64 lines
2.0 KiB
Diff
64 lines
2.0 KiB
Diff
From 282f691f5e57b6bf55ba51ad8c2be2cce8edb938 Mon Sep 17 00:00:00 2001
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From: Robin Watts <Robin.Watts@artifex.com>
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Date: Tue, 18 Jun 2024 18:22:55 +0100
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Subject: [PATCH] Bug 707788: Fix decode_utf8 to forbid overlong encodings.
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These can be used by malicious code to escape directories.
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CVE-2024-46954
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---
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base/gp_utf8.c | 13 ++++++++++++-
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1 file changed, 12 insertions(+), 1 deletion(-)
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diff --git a/base/gp_utf8.c b/base/gp_utf8.c
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index c33fc3550..b78977e37 100644
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--- a/base/gp_utf8.c
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+++ b/base/gp_utf8.c
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@@ -1,4 +1,4 @@
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-/* Copyright (C) 2001-2023 Artifex Software, Inc.
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+/* Copyright (C) 2001-2024 Artifex Software, Inc.
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All Rights Reserved.
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This software is provided AS-IS with no warranty, either express or
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@@ -25,12 +25,16 @@ decode_utf8(const char **inp, unsigned int i)
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if (i < 0x80) {
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} else if ((i & 0xE0) == 0xC0) {
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i &= 0x1F;
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+ if (i == 0)
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+ goto fail_overlong;
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c = (unsigned char)*in++;
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if ((c & 0xC0) != 0x80)
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goto fail;
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i = (i<<6) | (c & 0x3f);
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} else if ((i & 0xF0) == 0xE0) {
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i &= 0xF;
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+ if (i == 0)
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+ goto fail_overlong;
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c = (unsigned char)*in++;
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if ((c & 0xC0) != 0x80)
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goto fail;
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@@ -41,6 +45,8 @@ decode_utf8(const char **inp, unsigned int i)
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i = (i<<6) | (c & 0x3f);
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} else if ((i & 0xF8) == 0xF0) {
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i &= 0x7;
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+ if (i == 0)
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+ goto fail_overlong;
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c = (unsigned char)*in++;
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if ((c & 0xC0) != 0x80)
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goto fail;
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@@ -59,6 +65,11 @@ decode_utf8(const char **inp, unsigned int i)
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/* If we fail, unread the last one, and return the unicode replacement char. */
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fail:
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in--;
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+fail_overlong:
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+ /* If we jump to here it's because we've detected an 'overlong' encoding.
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+ * While this seems harmless, it's actually illegal, for good reason;
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+ * this is typically an attempt to sneak stuff past security checks, like
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+ * "../" in paths. Fail this. */
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i = 0xfffd;
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}
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*inp = in;
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--
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2.49.0
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