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| author | Paul Pluzhnikov <ppluzhnikov@google.com> | 2015-02-06 00:30:42 -0500 |
|---|---|---|
| committer | Adhemerval Zanella <azanella@linux.vnet.ibm.com> | 2015-02-23 09:09:19 -0500 |
| commit | b5faf032c4c6a2260a9a93d8d4df611caa8b54cc (patch) | |
| tree | 6c21dd50664bece7fe4e8931b4ba80239f5f26b2 | |
| parent | 88a8a351f3a6a95205a1499fd68b79fc3d0b9d19 (diff) | |
| download | glibc-b5faf032c4c6a2260a9a93d8d4df611caa8b54cc.zip glibc-b5faf032c4c6a2260a9a93d8d4df611caa8b54cc.tar.gz glibc-b5faf032c4c6a2260a9a93d8d4df611caa8b54cc.tar.bz2 | |
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.
Conflicts:
ChangeLog
NEWS
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | NEWS | 5 | ||||
| -rw-r--r-- | stdio-common/tst-sscanf.c | 33 | ||||
| -rw-r--r-- | stdio-common/vfscanf.c | 12 |
4 files changed, 50 insertions, 8 deletions
@@ -1,3 +1,11 @@ +2015-02-05 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. + 2014-11-19 Carlos O'Donell <carlos@redhat.com> Florian Weimer <fweimer@redhat.com> Joseph Myers <joseph@codesourcery.com> @@ -9,8 +9,9 @@ Version 2.19.1 * The following bugs are resolved with this release: - 16545, 16617, 16683, 16689, 16701, 16706, 16707, 16739, 16815, 16619, - 16740, 17031, 17048, 17137, 17153, 17187, 17213, 17325, 17625, 17630. + 16545, 16617, 16618, 16683, 16689, 16701, 16706, 16707, 16739, 16815, + 16619, 16740, 17031, 17048, 17137, 17153, 17187, 17213, 17325, 17625, + 17630. * 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 1214c7d..c62bee6 100644 --- a/stdio-common/tst-sscanf.c +++ b/stdio-common/tst-sscanf.c @@ -232,5 +232,38 @@ 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 2e1e91a..d7a18e3 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 (__builtin_expect (wpsize == wpmax, 0)) \ { \ 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); \ |