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glibc: add upstream security patches fixing CVE-2017-1000366 (stack clash) 

glibc contains a vulnerability that allows specially crafted LD_LIBRARY_PATH
values to manipulate the heap/stack, causing them to alias, potentially
resulting in arbitrary code execution.  Please note that additional
hardening changes have been made to glibc to prevent manipulation of stack
and heap memory but these issues are not directly exploitable, as such they
have not been given a CVE.

https://www.qualys.com/2017/06/19/stack-clash/stack-clash.txt

Patches are identical to upstream, except that the ChangeLog modifications
have been stripped.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2017.08.x
Peter Korsgaard 2017-06-27 08:42:09 +02:00
parent 8398230bc7
commit c87fdfb605
3 changed files with 361 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
package/glibc/0002-CVE-2017-1000366-Ignore-LD_LIBRARY_PATH-for-AT_SECUR.patch 100644
View File

@ -0,0 +1,35 @@
From f6110a8fee2ca36f8e2d2abecf3cba9fa7b8ea7d Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Mon, 19 Jun 2017 17:09:55 +0200
Subject: [PATCH] CVE-2017-1000366: Ignore LD_LIBRARY_PATH for AT_SECURE=1
programs [BZ #21624]
LD_LIBRARY_PATH can only be used to reorder system search paths, which
is not useful functionality.
This makes an exploitable unbounded alloca in _dl_init_paths unreachable
for AT_SECURE=1 programs.
[Peter: Drop ChangeLog modification]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
elf/rtld.c | 3 ++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/elf/rtld.c b/elf/rtld.c
index 2446a87680..2269dbec81 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2422,7 +2422,8 @@ process_envvars (enum mode *modep)
case 12:
/* The library search path. */
- if (memcmp (envline, "LIBRARY_PATH", 12) == 0)
+ if (!__libc_enable_secure
+ && memcmp (envline, "LIBRARY_PATH", 12) == 0)
{
library_path = &envline[13];
break;
--
2.11.0

122
package/glibc/0003-ld.so-Reject-overly-long-LD_PRELOAD-path-elements.patch 100644
View File

@ -0,0 +1,122 @@
From 6d0ba622891bed9d8394eef1935add53003b12e8 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Mon, 19 Jun 2017 22:31:04 +0200
Subject: [PATCH] ld.so: Reject overly long LD_PRELOAD path elements
[Peter: Drop ChangeLog modification]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
elf/rtld.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 72 insertions(+), 16 deletions(-)
diff --git a/elf/rtld.c b/elf/rtld.c
index 2269dbec81..86ae20c83f 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -99,6 +99,35 @@ uintptr_t __pointer_chk_guard_local
strong_alias (__pointer_chk_guard_local, __pointer_chk_guard)
#endif
+/* Length limits for names and paths, to protect the dynamic linker,
+ particularly when __libc_enable_secure is active. */
+#ifdef NAME_MAX
+# define SECURE_NAME_LIMIT NAME_MAX
+#else
+# define SECURE_NAME_LIMIT 255
+#endif
+#ifdef PATH_MAX
+# define SECURE_PATH_LIMIT PATH_MAX
+#else
+# define SECURE_PATH_LIMIT 1024
+#endif
+
+/* Check that AT_SECURE=0, or that the passed name does not contain
+ directories and is not overly long. Reject empty names
+ unconditionally. */
+static bool
+dso_name_valid_for_suid (const char *p)
+{
+ if (__glibc_unlikely (__libc_enable_secure))
+ {
+ /* Ignore pathnames with directories for AT_SECURE=1
+ programs, and also skip overlong names. */
+ size_t len = strlen (p);
+ if (len >= SECURE_NAME_LIMIT || memchr (p, '/', len) != NULL)
+ return false;
+ }
+ return *p != '\0';
+}
/* List of auditing DSOs. */
static struct audit_list
@@ -718,6 +747,42 @@ static const char *preloadlist attribute_relro;
/* Nonzero if information about versions has to be printed. */
static int version_info attribute_relro;
+/* The LD_PRELOAD environment variable gives list of libraries
+ separated by white space or colons that are loaded before the
+ executable's dependencies and prepended to the global scope list.
+ (If the binary is running setuid all elements containing a '/' are
+ ignored since it is insecure.) Return the number of preloads
+ performed. */
+unsigned int
+handle_ld_preload (const char *preloadlist, struct link_map *main_map)
+{
+ unsigned int npreloads = 0;
+ const char *p = preloadlist;
+ char fname[SECURE_PATH_LIMIT];
+
+ while (*p != '\0')
+ {
+ /* Split preload list at space/colon. */
+ size_t len = strcspn (p, " :");
+ if (len > 0 && len < sizeof (fname))
+ {
+ memcpy (fname, p, len);
+ fname[len] = '\0';
+ }
+ else
+ fname[0] = '\0';
+
+ /* Skip over the substring and the following delimiter. */
+ p += len;
+ if (*p != '\0')
+ ++p;
+
+ if (dso_name_valid_for_suid (fname))
+ npreloads += do_preload (fname, main_map, "LD_PRELOAD");
+ }
+ return npreloads;
+}
+
static void
dl_main (const ElfW(Phdr) *phdr,
ElfW(Word) phnum,
@@ -1464,23 +1529,8 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
if (__glibc_unlikely (preloadlist != NULL))
{
- /* The LD_PRELOAD environment variable gives list of libraries
- separated by white space or colons that are loaded before the
- executable's dependencies and prepended to the global scope
- list. If the binary is running setuid all elements
- containing a '/' are ignored since it is insecure. */
- char *list = strdupa (preloadlist);
- char *p;
-
HP_TIMING_NOW (start);
-
- /* Prevent optimizing strsep. Speed is not important here. */
- while ((p = (strsep) (&list, " :")) != NULL)
- if (p[0] != '\0'
- && (__builtin_expect (! __libc_enable_secure, 1)
- || strchr (p, '/') == NULL))
- npreloads += do_preload (p, main_map, "LD_PRELOAD");
-
+ npreloads += handle_ld_preload (preloadlist, main_map);
HP_TIMING_NOW (stop);
HP_TIMING_DIFF (diff, start, stop);
HP_TIMING_ACCUM_NT (load_time, diff);
--
2.11.0

204
package/glibc/0004-ld.so-Reject-overly-long-LD_AUDIT-path-elements.patch 100644
View File

@ -0,0 +1,204 @@
From 81b82fb966ffbd94353f793ad17116c6088dedd9 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Mon, 19 Jun 2017 22:32:12 +0200
Subject: [PATCH] ld.so: Reject overly long LD_AUDIT path elements
Also only process the last LD_AUDIT entry.
[Peter: Drop ChangeLog modification]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
elf/rtld.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 105 insertions(+), 15 deletions(-)
diff --git a/elf/rtld.c b/elf/rtld.c
index 86ae20c83f..65647fb1c8 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -129,13 +129,91 @@ dso_name_valid_for_suid (const char *p)
return *p != '\0';
}
-/* List of auditing DSOs. */
+/* LD_AUDIT variable contents. Must be processed before the
+ audit_list below. */
+const char *audit_list_string;
+
+/* Cyclic list of auditing DSOs. audit_list->next is the first
+ element. */
static struct audit_list
{
const char *name;
struct audit_list *next;
} *audit_list;
+/* Iterator for audit_list_string followed by audit_list. */
+struct audit_list_iter
+{
+ /* Tail of audit_list_string still needing processing, or NULL. */
+ const char *audit_list_tail;
+
+ /* The list element returned in the previous iteration. NULL before
+ the first element. */
+ struct audit_list *previous;
+
+ /* Scratch buffer for returning a name which is part of
+ audit_list_string. */
+ char fname[SECURE_NAME_LIMIT];
+};
+
+/* Initialize an audit list iterator. */
+static void
+audit_list_iter_init (struct audit_list_iter *iter)
+{
+ iter->audit_list_tail = audit_list_string;
+ iter->previous = NULL;
+}
+
+/* Iterate through both audit_list_string and audit_list. */
+static const char *
+audit_list_iter_next (struct audit_list_iter *iter)
+{
+ if (iter->audit_list_tail != NULL)
+ {
+ /* First iterate over audit_list_string. */
+ while (*iter->audit_list_tail != '\0')
+ {
+ /* Split audit list at colon. */
+ size_t len = strcspn (iter->audit_list_tail, ":");
+ if (len > 0 && len < sizeof (iter->fname))
+ {
+ memcpy (iter->fname, iter->audit_list_tail, len);
+ iter->fname[len] = '\0';
+ }
+ else
+ /* Do not return this name to the caller. */
+ iter->fname[0] = '\0';
+
+ /* Skip over the substring and the following delimiter. */
+ iter->audit_list_tail += len;
+ if (*iter->audit_list_tail == ':')
+ ++iter->audit_list_tail;
+
+ /* If the name is valid, return it. */
+ if (dso_name_valid_for_suid (iter->fname))
+ return iter->fname;
+ /* Otherwise, wrap around and try the next name. */
+ }
+ /* Fall through to the procesing of audit_list. */
+ }
+
+ if (iter->previous == NULL)
+ {
+ if (audit_list == NULL)
+ /* No pre-parsed audit list. */
+ return NULL;
+ /* Start of audit list. The first list element is at
+ audit_list->next (cyclic list). */
+ iter->previous = audit_list->next;
+ return iter->previous->name;
+ }
+ if (iter->previous == audit_list)
+ /* Cyclic list wrap-around. */
+ return NULL;
+ iter->previous = iter->previous->next;
+ return iter->previous->name;
+}
+
#ifndef HAVE_INLINED_SYSCALLS
/* Set nonzero during loading and initialization of executable and
libraries, cleared before the executable's entry point runs. This
@@ -1305,11 +1383,13 @@ of this helper program; chances are you did not intend to run this program.\n\
GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
/* If we have auditing DSOs to load, do it now. */
- if (__glibc_unlikely (audit_list != NULL))
+ bool need_security_init = true;
+ if (__glibc_unlikely (audit_list != NULL)
+ || __glibc_unlikely (audit_list_string != NULL))
{
- /* Iterate over all entries in the list. The order is important. */
struct audit_ifaces *last_audit = NULL;
- struct audit_list *al = audit_list->next;
+ struct audit_list_iter al_iter;
+ audit_list_iter_init (&al_iter);
/* Since we start using the auditing DSOs right away we need to
initialize the data structures now. */
@@ -1320,9 +1400,14 @@ of this helper program; chances are you did not intend to run this program.\n\
use different values (especially the pointer guard) and will
fail later on. */
security_init ();
+ need_security_init = false;
- do
+ while (true)
{
+ const char *name = audit_list_iter_next (&al_iter);
+ if (name == NULL)
+ break;
+
int tls_idx = GL(dl_tls_max_dtv_idx);
/* Now it is time to determine the layout of the static TLS
@@ -1331,7 +1416,7 @@ of this helper program; chances are you did not intend to run this program.\n\
no DF_STATIC_TLS bit is set. The reason is that we know
glibc will use the static model. */
struct dlmopen_args dlmargs;
- dlmargs.fname = al->name;
+ dlmargs.fname = name;
dlmargs.map = NULL;
const char *objname;
@@ -1344,7 +1429,7 @@ of this helper program; chances are you did not intend to run this program.\n\
not_loaded:
_dl_error_printf ("\
ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
- al->name, err_str);
+ name, err_str);
if (malloced)
free ((char *) err_str);
}
@@ -1448,10 +1533,7 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
goto not_loaded;
}
}
-
- al = al->next;
}
- while (al != audit_list->next);
/* If we have any auditing modules, announce that we already
have two objects loaded. */
@@ -1715,7 +1797,7 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
if (tcbp == NULL)
tcbp = init_tls ();
- if (__glibc_likely (audit_list == NULL))
+ if (__glibc_likely (need_security_init))
/* Initialize security features. But only if we have not done it
earlier. */
security_init ();
@@ -2346,9 +2428,7 @@ process_dl_audit (char *str)
char *p;
while ((p = (strsep) (&str, ":")) != NULL)
- if (p[0] != '\0'
- && (__builtin_expect (! __libc_enable_secure, 1)
- || strchr (p, '/') == NULL))
+ if (dso_name_valid_for_suid (p))
{
/* This is using the local malloc, not the system malloc. The
memory can never be freed. */
@@ -2412,7 +2492,7 @@ process_envvars (enum mode *modep)
break;
}
if (memcmp (envline, "AUDIT", 5) == 0)
- process_dl_audit (&envline[6]);
+ audit_list_string = &envline[6];
break;
case 7:
--
2.11.0