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CVE-2023-4911 glibc: buffer overflow in ld.so leading to privilege escalation (RHEL-3000)

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Resolves: RHEL-3000
Reviewed-by: Siddhesh Poyarekar <siddhesh@redhat.com>
This commit is contained in:
Carlos O'Donell 2023-09-19 16:55:07 -04:00
parent 3f7d8c721a
commit d9eb6f4246
2 changed files with 169 additions and 1 deletions
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164
glibc-RHEL-3000.patch Normal file
View File

@ -0,0 +1,164 @@
This patch was developed under embargo and cannot reference an upstream
commit. To find the associated commit please review the upstream git
log for CVE-2023-4911 to identify the relevant commits.
Author: Siddhesh Poyarekar <siddhesh@redhat.com>
Date: Tue Sep 19 11:52:44 2023 -0400
tunables: Terminate if end of input is reached (CVE-2023-4911)
The string parsing routine may end up writing beyond bounds of tunestr
if the input tunable string is malformed, of the form name=name=val.
This gets processed twice, first as name=name=val and next as name=val,
resulting in tunestr being name=name=val:name=val, thus overflowing
tunestr.
Terminate the parsing loop at the first instance itself so that tunestr
does not overflow.
This also fixes up tst-env-setuid-tunables to actually handle failures
correct and add new tests to validate the fix for this CVE.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
---
Tested on x86_64.
NEWS | 5 +++++
elf/dl-tunables.c | 17 ++++++++++-------
elf/tst-env-setuid-tunables.c | 36 +++++++++++++++++++++++++++--------
3 files changed, 43 insertions(+), 15 deletions(-)
Conflicts:
NEWS
(Dropped)
elf/tst-env-setuid-tunables.c
(Trivial HAVE_TUNABLES conflict)
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 8009e54ee5db32be..837474b5044cb5d7 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -188,11 +188,7 @@ parse_tunables (char *tunestr, char *valstring)
/* If we reach the end of the string before getting a valid name-value
pair, bail out. */
if (p[len] == '\0')
- {
- if (__libc_enable_secure)
- tunestr[off] = '\0';
- return;
- }
+ break;
/* We did not find a valid name-value pair before encountering the
colon. */
@@ -252,9 +248,16 @@ parse_tunables (char *tunestr, char *valstring)
}
}
- if (p[len] != '\0')
- p += len + 1;
+ /* We reached the end while processing the tunable string. */
+ if (p[len] == '\0')
+ break;
+
+ p += len + 1;
}
+
+ /* Terminate tunestr before we leave. */
+ if (__libc_enable_secure)
+ tunestr[off] = '\0';
}
#endif
diff --git a/elf/tst-env-setuid-tunables.c b/elf/tst-env-setuid-tunables.c
index 05619c9adc8b2698..cd4e84364074c613 100644
--- a/elf/tst-env-setuid-tunables.c
+++ b/elf/tst-env-setuid-tunables.c
@@ -52,6 +52,8 @@ const char *teststrings[] =
"glibc.malloc.perturb=0x800:not_valid.malloc.check=2:glibc.malloc.mmap_threshold=4096",
"glibc.not_valid.check=2:glibc.malloc.mmap_threshold=4096",
"not_valid.malloc.check=2:glibc.malloc.mmap_threshold=4096",
+ "glibc.malloc.mmap_threshold=glibc.malloc.mmap_threshold=4096",
+ "glibc.malloc.check=2",
"glibc.malloc.garbage=2:glibc.maoc.mmap_threshold=4096:glibc.malloc.check=2",
"glibc.malloc.check=4:glibc.malloc.garbage=2:glibc.maoc.mmap_threshold=4096",
":glibc.malloc.garbage=2:glibc.malloc.check=1",
@@ -70,6 +72,8 @@ const char *resultstrings[] =
"glibc.malloc.perturb=0x800:glibc.malloc.mmap_threshold=4096",
"glibc.malloc.mmap_threshold=4096",
"glibc.malloc.mmap_threshold=4096",
+ "glibc.malloc.mmap_threshold=glibc.malloc.mmap_threshold=4096",
+ "",
"",
"",
"",
@@ -84,11 +88,18 @@ test_child (int off)
const char *val = getenv ("GLIBC_TUNABLES");
#if HAVE_TUNABLES
+ printf (" [%d] GLIBC_TUNABLES is %s\n", off, val);
+ fflush (stdout);
if (val != NULL && strcmp (val, resultstrings[off]) == 0)
return 0;
if (val != NULL)
- printf ("[%d] Unexpected GLIBC_TUNABLES VALUE %s\n", off, val);
+ printf (" [%d] Unexpected GLIBC_TUNABLES VALUE %s, expected %s\n",
+ off, val, resultstrings[off]);
+ else
+ printf (" [%d] GLIBC_TUNABLES environment variable absent\n", off);
+
+ fflush (stdout);
return 1;
#else
@@ -117,21 +128,26 @@ do_test (int argc, char **argv)
if (ret != 0)
exit (1);
- exit (EXIT_SUCCESS);
+ /* Special return code to make sure that the child executed all the way
+ through. */
+ exit (42);
}
else
{
- int ret = 0;
-
/* Spawn tests. */
for (int i = 0; i < array_length (teststrings); i++)
{
char buf[INT_BUFSIZE_BOUND (int)];
- printf ("Spawned test for %s (%d)\n", teststrings[i], i);
+ printf ("[%d] Spawned test for %s\n", i, teststrings[i]);
snprintf (buf, sizeof (buf), "%d\n", i);
+ fflush (stdout);
if (setenv ("GLIBC_TUNABLES", teststrings[i], 1) != 0)
- exit (1);
+ {
+ printf (" [%d] Failed to set GLIBC_TUNABLES: %m", i);
+ support_record_failure ();
+ continue;
+ }
int status = support_capture_subprogram_self_sgid (buf);
@@ -139,9 +155,14 @@ do_test (int argc, char **argv)
if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
return EXIT_UNSUPPORTED;
- ret |= status;
+ if (WEXITSTATUS (status) != 42)
+ {
+ printf (" [%d] child failed with status %d\n", i,
+ WEXITSTATUS (status));
+ support_record_failure ();
+ }
}
- return ret;
+ return 0;
}
}

6
glibc.spec
View File

@ -155,7 +155,7 @@ end \
Summary: The GNU libc libraries
Name: glibc
Version: %{glibcversion}
Release: 83%{?dist}.5
Release: 83%{?dist}.6
# In general, GPLv2+ is used by programs, LGPLv2+ is used for
# libraries.
@ -767,6 +767,7 @@ Patch530: glibc-RHEL-2426-10.patch
Patch531: glibc-RHEL-2426-11.patch
Patch532: glibc-RHEL-2426-12.patch
Patch533: glibc-RHEL-2426-13.patch
Patch534: glibc-RHEL-3000.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -2924,6 +2925,9 @@ update_gconv_modules_cache ()
%endif
%changelog
* Tue Sep 19 2023 Carlos O'Donell <carlos@redhat.com> - 2.34-83.6
- CVE-2023-4911 glibc: buffer overflow in ld.so leading to privilege escalation (RHEL-3000)
* Tue Sep 19 2023 Florian Weimer <fweimer@redhat.com> - 2.34-83.5
- Revert: Always call destructors in reverse constructor order (RHEL-2491)