Set a hard limit on regular expression length #128
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* Grow the stack exponentially instead of linearly. * Use size_t instead of int for sizes. * Rename stack_num_objects() to stack_num_items() to reduce confusion between stack objects and objects on the stack.
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The effective limit on regular expression length today is slightly less than half the stack size, which is hardcoded to 10,240 entries. Due to a lack of input validation and persistent use of signed types, values much larger than that will cause TRE to overflow and either crash or misbehave instead of returning REG_ESPACE. * Define TRE_MAX_STACK to 1048576 and use that as our stack size limit. * Define TRE_MAX_RE to 65536 and refuse to compile a regular expression longer than that (in characters, not bytes). * Adjust the tests to handle the increased limit. * Since we make an effort to not crash when asked to compile a null regular expression, add tests to verify that we don't.
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The effective limit on regular expression length today is slightly less than half the stack size, which is hardcoded to 10,240 entries. Due to a lack of input validation and persistent use of signed types, values much larger than that will cause TRE to overflow and either crash or misbehave instead of returning
REG_ESPACE.This pull request increases the maximum stack size and sets a hard limit on regular expression length so we always return
REG_ESPACElong before we overflow.Note that this does not address matching, where TRE will misbehave if given a string longer than
INT_MAX. Fixing that will require significantly more work than fixing compilation did.