1berry/pawn-compiler
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

replaces dangling pointers in initarray with indexes

Browse Source 
In `initarray`, `prev1` and `prev2` are dangling pointers. When assigned, they point to an address of an item in the literal queue. The compiler checks the literal queue size before adding an element. If the size isn't sufficient to hold another element, it reallocates the literal queue to accommodate more items. When the reallocation happens, the previous references (`prev1` and `prev2`) to the elements of the literal queue are invalidated. De-referencing the broken pointers will cause undefined behavior.

This commit replaces the pointers with indexes. The indexes are invariant to the reallocation.
This commit is contained in:
Yashas 2017-12-31 18:30:06 +05:30 committed by GitHub
parent 7ea961990c
commit 19a8bfd1f3
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
source/compiler/sc1.c
View File

@ -2589,7 +2589,7 @@ static cell initarray(int ident,int tag,int dim[],int numdim,int cur,
int idx,idx_ellips,vidx,do_insert;
int abortparse;
int curlit;
cell *prev1=NULL,*prev2=NULL;
int prev1_idx=-1,prev2_idx=-1;
assert(cur>=0 && cur<numdim);
assert(startlit>=0);
@ -2627,13 +2627,13 @@ static cell initarray(int ident,int tag,int dim[],int numdim,int cur,
/* found an ellipsis; fill up the rest of the array with a series
* of one-dimensional arrays ("2d ellipsis")
*/
if (prev1!=NULL) {
if (prev1_idx!=-1) {
for (idx_ellips=1; idx < dim[cur]; idx++, idx_ellips++) {
for (vidx=0; vidx < dsize; vidx++) {
if (prev2!=NULL)
litadd(prev1[vidx]+idx_ellips*(prev1[vidx]-prev2[vidx]));
if (prev2_idx!=-1)
litadd(litq[prev1_idx+vidx]+idx_ellips*(litq[prev1_idx+vidx]-litq[prev2_idx+vidx]));
else
litadd(prev1[vidx]);
litadd(litq[prev1_idx+vidx]);
} /* for */
append_constval(lastdim,itoh(idx),dsize,0);
} /* for */
@ -2641,8 +2641,8 @@ static cell initarray(int ident,int tag,int dim[],int numdim,int cur,
} else
error(41); /* invalid ellipsis, array size unknown */
} else {
prev2=prev1;
prev1=&litq[litidx];
prev2_idx=prev1_idx;
prev1_idx=litidx;
dsize=initvector(ident,tag,dim[cur+1],curlit,TRUE,enumroot,errorfound);
/* The final dimension may be variable length. We need to save the
* lengths of the final dimensions in order to set the indirection