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ls-config: fix stack overflow printing large floats in read_config - #306
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read_config() printed float values with sprintf("%f") into a 256-byte
stack buffer. %f never switches to exponent notation, so a value such as
1e300 in the config file expands to 308 characters and overruns it. This
hit scalar floats as well as float elements of arrays and lists.
Grow the buffer so any double fits (-DBL_MAX needs 318 bytes) and bound
the three float writes with snprintf(). test_float_overflow.c reads each
case back through read_config() and aborts under ASan without the fix.
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read_config()prints floats withsprintf(buffer, "%f", ...)into a 256-byte stack buffer, and%fnever falls back to exponent notation, so a config value likex = 1e300;(as a scalar, array element or list element) expands to 308 chars and overruns it; the buffer now fits any double (-DBL_MAXneeds 318 bytes), the three float writes usesnprintf(), andtest_float_overflow.ccovers all three paths the same waytest_sinp_overflow.cdoes.