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Don't allow too many nested macro expansions. Until now, it was possible to

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send the assembler in an endless loop by a recursive macro without end
condition or a set of macros that called each other.


git-svn-id: svn://svn.cc65.org/cc65/trunk@5038 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2011-06-07 21:17:35 +00:00
parent f8089b98c1
commit 5db7604eff
1 changed files with 23 additions and 1 deletions
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24
src/ca65/macro.c
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@ -107,6 +107,7 @@ struct Macro {
TokNode* TokRoot; /* Root of token list */
TokNode* TokLast; /* Pointer to last token in list */
unsigned char Style; /* Macro style */
unsigned char Incomplete; /* Macro is currently built */
StrBuf Name; /* Macro name, dynamically allocated */
};
@ -139,6 +140,9 @@ struct MacExp {
unsigned LISlot; /* Slot for additional line infos */
};
/* Maximum number of nested macro expansions */
#define MAX_MACEXPANSIONS 256U
/* Number of active macro expansions */
static unsigned MacExpansions = 0;
@ -230,6 +234,7 @@ static Macro* NewMacro (const StrBuf* Name, unsigned char Style)
M->TokRoot = 0;
M->TokLast = 0;
M->Style = Style;
M->Incomplete = 1;
SB_Init (&M->Name);
SB_Copy (&M->Name, Name);
@ -533,6 +538,9 @@ void MacDef (unsigned Style)
NextTok ();
}
/* Reset the Incomplete flag now that parsing is done */
M->Incomplete = 0;
Done:
/* Switch out of raw token mode */
LeaveRawTokenMode ();
@ -677,7 +685,7 @@ static void StartExpClassic (Macro* M)
token_t Term;
/* Create a structure holding expansion data. This must be done before
/* Create a structure holding expansion data. This must be done before
* skipping the macro name, because the call to NextTok may cause a new
* expansion if the next token is actually a .define style macro.
*/
@ -854,6 +862,20 @@ void MacExpandStart (void)
Macro* M = HT_FindEntry (&MacroTab, &CurTok.SVal);
CHECK (M != 0);
/* We cannot expand an incomplete macro */
if (M->Incomplete) {
Error ("Cannot expand an incomplete macro");
return;
}
/* Don't allow too many nested macro expansions - otherwise it is possible
* to force an endless loop and assembler crash.
*/
if (MacExpansions >= MAX_MACEXPANSIONS) {
Error ("Too many nested macro expansions");
return;
}
/* Call the apropriate subroutine */
switch (M->Style) {
case MAC_STYLE_CLASSIC: StartExpClassic (M); break;