From 591d1fd28a42adc04a38d5b5b515d3bfa14e3ae2 Mon Sep 17 00:00:00 2001
From: Albert Astals Cid <albert.astals.cid@kdab.com>
Date: Tue, 4 Sep 2018 14:19:52 +0200
Subject: [PATCH] ppmhandler: Fix undefined overflow behavior

image/qppmhandler.cpp:260:53: runtime error: signed integer overflow: 44444444 * 255 cannot be represented in type 'int'
    #0 0x4cbc8a in read_pbm_body(QIODevice*, char, int, int, int, QImage*) /src/qt/qtbase/src/gui/image/qppmhandler.cpp:260:53
    #1 0x4ca3d8 in QPpmHandler::read(QImage*) /src/qt/qtbase/src/gui/image/qppmhandler.cpp:514:10
    #2 0x4b238d in QImageReader::read(QImage*) /src/qt/qtbase/src/gui/image/qimagereader.cpp:1253:22
    #3 0x4b1b61 in QImageReader::read() /src/qt/qtbase/src/gui/image/qimagereader.cpp:1201:12
    #4 0x486f66 in QImage::fromData(unsigned char const*, int, char const*) /src/qt/qtbase/src/gui/image/qimage.cpp:3624:37
    #5 0x486cd8 in QImage::loadFromData(unsigned char const*, int, char const*) /src/qt/qtbase/src/gui/image/qimage.cpp:3590:13
    #6 0x434b2e in LLVMFuzzerTestOneInput /src/qimage_fuzzer.cc:28:7
    #7 0x44b167 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/libfuzzer/FuzzerLoop.cpp:570:15
    #8 0x44a535 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:479:3
    #9 0x44c428 in fuzzer::Fuzzer::MutateAndTestOne() /src/libfuzzer/FuzzerLoop.cpp:707:19
    #10 0x44d1b5 in fuzzer::Fuzzer::Loop(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, fuzzer::fuzzer_allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&) /src/libfuzzer/FuzzerLoop.cpp:838:5
    #11 0x440a29 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:764:6
    #12 0x434bf8 in main /src/libfuzzer/FuzzerMain.cpp:20:10
    #13 0x7fe01697282f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #14 0x409bb8 in _start (/out/qimage_fuzzer+0x409bb8)

Change-Id: Ibc5df6db52639f12319910b927f6443d927206d8
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
---
 src/gui/image/qppmhandler.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gui/image/qppmhandler.cpp b/src/gui/image/qppmhandler.cpp
index 6f6469042b..bfde0aa76e 100644
--- a/src/gui/image/qppmhandler.cpp
+++ b/src/gui/image/qppmhandler.cpp
@@ -258,7 +258,7 @@ static bool read_pbm_body(QIODevice *device, char type, int w, int h, int mcc, Q
                     }
                 } else {
                     while (n--) {
-                        *p++ = read_pbm_int(device) * 255 / mcc;
+                        *p++ = (read_pbm_int(device) & 0xffff) * 255 / mcc;
                     }
                 }
             } else {                                // 32 bits