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calc engine: fix four out-of-bounds accesses in the sCalc/aCalc perform paths #41

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calc engine: fix four out-of-bounds accesses in the sCalc/aCalc perform paths #41

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15108f2
sCalc: clamp the shift count against a negative operand
physwkim Jul 19, 2026
bdac23f
sCalc: bound the LITERAL_STRING copy by incrementing its counter
physwkim Jul 19, 2026
4ad3444
aCalc: cap the SUBRANGE upper bound at arraySize-1
physwkim Jul 19, 2026
01e0ea5
calcUtil: reject an nderiv fit window larger than the array
physwkim Jul 19, 2026
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2 changes: 1 addition & 1 deletion calcApp/src/aCalcPerform.c
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Expand Up @@ -1531,7 +1531,7 @@ long aCalcPerform(double *p_dArg, int num_dArgs, double **pp_aArg,
j = (int)ps2->d;
if (j < 0) j += arraySize;
i = myMAX(myMIN(i,arraySize),0);
j = myMIN(j,arraySize);
j = myMIN(j,arraySize-1);
if (aCalcPerformDebug > 20) printf("\tSUBRANGE*: ix1=%d, ix2=%d\n", i, j);
if (op == SUBRANGE) {
ps->firstEl = 0;
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1 change: 1 addition & 0 deletions calcApp/src/calcUtil.c
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Expand Up @@ -30,6 +30,7 @@ int nderiv(double *x, double *y, int n, double *d, int npts, double *lx)
double c, b, a;

m = 2*npts+1;
if (n < m) return(-1); /* fit window larger than the array: refuse rather than read OOB */
/* first m/2+1 points */
e = fitpoly(x,y,m, &c, &b, &a, NULL);
if (e) {
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4 changes: 2 additions & 2 deletions calcApp/src/sCalcPerform.c
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Expand Up @@ -1265,7 +1265,7 @@ epicsShareFunc long
ps1 = ps;
toDouble(ps1);
j = myNINT(ps1->d);
j = myMIN(j,SCALC_STRING_SIZE);
j = myMAX(myMIN(j,SCALC_STRING_SIZE),0);
DEC(ps);
if (isDouble(ps)) {
/* numeric variable: bit shift by integer amount */
Expand Down Expand Up @@ -1494,7 +1494,7 @@ epicsShareFunc long
INC(ps);
ps->s = &(ps->local_string[0]);
s = ps->s;
for (i=0; (i<SCALC_STRING_SIZE-1) && *post; )
for (i=0; (i<SCALC_STRING_SIZE-1) && *post; i++)
*s++ = (char)*post++;
*s = '\0';
/* skip to end of string, if we haven't already */
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