.25.90

["scox at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=22004

--- Comment #1 from Stan Cox <scox at redhat dot com> ---
The problem seems related to the expanded use of ifunc in libc 2.25.90. This
could occur with any use of ifunc most probably, it just so happens recent libc
has expanded use of it so we will probably see expanded use of it:
ifunc description

Going through the last few stack frame entries where things go awry:

frame 5 0x00007fca65776c99 in Dyninst::ParseAPI::CFGFactory::_mkfunc
(this=this@entry=0x9aa2c0, addr=addr@entry=132480,
src=src@entry=Dyninst::ParseAPI::RT, name="targ20580", obj=obj
@Entry=0x1076590, reg=reg@entry=0x1d058f0, isrc=0x21744c0)
at
/root/brew-rpms/dyninst-9.3.2-1/BUILD/dyninst-9.3.2/dyninst-9.3.2/parseAPI/src/CFGFactory.C:91
91 Function * ret = mkfunc(addr,src,name,obj,reg,isrc);

where addr = 0x20580 is
Disassembly of section .plt:
0000000000020580 <ABS+0x98e00 at plt>:
20580: ff 25 fa 0a 3c 00 jmpq *0x3c0afa(%rip) # 3e1080
<GLOBAL_OFFSET_TABLE+0x80>
20586: 68 19 00 00 00 pushq $0x19
2058b: e9 10 ff ff ff jmpq 204a0 <catch_hook+0x20418>

where 3e1080 is
Relocation section '.rela.plt' at offset 0x200f0 contains 39 entries:
Offset Info Type Sym. Value Sym. Name + Addend
...
0000003e1080 000000000025 R_X86_64_IRELATIV 98e00

where 98e00 is
Symbol table '.dynsym' contains 2294 entries:
793: 0000000000098e00 42 IFUNC GLOBAL DEFAULT 13 strlen @@ GLIBC_2.2.5

frame 4 0x00007fca65d98813 in DynCFGFactory::mkfunc (this=this @
entry=0x9aa2c0, addr=addr@entry=132480,
src=src@entry=Dyninst::ParseAPI::RT, name="", obj=obj @ entry=0x1076590,
reg=reg@entry=0x1d058f0, isrc=)
at
/root/brew-rpms/dyninst-9.3.2-1/BUILD/dyninst-9.3.2/dyninst-9.3.2/dyninstAPI/src/Parsing.C:164
164 ret = new parse_func(stf, pdmod,_img,obj,reg,isrc,src);

where stf is stf = new PLTFunction(*i);
(if I understand things correctly a function object is being created for the
plt entry)
where *i is the relocation for this plt entry. For ifunc this is the
R_*IRELATIV relocation.
this results in stf.firstSymbol = NULL

frame 3 0x00007fca65d7b5c0 in parse_func::parse_func (this=0x2613a10,
func=0x2611c60, m=0x8c5770, i=0x816e50, obj=0x1076590,
reg=0x1d058f0, isrc=0x21744c0, src=Dyninst::ParseAPI::RT)
at
/root/brew-rpms/dyninst-9.3.2-1/BUILD/dyninst-9.3.2/dyninst-9.3.2/dyninstAPI/src/parse-cfg.C:91
91
Function(func->getOffset(),func->getFirstSymbol()->getMangledName(),obj,reg,isrc),

where func->getFirstSymbol() is NULL so we get a SIGSEGV

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