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43 lines
1.8 KiB
43 lines
1.8 KiB
From 661f6bfd032dacc62841037732816a583640e187 Mon Sep 17 00:00:00 2001
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From: "Richard J. Moore" <rich@kde.org>
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Date: Sat, 21 Feb 2015 17:43:21 +0000
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Subject: [PATCH] Fix a division by zero when processing malformed BMP files.
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This fixes a division by 0 when processing a maliciously crafted BMP
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file. No impact beyond DoS.
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Task-number: QTBUG-44547
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Change-Id: Ifcded2c0aa712e90d23e6b3969af0ec3add53973
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Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
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Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
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---
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src/gui/image/qbmphandler.cpp | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/src/gui/image/qbmphandler.cpp b/src/gui/image/qbmphandler.cpp
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index 21c1a2f..df66499 100644
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--- a/src/gui/image/qbmphandler.cpp
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+++ b/src/gui/image/qbmphandler.cpp
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@@ -314,12 +314,20 @@ static bool read_dib_body(QDataStream &s, const BMP_INFOHDR &bi, int offset, int
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}
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} else if (comp == BMP_BITFIELDS && (nbits == 16 || nbits == 32)) {
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red_shift = calc_shift(red_mask);
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+ if (((red_mask >> red_shift) + 1) == 0)
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+ return false;
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red_scale = 256 / ((red_mask >> red_shift) + 1);
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green_shift = calc_shift(green_mask);
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+ if (((green_mask >> green_shift) + 1) == 0)
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+ return false;
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green_scale = 256 / ((green_mask >> green_shift) + 1);
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blue_shift = calc_shift(blue_mask);
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+ if (((blue_mask >> blue_shift) + 1) == 0)
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+ return false;
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blue_scale = 256 / ((blue_mask >> blue_shift) + 1);
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alpha_shift = calc_shift(alpha_mask);
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+ if (((alpha_mask >> alpha_shift) + 1) == 0)
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+ return false;
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alpha_scale = 256 / ((alpha_mask >> alpha_shift) + 1);
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} else if (comp == BMP_RGB && (nbits == 24 || nbits == 32)) {
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blue_mask = 0x000000ff;
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--
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2.0.5
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