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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 10:00:32 -0500 |
| commit | 627eabb20f2b70faa3698e2c0124094c6d51af8e (patch) | |
| tree | 52a452489ef9c9b27f7d40bb39853e0781b5c164 | |
| parent | ec36394743c15fedca294219f2254b180c4e327c (diff) | |
| download | glibc-627eabb20f2b70faa3698e2c0124094c6d51af8e.tar.gz glibc-627eabb20f2b70faa3698e2c0124094c6d51af8e.tar.xz glibc-627eabb20f2b70faa3698e2c0124094c6d51af8e.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. Conflicts: ChangeLog NEWS stdio-common/tst-sscanf.c
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | NEWS | 6 | ||||
| -rw-r--r-- | stdio-common/tst-sscanf.c | 32 | ||||
| -rw-r--r-- | stdio-common/vfscanf.c | 12 |
4 files changed, 49 insertions, 9 deletions
diff --git a/ChangeLog b/ChangeLog index b15b0ab3fd..5b73423044 100644 --- a/ChangeLog +++ b/ChangeLog @@ -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. + 2013-05-21 Andreas Schwab <schwab@suse.de> [BZ #15014] diff --git a/NEWS b/NEWS index 7b466bfd90..b0c3072c45 100644 --- a/NEWS +++ b/NEWS @@ -9,9 +9,9 @@ Version 2.16.1 * The following bugs are resolved with this release: - 6530, 14195, 14547, 14459, 14476, 14562, 14621, 14648, 14699, 14719, 14756, - 14831, 15014, 15078, 15754, 15755, 16072, 16431, 16617, 17048, 17137, - 17187, 17325, 17625, 17630. + 6530, 14195, 14547, 14459, 14476, 14562, 14621, 14648, 14699, 14719, + 14756, 14831, 15014, 15078, 15754, 15755, 16072, 16431, 16617, 16618, + 17048, 17137, 17187, 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 a2db04cd99..9374c4865e 100644 --- a/stdio-common/tst-sscanf.c +++ b/stdio-common/tst-sscanf.c @@ -196,5 +196,37 @@ 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 23a8ac7694..f4fe6801ac 100644 --- a/stdio-common/vfscanf.c +++ b/stdio-common/vfscanf.c @@ -271,9 +271,10 @@ _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 = __builtin_expect ((wpmax <= SIZE_MAX / sizeof (CHAR_T) / 2), 1); \ + 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) \ @@ -285,14 +286,13 @@ _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); \ |