Comment 9 for bug 1842730

Created attachment 10522
a fairly simple reproducer

As a case in point here is a reproducer that I whipped up based upon a customer report.

[ben@Mustang dl-bug]$ make all
cc -g -c -o main.o main.c
cc -g -o main main.o -ldl
cc -g -c -fpic a.c
cc -g -c -fpic d.c
cc -g -fpic -shared -Wl,-z,nodelete -o libd.so d.o
cc -g -c -fpic e.c
cc -g -fpic -shared -o libe.so e.o
cc -g -fpic -shared -o liba.so a.o -L. -ld -le
cc -g -c -fpic b.c
cc -g -fpic -shared -o libb.so b.o -L. -ld
[ben@Mustang dl-bug]$ make run
LD_LIBRARY_PATH=. ./main
d_fn x=12
inside b_fn
rm libe.so
LD_LIBRARY_PATH=. ./main
Could not open liba.so - libe.so: cannot open shared object file: No such file or directory
make: *** [Makefile:38: run] Segmentation fault (core dumped)

Note that libd.so is marked NODELETE
So when main dlopen's liba.so which needs on libd.so and libe.so because libe.so is missing, the load of liba.so fails. This is expected. However, when libb.so is loaded which also needs libd.so the application crashes because the relocations haven't been done.

[ben@Mustang dl-bug]$ LD_LIBRARY_PATH=. LD_DEBUG=reloc,files ./main 2> foo
d_fn x=12
inside b_fn
[ben@Mustang dl-bug]$ egrep file\|reloc foo
     10901: file=libdl.so.2 [0]; needed by ./main [0]
     10901: file=libdl.so.2 [0]; generating link map
     10901: file=libc.so.6 [0]; needed by ./main [0]
     10901: file=libc.so.6 [0]; generating link map
     10901: relocation processing: /lib64/libc.so.6
     10901: relocation processing: /lib64/libdl.so.2
     10901: relocation processing: ./main (lazy)
     10901: relocation processing: /lib64/ld-linux-x86-64.so.2
     10901: file=liba.so [0]; dynamically loaded by ./main [0]
     10901: file=liba.so [0]; generating link map
     10901: file=libd.so [0]; needed by ./liba.so [0]
     10901: file=libd.so [0]; generating link map
     10901: file=libe.so [0]; needed by ./liba.so [0]
     10901: file=libe.so [0]; generating link map
     10901: relocation processing: ./libe.so
     10901: relocation processing: ./libd.so
     10901: relocation processing: ./liba.so
     10901: opening file=./liba.so [0]; direct_opencount=1
     10901: file=libb.so [0]; dynamically loaded by ./main [0]
     10901: file=libb.so [0]; generating link map
     10901: relocation processing: ./libb.so
     10901: opening file=./libb.so [0]; direct_opencount=1

vs.

[ben@Mustang dl-bug]$ rm libe.so
[ben@Mustang dl-bug]$ LD_LIBRARY_PATH=. LD_DEBUG=reloc,files ./main 2> foo
Segmentation fault (core dumped)
[ben@Mustang dl-bug]$ egrep file\|reloc foo
     10965: file=libdl.so.2 [0]; needed by ./main [0]
     10965: file=libdl.so.2 [0]; generating link map
     10965: file=libc.so.6 [0]; needed by ./main [0]
     10965: file=libc.so.6 [0]; generating link map
     10965: relocation processing: /lib64/libc.so.6
     10965: relocation processing: /lib64/libdl.so.2
     10965: relocation processing: ./main (lazy)
     10965: relocation processing: /lib64/ld-linux-x86-64.so.2
     10965: file=liba.so [0]; dynamically loaded by ./main [0]
     10965: file=liba.so [0]; generating link map
     10965: file=libd.so [0]; needed by ./liba.so [0]
     10965: file=libd.so [0]; generating link map
     10965: file=libe.so [0]; needed by ./liba.so [0]
     10965: file=./liba.so [0]; destroying link map
Could not open liba.so - libe.so: cannot open shared object file: No such file or directory
     10965: file=libb.so [0]; dynamically loaded by ./main [0]
     10965: file=libb.so [0]; generating link map
     10965: relocation processing: ./libb.so

Note on the failing case the relocations are never done on libd.so