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Integer overflow when calculating AllocMem() size #84

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szsam opened this issue May 25, 2023 · 1 comment

szsam commented May 25, 2023

twin/server/resize.cpp

Lines 127 to 129 in b6e4e4b

    
           if (x > 0 && y > 0) { 
        
             if (!(saveNewCont = NewCont = (tcell *)AllocMem(x * y * sizeof(tcell)))) 
        
               return false;

This allocation size is derived from user input and the multiplication might overflow.
Consider adding upper bounds for x and y, e.g.

 if (x > 0 && y > 0 && x < 1000 && y < 1000) { 
   if (!(saveNewCont = NewCont = (tcell *)AllocMem(x * y * sizeof(tcell)))) 
     return false;

Owner

cosmos72 commented Jul 29, 2023

Thanks for spotting this!
Yes, that code shoud check for overflows before the multiplication.

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