Validate Buffer#read_frame argument to prevent SEGV#97
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read_frame passed its data argument straight to buffer_read_frame(), which appends to it via rb_str_cat() without any type check. A non-String argument was dereferenced as a char* and crashed the VM instead of raising an error. Coerce data with StringValue() and reject frozen strings with rb_str_modify(), matching the validation already done by #append and #prepend. Add specs covering non-String, frozen String, and to_str coercion cases.
Watson1978
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Summary
Buffer#read_framepassed itsdataargument straight to the internalbuffer_read_frame(), which appends to it viarb_str_cat()without any type check. Whendatais not a String, the immediate VALUE is dereferenced as achar*insiderb_str_cat, crashing the whole VM with a SEGV instead of raising a Ruby exception.Every other entry point (
#append,#prepend) already coerces its argument to a String, soread_framewas the only unguarded path.Fix
Coerce
datawithStringValue()and reject frozen strings withrb_str_modify()(sincedatais used as an output buffer that gets written to). This turns the crash into a properTypeError/FrozenError, matching the behavior of#appendand#prepend.No compatibility impact: existing callers that pass a valid mutable String are unaffected; only misuse is now raised as an exception.
Tests
Added specs to
spec/iobuffer_spec.rbcovering:TypeError(no more SEGV)FrozenError#to_strare coerced correctlyAll buffer specs pass locally.