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| author | Marc Mutz <marc.mutz@kdab.com> | 2016-03-12 11:34:48 +0100 |
|---|---|---|
| committer | Marc Mutz <marc.mutz@kdab.com> | 2016-07-29 16:22:31 +0000 |
| commit | 8141d64527c5e7a1723e2caeeebb0cde4e591207 (patch) | |
| tree | 90a60295c45beb6a2083339c1ea94860b3c6a8de | |
| parent | f24cc53cc27d8ed4be4c1d0d2df059dd6a6909a9 (diff) | |
qgrayraster: fix UBs involving << with a negative LHS
Left-shifts of negative values are undefined in C++. In particular,
they don't behave arithmetically.
Reported by UBSan:
qgrayraster.c:510:19: runtime error: left shift of negative value -1/-42
qgrayraster.c:537:26: runtime error: left shift of negative value -1/-4/-128
qgrayraster.c:538:26: runtime error: left shift of negative value -1/-4/-128
qgrayraster.c:641:28: runtime error: left shift of negative value -1/-42
qgrayraster.c:676:44: runtime error: left shift of negative value -1/-4/-5/-14/-129
qgrayraster.c:807:19: runtime error: left shift of negative value -1/-42
qgrayraster.c:1101:9: runtime error: left shift of negative value -32/-46/-224/-8160
qgrayraster.c:1102:9: runtime error: left shift of negative value -32/-2626
qgrayraster.c:1454:36: runtime error: left shift of negative value -32/-96/-224/-466/-2626/-8160
qgrayraster.c:1535:30: runtime error: left shift of negative value -32/-46/-224/-2626/-8160
Fix by using ordinary multiplication instead, because negative
left-hand-side values don't look like they are an error.
Change-Id: I2e96de51adb4a030de8a49869ddd98a31dab31b3
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
| -rw-r--r-- | src/gui/painting/qgrayraster.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/gui/painting/qgrayraster.c b/src/gui/painting/qgrayraster.c index b536028fe3..5ce1895541 100644 --- a/src/gui/painting/qgrayraster.c +++ b/src/gui/painting/qgrayraster.c @@ -202,13 +202,13 @@ #define ONE_PIXEL ( 1L << PIXEL_BITS ) #define PIXEL_MASK ( -1L << PIXEL_BITS ) #define TRUNC( x ) ( (TCoord)( (x) >> PIXEL_BITS ) ) -#define SUBPIXELS( x ) ( (TPos)(x) << PIXEL_BITS ) +#define SUBPIXELS( x ) ( (TPos)(x) * ( 1 << PIXEL_BITS ) ) #define FLOOR( x ) ( (x) & -ONE_PIXEL ) #define CEILING( x ) ( ( (x) + ONE_PIXEL - 1 ) & -ONE_PIXEL ) #define ROUND( x ) ( ( (x) + ONE_PIXEL / 2 ) & -ONE_PIXEL ) #if PIXEL_BITS >= 6 -#define UPSCALE( x ) ( (x) << ( PIXEL_BITS - 6 ) ) +#define UPSCALE( x ) ( (x) * ( 1 << ( PIXEL_BITS - 6 ) ) ) #define DOWNSCALE( x ) ( (x) >> ( PIXEL_BITS - 6 ) ) #else #define UPSCALE( x ) ( (x) >> ( 6 - PIXEL_BITS ) ) |