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elf: Do not copy vDSO soname when setting up link map

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The kernel does not put the vDSO at special addresses, so writev can
write the name directly.  Also remove the incorrect comment about not
setting l_name.

Andy Lutomirski confirmed in
<https://lore.kernel.org/linux-api/442A16C0-AE5A-4A44-B261-FE6F817EAF3C@amacapital.net/>
that this copy is not necessary.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2021-02-12 18:22:59 +01:00
parent ce4a94b12e
commit ebcf45a16c
1 changed files with 5 additions and 12 deletions
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17
elf/setup-vdso.h
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@ -80,20 +80,13 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
l->l_local_scope[0]->r_list = &l->l_real;
/* Now that we have the info handy, use the DSO image's soname
so this object can be looked up by name. Note that we do not
set l_name here. That field gives the file name of the DSO,
and this DSO is not associated with any file. */
so this object can be looked up by name. */
if (l->l_info[DT_SONAME] != NULL)
{
/* Work around a kernel problem. The kernel cannot handle
addresses in the vsyscall DSO pages in writev() calls. */
const char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_SONAME]->d_un.d_val);
size_t len = strlen (dsoname) + 1;
char *copy = malloc (len);
if (copy == NULL)
_dl_fatal_printf ("out of memory\n");
l->l_libname->name = l->l_name = memcpy (copy, dsoname, len);
char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_SONAME]->d_un.d_val);
l->l_libname->name = dsoname;
l->l_name = dsoname;
}
/* Add the vDSO to the object list. */