Guard against empty containers in ARRL Digi decode path (Qt6 crash) - #51
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Guard against empty containers in ARRL Digi decode path (Qt6 crash)#51cjkjellander wants to merge 1 commit into
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The ARRL Digital contest feature indexes several containers with the
unchecked operator[] while processing decodes in readFromStdout(),
which segfaults under Qt6 (Qt5's QByteRef/QList tolerated it):
- activeWorked(): m_activeCall[call].bands is empty when the callsign
was never seeded via ARRL_Digi_Update(), so ba[3]='d' (and the other
band slots) write past the end of the QByteArray.
- ARRL_Digi_Update(): dt.messageWords()[0] indexes an empty QStringList
for a decode that yields no words.
- readFromStdout(): word[0] indexes the result of
split(" ", SkipEmptyParts), which can be empty.
Add isEmpty()/size() guards at each site. These paths only execute in
ARRL_DIGI special-operating mode, which is why they went unnoticed.
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The ARRL Digital contest feature (
SpecOp::ARRL_DIGI) indexes severalcontainers with the unchecked
operator[]while processing decodes inMainWindow::readFromStdout(). When a decode yields an empty result thesebecome out-of-bounds accesses. Under Qt6 (unlike Qt5's tolerant
QByteRef/QList) they dereference invalid memory and segfault.Three sites, all reached only in ARRL_DIGI mode (hence rarely hit):
MainWindow::activeWorked()—m_activeCall[call].bandsis empty whenthe callsign was never seeded (a default-constructed map entry), so
ba[0..6]=...writes past the end of theQByteArray.MainWindow::ARRL_Digi_Update()—dt.messageWords()[0]indexes anempty
QStringListfor a decode with no words, then.left(3)reads garbage.MainWindow::readFromStdout()—word[0]indexes the result ofsplit(" ", SkipEmptyParts), which can be empty.Each site gets an
isEmpty()/size()guard; behavior is unchanged when thecontainers are populated.
Found via gdb backtraces on a Qt6
RelWithDebInfobuild while decoding FT8 inARRL_DIGI mode — the crash reproduces reliably once
jt9produces decodes.