Libclamav: harden XLM drawing group length checks#1707
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val-ms wants to merge 1 commit intoCisco-Talos:mainfrom
Open
Libclamav: harden XLM drawing group length checks#1707val-ms wants to merge 1 commit intoCisco-Talos:mainfrom
val-ms wants to merge 1 commit intoCisco-Talos:mainfrom
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The XLM drawing group parser grew a size_t length with BIFF record sizes before reallocating and copying the new chunk. That pattern looked like an integer overflow candidate, but the reported heap overflow is not reachable in practice because every growth step is immediately bounded by cli_max_realloc() and the BIFF record length cap, so the accumulated length cannot approach SIZE_MAX before the allocation limit stops processing. Add explicit pre-addition overflow checks at the two drawing group growth sites anyway. This keeps the existing control flow while making the arithmetic safety guarantee explicit and easier to audit. Credit: rinto CLAM-2935
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The XLM drawing group parser grew a size_t length with BIFF record sizes before reallocating and copying the new chunk. That pattern looked like an integer overflow candidate, but the reported heap overflow is not reachable in practice because every growth step is immediately bounded by cli_max_realloc() and the BIFF record length cap, so the accumulated length cannot approach SIZE_MAX before the allocation limit stops processing.
Add explicit pre-addition overflow checks at the two drawing group growth sites anyway. This keeps the existing control flow while making the arithmetic safety guarantee explicit and easier to audit.
Credit: rinto
CLAM-2935