CVS commit: src/libexec/ld.elf_so

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Jul 19 19:56:06 UTC 2026

Modified Files:
        src/libexec/ld.elf_so: rtld.c

Log Message:
ld.elf_so: Set _rtld_objself.refcount = 1.

This is the object for ld.elf_so itself.  It can be opened with
dlopen("/usr/libexec/ld.elf_so"), and paths downstream of that assert
that the returned object has refcount > 0 to detect use-after-free
mistakes in rtld.  Since ld.elf_so must never be unloaded, let's just
make sure the reference count is always positive.

(It's conceivable that one could dlopen an object with a DT_RPATH
entry having "/usr/libexec" and a DT_NEEDED entry having "ld.elf_so",
causing recursive loading of ld.elf_so -- and if one then dlcloses
the same object, it might lead to trying to free _rtld_objself.  So
perhaps _rtld_load_object should just increment the reference count
of _rtld_objself itself.  But this is a simpler change that already
fixes some existing tests -- such as any rump tests -- when used with
an ld.elf_built with -DDEBUG.)

Followup for:

PR lib/59751: dlclose is not MT-safe depending on the libraries
unloaded


To generate a diff of this commit:
cvs rdiff -u -r1.227 -r1.228 src/libexec/ld.elf_so/rtld.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.