diff options
| author | Marc Mutz <marc.mutz@kdab.com> | 2015-01-19 01:26:56 +0100 |
|---|---|---|
| committer | Marc Mutz <marc.mutz@kdab.com> | 2015-01-19 10:43:45 +0100 |
| commit | b69c2e86de99cb2ac9bcd2e33ae77c960cfbc57a (patch) | |
| tree | 7f7a3381b66607a8a95817f093ea516a1ab652fc /src/corelib/tools | |
| parent | 62a96dbb53d77d6cd7320c6fc8d33ee9c4add0fe (diff) | |
QFreeList: fix undefined behavior
Signed integer overflow is undefined behavior ([expr]/4),
but unsigned arithmetic doesn't overflow, so isn't
([basic.fundamental]/4, footnote there).
So, use unsigned arithmetic for the loop-around serial
number generation in incrementserial(). While we're at
it, also use it for the masking operation in the same
function.
Found by UBSan.
Change-Id: I500fae9d80fd3f6e39d06e79a53d271b82ea8df8
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Diffstat (limited to 'src/corelib/tools')
| -rw-r--r-- | src/corelib/tools/qfreelist_p.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/corelib/tools/qfreelist_p.h b/src/corelib/tools/qfreelist_p.h index bfb03fb723..189140016c 100644 --- a/src/corelib/tools/qfreelist_p.h +++ b/src/corelib/tools/qfreelist_p.h @@ -171,7 +171,7 @@ class QFreeList // take the current serial number from \a o, increment it, and store it in \a n static inline int incrementserial(int o, int n) { - return (n & ConstantsType::IndexMask) | ((o + ConstantsType::SerialCounter) & ConstantsType::SerialMask); + return int((uint(n) & ConstantsType::IndexMask) | ((uint(o) + ConstantsType::SerialCounter) & ConstantsType::SerialMask)); } // the blocks |