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[partition] Avoid crash when PARTITION_UNSAFE is on

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PARTITION_UNSAFE is a debug mode. It is not used in
production, because it allows you to pick an install
device that would be dangerous (e.g. the current / device).

Existing code kept two copies of a list of pointers,
and deleted pointers from one of the lists and returned
the other -- which now contains dangling pointers.

Refactor by applying suitable lambdas to a single
copy of the list; this avoids copying the list so
there is no danger of dangling pointers.
This commit is contained in:
Adriaan de Groot 2021-06-08 13:22:56 +02:00
parent a57a1fdbd8
commit eb627bc055
1 changed files with 22 additions and 11 deletions
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33
src/modules/partition/core/DeviceList.cpp
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@ -125,12 +125,27 @@ getDevices( DeviceType which )
DeviceList devices = backend->scanDevices( /* excludeReadOnly */ true );
#endif
/* The list of devices is cleaned up for use:
* - some devices can **never** be used (e.g. floppies, nullptr)
* - some devices can be used if unsafe mode is on, but not in normal operation
* Two lambda's are defined,
* - removeInAllModes()
* - removeInSafeMode()
* To handle the difference.
*/
#ifdef DEBUG_PARTITION_UNSAFE
cWarning() << "Allowing unsafe partitioning choices." << devices.count() << "candidates.";
DeviceList unsafeDevices = devices;
#ifdef DEBUG_PARTITION_LAME
cDebug() << Logger::SubEntry << "it has been lamed, and will fail.";
cDebug() << Logger::SubEntry << "unsafe partitioning has been lamed, and will fail.";
#endif
// Unsafe partitioning
auto removeInAllModes = []( DeviceList& l, DeviceList::iterator& it) { return erase(l, it); };
auto removeInSafeMode = []( DeviceList&, DeviceList::iterator& it) { return ++it; };
#else
// Safe partitioning
auto removeInAllModes = []( DeviceList& l, DeviceList::iterator& it) { return erase(l, it); };
auto& removeInSafeMode = removeFromAll;
#endif
cDebug() << "Removing unsuitable devices:" << devices.count() << "candidates.";
@ -142,27 +157,27 @@ getDevices( DeviceType which )
if ( !( *it ) )
{
cDebug() << Logger::SubEntry << "Skipping nullptr device";
it = erase( devices, it );
it = removeInAllModes( devices, it );
}
else if ( isZRam( *it ) )
{
cDebug() << Logger::SubEntry << "Removing zram" << it;
it = erase( devices, it );
it = removeInAllModes( devices, it );
}
else if ( isFloppyDrive( ( *it ) ) )
{
cDebug() << Logger::SubEntry << "Removing floppy disk" << it;
it = erase( devices, it );
it = removeInAllModes( devices, it );
}
else if ( writableOnly && hasRootPartition( *it ) )
{
cDebug() << Logger::SubEntry << "Removing device with root filesystem (/) on it" << it;
it = erase( devices, it );
it = removeInSafeMode( devices, it );
}
else if ( writableOnly && isIso9660( *it ) )
{
cDebug() << Logger::SubEntry << "Removing device with iso9660 filesystem (probably a CD) on it" << it;
it = erase( devices, it );
it = removeInSafeMode( devices, it );
}
else
{
@ -170,11 +185,7 @@ getDevices( DeviceType which )
}
}
cDebug() << Logger::SubEntry << "there are" << devices.count() << "devices left.";
#ifdef DEBUG_PARTITION_UNSAFE
return unsafeDevices;
#else
return devices;
#endif
}
} // namespace PartUtils