89 lines
3.0 KiB
Diff
89 lines
3.0 KiB
Diff
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Fix CVE-2015-1472 - heap buffer overflow in wscanf
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Backport from upstream:
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https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06
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See: https://bugzilla.redhat.com/show_bug.cgi?id=1188235
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Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
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diff --git a/stdio-common/tst-sscanf.c b/stdio-common/tst-sscanf.c
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index aece3f2..8a2eb9e 100644
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--- a/stdio-common/tst-sscanf.c
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+++ b/stdio-common/tst-sscanf.c
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@@ -233,5 +233,38 @@ main (void)
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}
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}
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+ /* BZ #16618
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+ The test will segfault during SSCANF if the buffer overflow
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+ is not fixed. The size of `s` is such that it forces the use
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+ of malloc internally and this triggers the incorrect computation.
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+ Thus the value for SIZE is arbitrariy high enough that malloc
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+ is used. */
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+ {
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+#define SIZE 131072
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+ CHAR *s = malloc ((SIZE + 1) * sizeof (*s));
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+ if (s == NULL)
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+ abort ();
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+ for (size_t i = 0; i < SIZE; i++)
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+ s[i] = L('0');
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+ s[SIZE] = L('\0');
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+ int i = 42;
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+ /* Scan multi-digit zero into `i`. */
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+ if (SSCANF (s, L("%d"), &i) != 1)
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+ {
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+ printf ("FAIL: bug16618: SSCANF did not read one input item.\n");
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+ result = 1;
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+ }
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+ if (i != 0)
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+ {
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+ printf ("FAIL: bug16618: Value of `i` was not zero as expected.\n");
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+ result = 1;
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+ }
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+ free (s);
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+ if (result != 1)
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+ printf ("PASS: bug16618: Did not crash.\n");
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+#undef SIZE
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+ }
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+
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+
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return result;
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}
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diff --git a/stdio-common/vfscanf.c b/stdio-common/vfscanf.c
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index cd129a8..0e204e7 100644
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--- a/stdio-common/vfscanf.c
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+++ b/stdio-common/vfscanf.c
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@@ -272,9 +272,10 @@ _IO_vfscanf_internal (_IO_FILE *s, const char *format, _IO_va_list argptr,
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if (__glibc_unlikely (wpsize == wpmax)) \
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{ \
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CHAR_T *old = wp; \
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- size_t newsize = (UCHAR_MAX + 1 > 2 * wpmax \
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- ? UCHAR_MAX + 1 : 2 * wpmax); \
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- if (use_malloc || !__libc_use_alloca (newsize)) \
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+ bool fits = __glibc_likely (wpmax <= SIZE_MAX / sizeof (CHAR_T) / 2); \
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+ size_t wpneed = MAX (UCHAR_MAX + 1, 2 * wpmax); \
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+ size_t newsize = fits ? wpneed * sizeof (CHAR_T) : SIZE_MAX; \
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+ if (!__libc_use_alloca (newsize)) \
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{ \
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wp = realloc (use_malloc ? wp : NULL, newsize); \
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if (wp == NULL) \
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@@ -286,14 +287,13 @@ _IO_vfscanf_internal (_IO_FILE *s, const char *format, _IO_va_list argptr,
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} \
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if (! use_malloc) \
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MEMCPY (wp, old, wpsize); \
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- wpmax = newsize; \
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+ wpmax = wpneed; \
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use_malloc = true; \
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} \
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else \
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{ \
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size_t s = wpmax * sizeof (CHAR_T); \
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- wp = (CHAR_T *) extend_alloca (wp, s, \
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- newsize * sizeof (CHAR_T)); \
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+ wp = (CHAR_T *) extend_alloca (wp, s, newsize); \
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wpmax = s / sizeof (CHAR_T); \
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if (old != NULL) \
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MEMCPY (wp, old, wpsize); \
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--
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1.9.4
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