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From a3a1f4163c4d0f9a36056c8640661a88674ae8a2 Mon Sep 17 00:00:00 2001 |
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From: Jeff Law <law@redhat.com> |
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Date: Mon, 15 Dec 2014 10:09:07 +0100 |
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Subject: [PATCH] CVE-2012-3406: Stack overflow in vfprintf [BZ #16617] |
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|
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A larger number of format specifiers coudld cause a stack overflow, |
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potentially allowing to bypass _FORTIFY_SOURCE format string |
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protection. |
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|
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(cherry picked from commit a5357b7ce2a2982c5778435704bcdb55ce3667a0) |
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(cherry picked from commit ae61fc7b33d9d99d2763c16de8275227dc9748ba) |
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|
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Conflicts: |
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NEWS |
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--- |
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ChangeLog | 9 +++++++ |
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NEWS | 4 ++- |
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stdio-common/Makefile | 2 +- |
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stdio-common/bug23-2.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++ |
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stdio-common/bug23-3.c | 50 +++++++++++++++++++++++++++++++++++ |
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stdio-common/bug23-4.c | 31 ++++++++++++++++++++++ |
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stdio-common/vfprintf.c | 40 ++++++++++++++++++++++++++-- |
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7 files changed, 202 insertions(+), 4 deletions(-) |
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create mode 100644 stdio-common/bug23-2.c |
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create mode 100644 stdio-common/bug23-3.c |
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create mode 100644 stdio-common/bug23-4.c |
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|
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#diff --git a/ChangeLog b/ChangeLog |
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#index ac7d980..88d2f1e 100644 |
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#--- a/ChangeLog |
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#+++ b/ChangeLog |
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#@@ -1,3 +1,12 @@ |
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#+2014-12-15 Jeff Law <law@redhat.com> |
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#+ |
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#+ [BZ #16617] |
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#+ * stdio-common/vfprintf.c (vfprintf): Allocate large specs array |
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#+ on the heap. (CVE-2012-3406) |
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#+ * stdio-common/bug23-2.c, stdio-common/bug23-3.c: New file. |
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#+ * stdio-common/bug23-4.c: New file. Test case by Joseph Myers. |
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#+ * stdio-common/Makefile (tests): Add bug23-2, bug23-3, bug23-4. |
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#+ |
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# 2014-11-24 Siddhesh Poyarekar <siddhesh@redhat.com> |
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# |
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# [BZ #17266] |
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#diff --git a/NEWS b/NEWS |
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#index 3de92cd..f6cdb66 100644 |
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#--- a/NEWS |
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#+++ b/NEWS |
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#@@ -9,7 +9,7 @@ Version 2.20.1 |
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# |
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# * The following bugs are resolved with this release: |
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# |
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#- 17266, 17370, 17371, 17460, 17485, 17555, 17625. |
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#+ 16617, 17266, 17370, 17371, 17460, 17485, 17555, 17625. |
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# |
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# * CVE-2104-7817 The wordexp function could ignore the WRDE_NOCMD flag |
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# under certain input conditions resulting in the execution of a shell for |
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#@@ -17,6 +17,8 @@ Version 2.20.1 |
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# implementation now checks WRDE_NOCMD immediately before executing the |
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# shell and returns the error WRDE_CMDSUB as expected. |
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# |
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#+* CVE-2012-3406 printf-style functions could run into a stack overflow when |
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#+ processing format strings with a large number of format specifiers.a |
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# |
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# Version 2.20 |
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# |
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diff --git a/stdio-common/Makefile b/stdio-common/Makefile |
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index 5f8e534..e5e45b6 100644 |
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--- a/stdio-common/Makefile |
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+++ b/stdio-common/Makefile |
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@@ -57,7 +57,7 @@ tests := tstscanf test_rdwr test-popen tstgetln test-fseek \ |
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bug19 bug19a tst-popen2 scanf13 scanf14 scanf15 bug20 bug21 bug22 \ |
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scanf16 scanf17 tst-setvbuf1 tst-grouping bug23 bug24 \ |
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bug-vfprintf-nargs tst-long-dbl-fphex tst-fphex-wide tst-sprintf3 \ |
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- bug25 tst-printf-round bug26 |
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+ bug25 tst-printf-round bug23-2 bug23-3 bug23-4 bug26 |
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|
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test-srcs = tst-unbputc tst-printf |
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|
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diff --git a/stdio-common/bug23-2.c b/stdio-common/bug23-2.c |
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new file mode 100644 |
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index 0000000..9e0cfe6 |
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--- /dev/null |
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+++ b/stdio-common/bug23-2.c |
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@@ -0,0 +1,70 @@ |
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+#include <stdio.h> |
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+#include <string.h> |
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+#include <stdlib.h> |
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+ |
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+static const char expected[] = "\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55\ |
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+\n\ |
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+a\n\ |
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+abbcd55%%%%%%%%%%%%%%%%%%%%%%%%%%\n"; |
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+ |
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+static int |
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+do_test (void) |
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+{ |
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+ char *buf = malloc (strlen (expected) + 1); |
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+ snprintf (buf, strlen (expected) + 1, |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n", |
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+ "a", "b", "c", "d", 5); |
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+ return strcmp (buf, expected) != 0; |
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+} |
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+ |
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+#define TEST_FUNCTION do_test () |
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+#include "../test-skeleton.c" |
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diff --git a/stdio-common/bug23-3.c b/stdio-common/bug23-3.c |
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new file mode 100644 |
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index 0000000..57c8cef |
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--- /dev/null |
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+++ b/stdio-common/bug23-3.c |
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@@ -0,0 +1,50 @@ |
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+#include <stdio.h> |
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+#include <string.h> |
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+#include <stdlib.h> |
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+ |
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+int |
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+do_test (void) |
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+{ |
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+ size_t instances = 16384; |
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+#define X0 "\n%1$s\n" "%1$s" "%2$s" "%2$s" "%3$s" "%4$s" "%5$d" "%5$d" |
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+ const char *item = "\na\nabbcd55"; |
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+#define X3 X0 X0 X0 X0 X0 X0 X0 X0 |
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+#define X6 X3 X3 X3 X3 X3 X3 X3 X3 |
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+#define X9 X6 X6 X6 X6 X6 X6 X6 X6 |
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+#define X12 X9 X9 X9 X9 X9 X9 X9 X9 |
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+#define X14 X12 X12 X12 X12 |
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+#define TRAILER "%%%%%%%%%%%%%%%%%%%%%%%%%%" |
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+#define TRAILER2 TRAILER TRAILER |
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+ size_t length = instances * strlen (item) + strlen (TRAILER) + 1; |
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+ |
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+ char *buf = malloc (length + 1); |
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+ snprintf (buf, length + 1, |
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+ X14 TRAILER2 "\n", |
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+ "a", "b", "c", "d", 5); |
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+ |
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+ const char *p = buf; |
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+ size_t i; |
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+ for (i = 0; i < instances; ++i) |
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+ { |
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+ const char *expected; |
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+ for (expected = item; *expected; ++expected) |
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+ { |
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+ if (*p != *expected) |
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+ { |
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+ printf ("mismatch at offset %zu (%zu): expected %d, got %d\n", |
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+ (size_t) (p - buf), i, *expected & 0xFF, *p & 0xFF); |
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+ return 1; |
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+ } |
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+ ++p; |
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+ } |
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+ } |
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+ if (strcmp (p, TRAILER "\n") != 0) |
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+ { |
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+ printf ("mismatch at trailer: [%s]\n", p); |
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+ return 1; |
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+ } |
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+ free (buf); |
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+ return 0; |
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+} |
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+#define TEST_FUNCTION do_test () |
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+#include "../test-skeleton.c" |
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diff --git a/stdio-common/bug23-4.c b/stdio-common/bug23-4.c |
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new file mode 100644 |
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index 0000000..a478564 |
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--- /dev/null |
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+++ b/stdio-common/bug23-4.c |
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@@ -0,0 +1,31 @@ |
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+#include <stdio.h> |
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+#include <stdlib.h> |
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+#include <string.h> |
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+#include <sys/resource.h> |
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+ |
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+#define LIMIT 1000000 |
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+ |
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+int |
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+main (void) |
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+{ |
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+ struct rlimit lim; |
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+ getrlimit (RLIMIT_STACK, &lim); |
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+ lim.rlim_cur = 1048576; |
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+ setrlimit (RLIMIT_STACK, &lim); |
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+ char *fmtstr = malloc (4 * LIMIT + 1); |
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+ if (fmtstr == NULL) |
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+ abort (); |
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+ char *output = malloc (LIMIT + 1); |
| 236 |
+ if (output == NULL) |
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+ abort (); |
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+ for (size_t i = 0; i < LIMIT; i++) |
| 239 |
+ memcpy (fmtstr + 4 * i, "%1$d", 4); |
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+ fmtstr[4 * LIMIT] = '\0'; |
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+ int ret = snprintf (output, LIMIT + 1, fmtstr, 0); |
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+ if (ret != LIMIT) |
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+ abort (); |
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+ for (size_t i = 0; i < LIMIT; i++) |
| 245 |
+ if (output[i] != '0') |
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+ abort (); |
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+ return 0; |
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+} |
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diff --git a/stdio-common/vfprintf.c b/stdio-common/vfprintf.c |
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index c4ff833..429a3d1 100644 |
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--- a/stdio-common/vfprintf.c |
| 252 |
+++ b/stdio-common/vfprintf.c |
| 253 |
@@ -263,6 +263,12 @@ vfprintf (FILE *s, const CHAR_T *format, va_list ap) |
| 254 |
/* For the argument descriptions, which may be allocated on the heap. */ |
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void *args_malloced = NULL; |
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|
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+ /* For positional argument handling. */ |
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+ struct printf_spec *specs; |
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+ |
| 260 |
+ /* Track if we malloced the SPECS array and thus must free it. */ |
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+ bool specs_malloced = false; |
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+ |
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/* This table maps a character into a number representing a |
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class. In each step there is a destination label for each |
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class. */ |
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@@ -1679,8 +1685,8 @@ do_positional: |
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size_t nspecs = 0; |
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/* A more or less arbitrary start value. */ |
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size_t nspecs_size = 32 * sizeof (struct printf_spec); |
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- struct printf_spec *specs = alloca (nspecs_size); |
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|
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+ specs = alloca (nspecs_size); |
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/* The number of arguments the format string requests. This will |
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determine the size of the array needed to store the argument |
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attributes. */ |
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@@ -1721,11 +1727,39 @@ do_positional: |
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if (nspecs * sizeof (*specs) >= nspecs_size) |
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{ |
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/* Extend the array of format specifiers. */ |
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+ if (nspecs_size * 2 < nspecs_size) |
| 281 |
+ { |
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+ __set_errno (ENOMEM); |
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+ done = -1; |
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+ goto all_done; |
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+ } |
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struct printf_spec *old = specs; |
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- specs = extend_alloca (specs, nspecs_size, 2 * nspecs_size); |
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+ if (__libc_use_alloca (2 * nspecs_size)) |
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+ specs = extend_alloca (specs, nspecs_size, 2 * nspecs_size); |
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+ else |
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+ { |
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+ nspecs_size *= 2; |
| 293 |
+ specs = malloc (nspecs_size); |
| 294 |
+ if (specs == NULL) |
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+ { |
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+ __set_errno (ENOMEM); |
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+ specs = old; |
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+ done = -1; |
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+ goto all_done; |
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+ } |
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+ } |
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|
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/* Copy the old array's elements to the new space. */ |
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memmove (specs, old, nspecs * sizeof (*specs)); |
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+ |
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+ /* If we had previously malloc'd space for SPECS, then |
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+ release it after the copy is complete. */ |
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+ if (specs_malloced) |
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+ free (old); |
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+ |
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+ /* Now set SPECS_MALLOCED if needed. */ |
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+ if (!__libc_use_alloca (nspecs_size)) |
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+ specs_malloced = true; |
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} |
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|
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/* Parse the format specifier. */ |
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@@ -2046,6 +2080,8 @@ do_positional: |
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} |
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|
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all_done: |
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+ if (specs_malloced) |
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+ free (specs); |
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if (__glibc_unlikely (args_malloced != NULL)) |
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free (args_malloced); |
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if (__glibc_unlikely (workstart != NULL)) |
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-- |
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1.8.4.5 |
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