dlfcn: Failures after dlmopen should not terminate process [BZ #24772]

Commit 9e78f6f6e7134a5f299cc8de77370218f8019237 ("Implement
_dl_catch_error, _dl_signal_error in libc.so [BZ #16628]") has the
side effect that distinct namespaces, as created by dlmopen, now have
separate implementations of the rtld exception mechanism.  This means
that the call to _dl_catch_error from libdl in a secondary namespace
does not actually install an exception handler because the
thread-local variable catch_hook in the libc.so copy in the secondary
namespace is distinct from that of the base namepace.  As a result, a
dlsym/dlopen/... failure in a secondary namespace terminates the process
with a dynamic linker error because it looks to the exception handler
mechanism as if no handler has been installed.

This commit restores GLRO (dl_catch_error) and uses it to set the
handler in the base namespace.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/elf/dl-error-skeleton.c b/elf/dl-error-skeleton.c
index 2fd62777cf..b699936c6e 100644
--- a/elf/dl-error-skeleton.c
+++ b/elf/dl-error-skeleton.c
@@ -248,4 +248,16 @@ _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)
   catch_hook = old_catch;
   receiver = old_receiver;
 }
+
+/* Forwarder used for initializing GLRO (_dl_catch_error).  */
+int
+_rtld_catch_error (const char **objname, const char **errstring,
+		   bool *mallocedp, void (*operate) (void *),
+		   void *args)
+{
+  /* The reference to _dl_catch_error will eventually be relocated to
+     point to the implementation in libc.so.  */
+  return _dl_catch_error (objname, errstring, mallocedp, operate, args);
+}
+
 #endif /* DL_ERROR_BOOTSTRAP */