Fix undefined behavior: invalid access of NULL ptr. #197
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Found with msan/asan analysis. Signed-off-by: Henner Zeller <[email protected]>
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With UBSAN, actually! It's UB to a) shift signed ints too much, and b) do non-trivial arithmetic on null pointers |
tkoeppe
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Nov 21, 2022
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| if ( p->pPars->fTruth ) | ||
| { | ||
| p->puTemp[0] = p->pPars->fTruth? ABC_ALLOC( unsigned, 8 * p->nTruth6Words[p->pPars->nLutSize] ) : NULL; | ||
| p->puTemp[1] = p->puTemp[0] + p->nTruth6Words[p->pPars->nLutSize]*2; | ||
| p->puTemp[2] = p->puTemp[1] + p->nTruth6Words[p->pPars->nLutSize]*2; | ||
| p->puTemp[3] = p->puTemp[2] + p->nTruth6Words[p->pPars->nLutSize]*2; | ||
| p->puTempW = p->pPars->fTruth? ABC_ALLOC( word, p->nTruth6Words[p->pPars->nLutSize] ) : NULL; | ||
| } | ||
| else | ||
| { | ||
| p->puTemp[0] = p->puTemp[1] = p->puTemp[2] = p->puTemp[3] = NULL; | ||
| p->puTempW = NULL; | ||
| } |
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I would welcome a somewhat careful review of this change. It wasn't immediately clear to me if in the case of !p->pPars->fTruth the various p->pu* pointers are actually unused. This case currently has undefined behaviour, but maybe there's some obscure pointer-to-offset logic somewhere else that actually needed those "null pointer increments"?
tkoeppe
reviewed
Nov 21, 2022
| if (quit) { | ||
| break; | ||
| } else { | ||
| path = ++cp; |
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The same mistake fixed twice in this patch: the increment must not happen after the last round of the loop.
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Found with msan analysis.