Re: [PR PATCH] [Updated] glibc: backport patch to fix CVE-2023-4911

[Johnnynator <Johnnynator@users.noreply.github.com>]

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There is an updated pull request by Johnnynator against master on the void-packages repository

https://github.com/Johnnynator/void-packages CVE-2023-4911
https://github.com/void-linux/void-packages/pull/46415

glibc: backport patch to fix CVE-2023-4911
https://lwn.net/ml/oss-security/20231003175031.GA16924@localhost.localdomain/


A patch file from https://github.com/void-linux/void-packages/pull/46415.patch is attached

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From 6b20f8066379a235cd75218a538d57fb6dce8aea Mon Sep 17 00:00:00 2001
From: John <me@johnnynator.dev>
Date: Tue, 3 Oct 2023 22:08:47 +0200
Subject: [PATCH] glibc: backport patch to fix CVE-2023-4911

https://lwn.net/ml/oss-security/20231003175031.GA16924@localhost.localdomain/
---
 ...te-GLIBC_TUNABLES-in-setxid-binaries.patch | 205 ++++++++++++++++++
 srcpkgs/glibc/template                        |   2 +-
 2 files changed, 206 insertions(+), 1 deletion(-)
 create mode 100644 srcpkgs/glibc/patches/committed-1-2-Propagate-GLIBC_TUNABLES-in-setxid-binaries.patch

diff --git a/srcpkgs/glibc/patches/committed-1-2-Propagate-GLIBC_TUNABLES-in-setxid-binaries.patch b/srcpkgs/glibc/patches/committed-1-2-Propagate-GLIBC_TUNABLES-in-setxid-binaries.patch
new file mode 100644
index 0000000000000..31e1a2048eaf4
--- /dev/null
+++ b/srcpkgs/glibc/patches/committed-1-2-Propagate-GLIBC_TUNABLES-in-setxid-binaries.patch
@@ -0,0 +1,205 @@
+From: Siddhesh Poyarekar <siddhesh@sourceware.org>
+Subject: [committed 1/2] Propagate GLIBC_TUNABLES in setxid binaries
+Date: Tue,  3 Oct 2023 13:08:10 -0400
+
+GLIBC_TUNABLES scrubbing happens earlier than envvar scrubbing and some
+tunables are required to propagate past setxid boundary, like their
+env_alias.  Rely on tunable scrubbing to clean out GLIBC_TUNABLES like
+before, restoring behaviour in glibc 2.37 and earlier.
+
+Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
+Reviewed-by: Carlos O'Donell <carlos@redhat.com>
+---
+ sysdeps/generic/unsecvars.h | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h
+index 81397fb90b..8278c50a84 100644
+--- a/sysdeps/generic/unsecvars.h
++++ b/sysdeps/generic/unsecvars.h
+@@ -1,16 +1,9 @@
+-#if !HAVE_TUNABLES
+-# define GLIBC_TUNABLES_ENVVAR "GLIBC_TUNABLES\0"
+-#else
+-# define GLIBC_TUNABLES_ENVVAR
+-#endif
+-
+ /* Environment variable to be removed for SUID programs.  The names are
+    all stuffed in a single string which means they have to be terminated
+    with a '\0' explicitly.  */
+ #define UNSECURE_ENVVARS \
+   "GCONV_PATH\0"							      \
+   "GETCONF_DIR\0"							      \
+-  GLIBC_TUNABLES_ENVVAR							      \
+   "HOSTALIASES\0"							      \
+   "LD_AUDIT\0"								      \
+   "LD_DEBUG\0"								      \
+
+From: Siddhesh Poyarekar <siddhesh@sourceware.org>
+Subject: [committed 2/2] tunables: Terminate if end of input is reached
+ (CVE-2023-4911)
+Date: Tue,  3 Oct 2023 13:08:11 -0400
+
+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>
+---
+ NEWS                          |  5 +++++
+ elf/dl-tunables.c             | 17 +++++++++-------
+ elf/tst-env-setuid-tunables.c | 37 +++++++++++++++++++++++++++--------
+ 3 files changed, 44 insertions(+), 15 deletions(-)
+
+diff --git a/NEWS b/NEWS
+index a94650da64..cc4b81f0ac 100644
+--- a/NEWS
++++ b/NEWS
+@@ -64,6 +64,11 @@ Security related changes:
+   an application calls getaddrinfo for AF_INET6 with AI_CANONNAME,
+   AI_ALL and AI_V4MAPPED flags set.
+ 
++  CVE-2023-4911: If a tunable of the form NAME=NAME=VAL is passed in the
++  environment of a setuid program and NAME is valid, it may result in a
++  buffer overflow, which could be exploited to achieve escalated
++  privileges.  This flaw was introduced in glibc 2.34.
++
+ The following bugs are resolved with this release:
+ 
+   [The release manager will add the list generated by
+diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
+index 62b7332d95..cae67efa0a 100644
+--- a/elf/dl-tunables.c
++++ b/elf/dl-tunables.c
+@@ -180,11 +180,7 @@ 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.  */
+@@ -244,9 +240,16 @@ 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';
+ }
+ 
+ /* Enable the glibc.malloc.check tunable in SETUID/SETGID programs only when
+diff --git a/elf/tst-env-setuid-tunables.c b/elf/tst-env-setuid-tunables.c
+index 7dfb0e073a..f0b92c97e7 100644
+--- a/elf/tst-env-setuid-tunables.c
++++ b/elf/tst-env-setuid-tunables.c
+@@ -50,6 +50,8 @@ 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",
+@@ -68,6 +70,8 @@ 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",
++  "",
+   "",
+   "",
+   "",
+@@ -88,11 +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
+@@ -106,21 +117,26 @@ 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);
+ 
+@@ -128,9 +144,14 @@ 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;
+     }
+ }
+ 
diff --git a/srcpkgs/glibc/template b/srcpkgs/glibc/template
index 452b55c127624..98de6ad7412ed 100644
--- a/srcpkgs/glibc/template
+++ b/srcpkgs/glibc/template
@@ -1,7 +1,7 @@
 # Template file for 'glibc'
 pkgname=glibc
 version=2.36
-revision=1
+revision=2
 _patchver="72-g0f90d6204d"
 bootstrap=yes
 short_desc="GNU C library"