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authorRich Felker <dalias@aerifal.cx>2016-10-20 00:22:09 -0400
committerRich Felker <dalias@aerifal.cx>2016-10-20 00:22:09 -0400
commit167dfe9672c116b315e72e57a55c7769f180dffa (patch)
tree1e89b8b2ab2cb707f77e6c043f9171988d69fcd9 /INSTALL
parent70d2687d85c314963cf280759b23fd4573ff0d82 (diff)
downloadmusl-167dfe9672c116b315e72e57a55c7769f180dffa.tar.gz
fix integer overflows and uncaught EOVERFLOW in printf core
this patch fixes a large number of missed internal signed-overflow checks and errors in determining when the return value (output length) would exceed INT_MAX, which should result in EOVERFLOW. some of the issues fixed were reported by Alexander Cherepanov; others were found in subsequent review of the code. aside from the signed overflows being undefined behavior, the following specific bugs were found to exist in practice: - overflows computing length of floating point formats with huge explicit precisions, integer formats with prefix characters and huge explicit precisions, or string arguments or format strings longer than INT_MAX, resulted in wrong return value and wrong %n results. - literal width and precision values outside the range of int were misinterpreted, yielding wrong behavior in at least one well-defined case: string formats with precision greater than INT_MAX were sometimes truncated. - in cases where EOVERFLOW is produced, incorrect values could be written for %n specifiers past the point of exceeding INT_MAX. in addition to fixing these bugs, we now stop producing output immediately when output length would exceed INT_MAX, rather than continuing and returning an error only at the end.
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