In case of an explicit loader invocation, ld.so essentially performs
a dlopen call to load the main executable. Since the pathname of
the executable is known at this point, it gets stored in the link
map. In regular mode, the pathname is not known and "" is used
instead.
As a result, if a program calls dlopen on the pathname of the main
program, the dlopen call succeeds and returns a handle for the main
map. This results in an unnecessary difference between glibc
testing (without --enable-hardcoded-path-in-tests) and production
usage.
This commit discards the names when building the link map in
_dl_new_object for the main executable, but it still determines
the origin at this point in case of an explict loader invocation.
The reason is that the specified pathname has to be used; the kernel
has a different notion of the main executable.
dlopen can no longer open PIE binaries, so it is not necessary
to link the executable as non-PIE to trigger a dlopen failure.
If we hard-code the path to the real executable, we can run the test
with and without hard-coded paths because the dlopen path will not
be recognized as the main program in both cases. (With an explict
loader invocation, the loader currently adds argv[0] to l_libname
for the main map and the dlopen call suceeds as a result; it does
not do that in standard mode.)
The elf/tst-dlopen-aout.c test uses asserts to verify properties of the
test execution. Instead of using assert it should use xpthread_create
and xpthread_join to catch errors starting the threads and fail the
test. This shows up in Fedora 28 when building for i686-pc-linux-gnu
and using gcc 8.1.1.
Tested on i686, and fixes a check failure with -DNDEBUG.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
An application that erroneously tries to repeatedly dlopen("a.out", ...)
may hit assertion failure:
Inconsistency detected by ld.so: dl-tls.c: 474: _dl_allocate_tls_init:
Assertion `listp != ((void *)0)' failed!
dlopen() actually fails with "./a.out: cannot dynamically load executable",
but it does so after incrementing dl_tls_max_dtv_idx.
Once we run out of TLS_SLOTINFO_SURPLUS (62), we exit with above assertion
failure.
2014-03-24 Paul Pluzhnikov <ppluzhnikov@google.com>
[BZ #16634]
* elf/dl-load.c (open_verify): Add mode parameter.
Error early when ET_EXEC and mode does not have __RTLD_OPENEXEC.
(open_path): Change from boolean 'secure' to complete flag 'mode'
(_dl_map_object): Adjust.
* elf/Makefile (tests): Add tst-dlopen-aout.
* elf/tst-dlopen-aout.c: New test.
