fix CVE-2021-3999

(cherry picked from commit 29565817f88a630643f174796bc9f66b4643ca1f)

getcwd-Set-errno-to-ERANGE-for-size-1-CVE-2021-3999.patch

@@ -0,0 +1,70 @@
+From 472e799a5f2102bc0c3206dbd5a801765fceb39c Mon Sep 17 00:00:00 2001
+From: Siddhesh Poyarekar <siddhesh@sourceware.org>
+Date: Fri, 21 Jan 2022 23:32:56 +0530
+Subject: [PATCH] getcwd: Set errno to ERANGE for size == 1 (CVE-2021-3999)
+
+No valid path returned by getcwd would fit into 1 byte, so reject the
+size early and return NULL with errno set to ERANGE.  This change is
+prompted by CVE-2021-3999, which describes a single byte buffer
+underflow and overflow when all of the following conditions are met:
+
+- The buffer size (i.e. the second argument of getcwd) is 1 byte
+- The current working directory is too long
+- '/' is also mounted on the current working directory
+
+Sequence of events:
+
+- In sysdeps/unix/sysv/linux/getcwd.c, the syscall returns ENAMETOOLONG
+  because the linux kernel checks for name length before it checks
+  buffer size
+
+- The code falls back to the generic getcwd in sysdeps/posix
+
+- In the generic func, the buf[0] is set to '\0' on line 269
+
+- this while loop on line 282 is bypassed:
+
+    while (!(thisdev == rootdev && thisino == rootino))
+
+  since the rootfs (/) is bind mounted onto the directory and the flow
+  goes on to line 492, where it puts a '/' in the byte before the
+  buffer.
+
+- Finally on line 500, it moves 2 bytes (the underflowed byte and the
+  '\0') to the buf[0] and buf[1], resulting in a 1 byte buffer overflow.
+
+- buf is returned on line 514 and errno is not set.
+
+This resolves BZ #28769.
+
+Reviewed-by: Andreas Schwab <schwab@linux-m68k.org>
+Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+Signed-off-by: Qualys Security Advisory <qsa@qualys.com>
+Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
+(cherry picked from commit 23e0e8f5f1fb5ed150253d986ecccdc90c2dcd5e)
+---
+ sysdeps/posix/getcwd.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/sysdeps/posix/getcwd.c b/sysdeps/posix/getcwd.c
+index b53433a2..e3c1d77c 100644
+--- a/sysdeps/posix/getcwd.c
++++ b/sysdeps/posix/getcwd.c
+@@ -239,6 +239,14 @@ __getcwd (char *buf, size_t size)
+   int fd = AT_FDCWD;
+ 
+   char *path;
++
++  /* A size of 1 byte is never useful.  */
++  if (size == 1)
++    {
++      __set_errno (ERANGE);
++      return NULL;
++    }
++
+ #ifndef NO_ALLOCATION
+   size_t allocated = size;
+   if (size == 0)
+-- 
+2.27.0
+

glibc.spec

@@ -59,7 +59,7 @@
 ##############################################################################
 Name: 	 	glibc
 Version: 	2.28
-Release: 	86
+Release: 	87
 Summary: 	The GNU libc libraries
 License:	%{all_license}
 URL: 		http://www.gnu.org/software/glibc/
@@ -148,6 +148,7 @@ Patch64: socket-Add-the-__sockaddr_un_set-function.patch
 Patch65: CVE-2022-23219-Buffer-overflow-in-sunrpc-clnt_create.patch
 Patch66: sunrpc-Test-case-for-clnt_create-unix-buffer-overflo.patch
 Patch67: CVE-2022-23218-Buffer-overflow-in-sunrpc-svcunix_cre.patch
+Patch68: getcwd-Set-errno-to-ERANGE-for-size-1-CVE-2021-3999.patch
 
 Provides: ldconfig rtld(GNU_HASH) bundled(gnulib)
 
@@ -1172,10 +1173,13 @@ fi
 %doc hesiod/README.hesiod
 
 %changelog
-* Thu Jan 20 2021 Qingqing Li <liqingqing3@huawei.com> - 2.28-86
+* Tue Jan 25 2022 Qingqing Li <liqingqing3@huawei.com> - 2.28-87
+- fix CVE-2021-3999
+
+* Thu Jan 20 2022 Qingqing Li <liqingqing3@huawei.com> - 2.28-86
 - sunrpc: fix compile error
 
-* Wed Jan 19 2021 Qingqing Li <liqingqing3@huawei.com> - 2.28-85
+* Wed Jan 19 2022 Qingqing Li <liqingqing3@huawei.com> - 2.28-85
 - sunrpc: fix CVE-2022-23218 and fix CVE-2022-23219
 
 * Fri Dec 24 2021 Yang yanchao <yangyanchao6@huawei.com> - 2.28-84