Re: [PATCH][dizzy 1/6] glibc/wscanf: CVE-2015-1472

[akuster808 <akuster808@gmail.com>]

all in series merged to staging.

git@git.yoctoproject.org/poky-contrib.git akuster/dizzy-next

thanks,
Armin

On 12/14/2015 04:24 AM, Sona Sarmadi wrote:
> Fixes a heap buffer overflow in glibc wscanf.
> 
> References:
> https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-1472
> https://sourceware.org/ml/libc-alpha/2015-02/msg00119.html
> http://openwall.com/lists/oss-security/2015/02/04/1
> 
> Reference to upstream fix:
> https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commit;
> h=5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06
> 
> Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
> Signed-off-by: Tudor Florea <tudor.florea@enea.com>
> ---
>  ...5-1472-wscanf-allocates-too-little-memory.patch | 108 +++++++++++++++++++++
>  meta/recipes-core/glibc/glibc_2.20.bb              |   1 +
>  2 files changed, 109 insertions(+)
>  create mode 100644 meta/recipes-core/glibc/glibc/CVE-2015-1472-wscanf-allocates-too-little-memory.patch
> 
> diff --git a/meta/recipes-core/glibc/glibc/CVE-2015-1472-wscanf-allocates-too-little-memory.patch b/meta/recipes-core/glibc/glibc/CVE-2015-1472-wscanf-allocates-too-little-memory.patch
> new file mode 100644
> index 0000000..ab513aa
> --- /dev/null
> +++ b/meta/recipes-core/glibc/glibc/CVE-2015-1472-wscanf-allocates-too-little-memory.patch
> @@ -0,0 +1,108 @@
> +CVE-2015-1472: wscanf allocates too little memory
> +
> +BZ #16618
> +
> +Under certain conditions wscanf can allocate too little memory for the
> +to-be-scanned arguments and overflow the allocated buffer.  The
> +implementation now correctly computes the required buffer size when
> +using malloc.
> +
> +A regression test was added to tst-sscanf.
> +
> +Upstream-Status: Backport
> +
> +The patch is from (Paul Pluzhnikov <ppluzhnikov@google.com>):
> +[https://sourceware.org/git/?p=glibc.git;a=patch;h=5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06]
> +
> +diff -ruN a/ChangeLog b/ChangeLog
> +--- a/ChangeLog	2015-09-22 10:20:14.399408389 +0200
> ++++ b/ChangeLog	2015-09-22 10:33:07.374388595 +0200
> +@@ -1,3 +1,12 @@
> ++2015-02-05  Paul Pluzhnikov  <ppluzhnikov@google.com>
> ++
> ++       [BZ #16618] CVE-2015-1472
> ++       * stdio-common/tst-sscanf.c (main): Test for buffer overflow.
> ++       * stdio-common/vfscanf.c (_IO_vfscanf_internal): Compute needed
> ++       size in bytes. Store needed elements in wpmax. Use needed size
> ++       in bytes for extend_alloca.
> ++
> ++
> + 2014-12-16  Florian Weimer  <fweimer@redhat.com>
> + 
> +        [BZ #17630]
> +diff -ruN a/stdio-common/tst-sscanf.c b/stdio-common/tst-sscanf.c
> +--- a/stdio-common/tst-sscanf.c	2015-09-22 10:20:09.995596201 +0200
> ++++ b/stdio-common/tst-sscanf.c	2015-09-22 10:21:39.211791399 +0200
> +@@ -233,5 +233,38 @@
> + 	}
> +     }
> + 
> ++  /* BZ #16618
> ++     The test will segfault during SSCANF if the buffer overflow
> ++     is not fixed.  The size of `s` is such that it forces the use
> ++     of malloc internally and this triggers the incorrect computation.
> ++     Thus the value for SIZE is arbitrariy high enough that malloc
> ++     is used.  */
> ++  {
> ++#define SIZE 131072
> ++    CHAR *s = malloc ((SIZE + 1) * sizeof (*s));
> ++    if (s == NULL)
> ++      abort ();
> ++    for (size_t i = 0; i < SIZE; i++)
> ++      s[i] = L('0');
> ++    s[SIZE] = L('\0');
> ++    int i = 42;
> ++    /* Scan multi-digit zero into `i`.  */
> ++    if (SSCANF (s, L("%d"), &i) != 1)
> ++      {
> ++	printf ("FAIL: bug16618: SSCANF did not read one input item.\n");
> ++	result = 1;
> ++      }
> ++    if (i != 0)
> ++      {
> ++	printf ("FAIL: bug16618: Value of `i` was not zero as expected.\n");
> ++	result = 1;
> ++      }
> ++    free (s);
> ++    if (result != 1)
> ++      printf ("PASS: bug16618: Did not crash.\n");
> ++#undef SIZE
> ++  }
> ++
> ++
> +   return result;
> + }
> +diff -ruN a/stdio-common/vfscanf.c b/stdio-common/vfscanf.c
> +--- a/stdio-common/vfscanf.c	2015-09-22 10:20:14.051423230 +0200
> ++++ b/stdio-common/vfscanf.c	2015-09-22 10:21:39.215791228 +0200
> +@@ -279,9 +279,10 @@
> +       if (__glibc_unlikely (wpsize == wpmax))				      \
> + 	{								    \
> + 	  CHAR_T *old = wp;						    \
> +-	  size_t newsize = (UCHAR_MAX + 1 > 2 * wpmax			    \
> +-			    ? UCHAR_MAX + 1 : 2 * wpmax);		    \
> +-	  if (use_malloc || !__libc_use_alloca (newsize))		    \
> ++	  bool fits = __glibc_likely (wpmax <= SIZE_MAX / sizeof (CHAR_T) / 2); \
> ++	  size_t wpneed = MAX (UCHAR_MAX + 1, 2 * wpmax);		    \
> ++	  size_t newsize = fits ? wpneed * sizeof (CHAR_T) : SIZE_MAX;	    \
> ++	  if (!__libc_use_alloca (newsize))				    \
> + 	    {								    \
> + 	      wp = realloc (use_malloc ? wp : NULL, newsize);		    \
> + 	      if (wp == NULL)						    \
> +@@ -293,14 +294,13 @@
> + 		}							    \
> + 	      if (! use_malloc)						    \
> + 		MEMCPY (wp, old, wpsize);				    \
> +-	      wpmax = newsize;						    \
> ++	      wpmax = wpneed;						    \
> + 	      use_malloc = true;					    \
> + 	    }								    \
> + 	  else								    \
> + 	    {								    \
> + 	      size_t s = wpmax * sizeof (CHAR_T);			    \
> +-	      wp = (CHAR_T *) extend_alloca (wp, s,			    \
> +-					     newsize * sizeof (CHAR_T));    \
> ++	      wp = (CHAR_T *) extend_alloca (wp, s, newsize);		    \
> + 	      wpmax = s / sizeof (CHAR_T);				    \
> + 	      if (old != NULL)						    \
> + 		MEMCPY (wp, old, wpsize);				    \
> diff --git a/meta/recipes-core/glibc/glibc_2.20.bb b/meta/recipes-core/glibc/glibc_2.20.bb
> index a0736cd..cfbc1c2 100644
> --- a/meta/recipes-core/glibc/glibc_2.20.bb
> +++ b/meta/recipes-core/glibc/glibc_2.20.bb
> @@ -48,6 +48,7 @@ CVEPATCHES = "\
>          file://CVE-2014-7817-wordexp-fails-to-honour-WRDE_NOCMD.patch \
>          file://CVE-2012-3406-Stack-overflow-in-vfprintf-BZ-16617.patch \
>          file://CVE-2014-9402_endless-loop-in-getaddr_r.patch \
> +        file://CVE-2015-1472-wscanf-allocates-too-little-memory.patch \
>      "
>  LIC_FILES_CHKSUM = "file://LICENSES;md5=e9a558e243b36d3209f380deb394b213 \
>        file://COPYING;md5=b234ee4d69f5fce4486a80fdaf4a4263 \
>