common/json: fix out-of-bounds slice in the comment scanner - #108
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common/json: fix out-of-bounds slice in the comment scanner#108AlexandrKhromov2005 wants to merge 1 commit into
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skipJSONString advances i by 2 on a backslash escape; when the backslash is the
last byte of the input, i is pushed past len(data) and returned unchanged. A
caller then slices data[keyStart:keyEnd] with keyEnd > len(data), panicking with
"slice bounds out of range". This is reachable from any untrusted JSON parsed by
the comment-aware decoder (e.g. a sing-box config or rule-set), e.g. the 12-byte
input {0000000#00000\n\ crashes it.
Clamp the returned index to len(data). Add FuzzUnmarshalExtended.
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common/json: fix out-of-bounds slice in the comment scanner
skipJSONStringadvancesiby 2 on a backslash escape. When the backslash is the last byte ofthe input,
iis pushed pastlen(data)and returned unchanged; a caller then slicesdata[keyStart:keyEnd]withkeyEnd > len(data)and panics withslice bounds out of range.This is reachable from any untrusted JSON parsed by the comment-aware decoder (
UnmarshalExtended),e.g. a sing-box config or rule-set. Found by fuzzing sing-box config parsing; the 12-byte input
{0000000#00000\n\is enough to crash it.Fix
Clamp the returned index to
len(data). AddsFuzzUnmarshalExtended; existing tests pass.