aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorPaul Pluzhnikov <ppluzhnikov@google.com>2015-02-06 00:30:42 -0500
committerMike Frysinger <vapier@gentoo.org>2015-02-16 05:26:49 -0500
commit4d54424420c6300efbf57a7b9aa8635a8b8c1942 (patch)
treeb87845b3970fac459cae136a751a5c0e1f7816ca
parent1bf9d48aec087062e2a14b77cb5ee1fa81be334c (diff)
downloadtermbaud-4d54424420c6300efbf57a7b9aa8635a8b8c1942.tar.gz
termbaud-4d54424420c6300efbf57a7b9aa8635a8b8c1942.tar.xz
termbaud-4d54424420c6300efbf57a7b9aa8635a8b8c1942.zip
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. (cherry picked from commit 5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06) Conflicts: ChangeLog NEWS
-rw-r--r--ChangeLog8
-rw-r--r--NEWS9
-rw-r--r--stdio-common/tst-sscanf.c33
-rw-r--r--stdio-common/vfscanf.c12
4 files changed, 54 insertions, 8 deletions
diff --git a/ChangeLog b/ChangeLog
index a6461e6821e..ccce486c9d6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-02-16 Paul Pluzhnikov <ppluzhnikov@google.com>
+
+ [BZ #16618]
+ * 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.
+
2015-02-16 H.J. Lu <hongjiu.lu@intel.com>
[BZ #17801]
diff --git a/NEWS b/NEWS
index 0eb3fb3e7f0..976f2ea0236 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,13 @@ Version 2.20.1
* The following bugs are resolved with this release:
- 16009, 16617, 17266, 17370, 17371, 17460, 17485, 17555, 17625, 17630,
- 17801.
+ 16009, 16617, 16618, 17266, 17370, 17371, 17460, 17485, 17555, 17625,
+ 17630, 17801.
+
+* CVE-2015-1472 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.
* CVE-2104-7817 The wordexp function could ignore the WRDE_NOCMD flag
under certain input conditions resulting in the execution of a shell for
diff --git a/stdio-common/tst-sscanf.c b/stdio-common/tst-sscanf.c
index 9fef93a5357..6394fe1cccd 100644
--- a/stdio-common/tst-sscanf.c
+++ b/stdio-common/tst-sscanf.c
@@ -233,5 +233,38 @@ main (void)
}
}
+ /* 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 --git a/stdio-common/vfscanf.c b/stdio-common/vfscanf.c
index e0d224530cc..a4f06b44e57 100644
--- a/stdio-common/vfscanf.c
+++ b/stdio-common/vfscanf.c
@@ -272,9 +272,10 @@ _IO_vfscanf_internal (_IO_FILE *s, const char *format, _IO_va_list argptr,
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) \
@@ -286,14 +287,13 @@ _IO_vfscanf_internal (_IO_FILE *s, const char *format, _IO_va_list argptr,
} \
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); \