Handle NaN in json_int() (undefined double->int cast)#541
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gigioneggiando wants to merge 1 commit into
Open
Handle NaN in json_int() (undefined double->int cast)#541gigioneggiando wants to merge 1 commit into
gigioneggiando wants to merge 1 commit into
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json_number() is a thin strtod() wrapper, which per C99 accepts "NaN" and "Infinity". In json_int() the clamps `v < 0` and `v > INT_MAX` are both false for NaN (every NaN comparison is false), so NaN reaches the (int)v cast, which is undefined behavior (on x86-64 it yields INT_MIN). Replace `if (v < 0)` with `if (!(v >= 0))`, which folds NaN and negatives to 0; +/-Infinity are still handled by the two clamps.
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Summary
json_number()is a thinstrtod()wrapper, which per C99 accepts"NaN"and"Infinity". Injson_int()the two clampsv < 0andv > INT_MAXare both false for NaN (every comparison against NaN is false), so a NaN value reaches the(int)vcast, which is undefined behavior for NaN (on x86-64 it yieldsINT_MIN).So a request field like
{"max_tokens": NaN}produces an out-of-range integer conversion rather than being rejected/clamped.Fix
Replace
if (v < 0) v = 0;withif (!(v >= 0)) v = 0;, which folds NaN (and negatives) to 0.+Infinity/-Infinityremain handled by the existing clamps. One-line change, no new dependency.Verification
Built under UBSan with
-fsanitize=float-cast-overflow, driving the realjson_int("NaN"):runtime error: nan is outside the range of representable values of type 'int'.0, no trap.Low severity (no memory corruption), found during a coordinated security review of ds4; a standalone offline PoC is available on request.