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Fix use-after-free when ending a transaction with registered users #7

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Fix use-after-free when ending a transaction with registered users #7

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12 changes: 11 additions & 1 deletion client/FBTransaction.pas
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Original file line number Diff line number Diff line change
Expand Up @@ -330,7 +330,17 @@ procedure TFBTransaction.DoDefaultTransactionEnd(Force: boolean);
var i: integer;
intf: IUnknown;
user: ITransactionUser;
begin
SelfRef: ITransaction;
begin
{A transaction user's TransactionEnding may release the last interface
reference to this transaction, which would free it while this method is
still running and leave the Commit/Rollback below operating on a destroyed
object. TFB30TimeZoneServices does exactly that: it starts an internal
transaction for the time zone lookups, registers itself on it, and clears
its own reference in TransactionEnding. Nothing else holds one - the
interface list stores raw object pointers, not counted references - so the
object went away mid-call. Hold a reference for the duration.}
SelfRef := self;
if InTransaction and not FForeignHandle then
begin
for i := 0 to InterfaceCount - 1 do
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