From: Jakub Jelinek <jakub@redhat.com>
To: Ulrich Drepper <drepper@redhat.com>
Cc: Glibc hackers <libc-hacker@sources.redhat.com>, mingo@redhat.com
Subject: [PATCH] vDSO fixes
Date: Thu, 26 Feb 2004 17:26:00 -0000 [thread overview]
Message-ID: <20040226151734.GK4581@sunsite.ms.mff.cuni.cz> (raw)
Hi!
This patch fixes 3 problems with vDSOs:
1) assertion failure if AT_SYSINFO_EHDR is passed to ld.so and
one runs e.g. elf/ld.so ./libc.so
(the code needs to take into account the vDSO which is in the
dl_loaded chain, yet not in the search list
2) if AT_SYSINFO has been passed to the app, IMHO ld.so should honor it,
not unconditionally overwrite it with e_entry of the vDSO pointed
by AT_SYSINFO_EHDR
3) ld.so did not handle randomized vDSO properly (although there is code
which handles relocation of .dynamic in such cases,
a) e_entry for GL(dl_sysinfo) has not been adjusted
b) l_addr and l_map_end have not been computed properly
c) there was an assertion that l_addr is 0)
To test this (don't have a kernel with randomized vDSO yet), I added
open/mmap/close of vsyscall.so into dl-sysdep.c and tweaked
GL(dl_sysinfo_dso) and GL(dl_sysinfo) accordingly (on AMD64 for 32-bit app,
and syscall insn doesn't need fixed return address, so I did not need
kernel changes).
2004-02-26 Jakub Jelinek <jakub@redhat.com>
* elf/rtld.c (dl_main): Correctly set up l_map_end and l_addr
in vDSO's link_map, don't assume l_addr == 0. Set GL(dl_sysinfo)
from e_entry only if AT_SYSINFO not present and adjust by l_addr.
Take vDSO into account when inserting rtld into _dl_loaded chain.
--- libc/elf/rtld.c 20 Feb 2004 05:40:40 -0000 1.313
+++ libc/elf/rtld.c 26 Feb 2004 17:02:38 -0000
@@ -1211,11 +1211,9 @@ ERROR: ld.so: object '%s' from %s cannot
}
#ifdef NEED_DL_SYSINFO
+ struct link_map *sysinfo_map = NULL;
if (GL(dl_sysinfo_dso) != NULL)
{
- /* We have a prelinked DSO preloaded by the system. */
- GL(dl_sysinfo) = GL(dl_sysinfo_dso)->e_entry;
-
/* Do an abridged version of the work _dl_map_object_from_fd would do
to map in the object. It's already mapped and prelinked (and
better be, since it's read-only and so we couldn't relocate it).
@@ -1225,9 +1223,6 @@ ERROR: ld.so: object '%s' from %s cannot
if (__builtin_expect (l != NULL, 1))
{
static ElfW(Dyn) dyn_temp[DL_RO_DYN_TEMP_CNT];
-#ifndef NDEBUG
- uint_fast16_t pt_load_num = 0;
-#endif
l->l_phdr = ((const void *) GL(dl_sysinfo_dso)
+ GL(dl_sysinfo_dso)->e_phoff);
@@ -1239,21 +1234,21 @@ ERROR: ld.so: object '%s' from %s cannot
{
l->l_ld = (void *) ph->p_vaddr;
l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn));
- break;
}
-#ifndef NDEBUG
- if (ph->p_type == PT_LOAD)
+ else if (ph->p_type == PT_LOAD)
{
- assert (pt_load_num
- || (void *) ph->p_vaddr == GL(dl_sysinfo_dso));
- pt_load_num++;
+ if (! l->l_addr)
+ l->l_addr = ph->p_vaddr;
+ else if (ph->p_vaddr + ph->p_memsz >= l->l_map_end)
+ l->l_map_end = ph->p_vaddr + ph->p_memsz;
}
-#endif
}
+ l->l_map_start = (ElfW(Addr)) GL(dl_sysinfo_dso);
+ l->l_addr = l->l_map_start - l->l_addr;
+ l->l_map_end += l->l_addr;
elf_get_dynamic_info (l, dyn_temp);
_dl_setup_hash (l);
l->l_relocated = 1;
- l->l_map_start = (ElfW(Addr)) GL(dl_sysinfo_dso);
/* 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
@@ -1271,6 +1266,11 @@ ERROR: ld.so: object '%s' from %s cannot
_dl_fatal_printf ("out of memory\n");
l->l_libname->name = memcpy (copy, dsoname, len);
}
+
+ /* We have a prelinked DSO preloaded by the system. */
+ if (GL(dl_sysinfo) == DL_SYSINFO_DEFAULT)
+ GL(dl_sysinfo) = GL(dl_sysinfo_dso)->e_entry + l->l_addr;
+ sysinfo_map = l;
}
}
#endif
@@ -1316,9 +1316,17 @@ ERROR: ld.so: object '%s' from %s cannot
++i;
GL(dl_rtld_map).l_prev = GL(dl_loaded)->l_searchlist.r_list[i - 1];
if (__builtin_expect (mode, normal) == normal)
- GL(dl_rtld_map).l_next = (i + 1 < GL(dl_loaded)->l_searchlist.r_nlist
- ? GL(dl_loaded)->l_searchlist.r_list[i + 1]
- : NULL);
+ {
+ GL(dl_rtld_map).l_next = (i + 1 < GL(dl_loaded)->l_searchlist.r_nlist
+ ? GL(dl_loaded)->l_searchlist.r_list[i + 1]
+ : NULL);
+#ifdef NEED_DL_SYSINFO
+ if (sysinfo_map != NULL
+ && GL(dl_rtld_map).l_prev->l_next == sysinfo_map
+ && GL(dl_rtld_map).l_next != sysinfo_map)
+ GL(dl_rtld_map).l_prev = sysinfo_map;
+#endif
+ }
else
/* In trace mode there might be an invisible object (which we
could not find) after the previous one in the search list.
Jakub
next reply other threads:[~2004-02-26 17:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-26 17:26 Jakub Jelinek [this message]
2004-02-26 20:08 ` Ulrich Drepper
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20040226151734.GK4581@sunsite.ms.mff.cuni.cz \
--to=jakub@redhat.com \
--cc=drepper@redhat.com \
--cc=libc-hacker@sources.redhat.com \
--cc=mingo@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).