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Fix memory leakage in ICU encoding conversion, and other code review.

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Callers of icu_to_uchar() neglected to pfree the result string when done
with it.  This results in catastrophic memory leaks in varstr_cmp(),
because of our prevailing assumption that btree comparison functions don't
leak memory.  For safety, make all the call sites clean up leaks, though
I suspect that we could get away without it in formatting.c.  I audited
callers of icu_from_uchar() as well, but found no places that seemed to
have a comparable issue.

Add function API specifications for icu_to_uchar() and icu_from_uchar();
the lack of any thought-through specification is perhaps not unrelated
to the existence of this bug in the first place.  Fix icu_to_uchar()
to guarantee a nul-terminated result; although no existing caller appears
to care, the fact that it would have been nul-terminated except in
extreme corner cases seems ideally designed to bite someone on the rear
someday.  Fix ucnv_fromUChars() destCapacity argument --- in the worst
case, that could perhaps have led to a non-nul-terminated result, too.
Fix icu_from_uchar() to have a more reasonable definition of the function
result --- no callers are actually paying attention, so this isn't a live
bug, but it's certainly sloppily designed.  Const-ify icu_from_uchar()'s
input string for consistency.

That is not the end of what needs to be done to these functions, but
it's as much as I have the patience for right now.

Discussion: https://postgr.es/m/1955.1498181798@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2017-06-23 12:22:06 -04:00
parent 8be8510cf8
commit b6159202c9
5 changed files with 60 additions and 11 deletions
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3
src/backend/utils/adt/formatting.c
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@ -1561,6 +1561,7 @@ str_tolower(const char *buff, size_t nbytes, Oid collid)
len_conv = icu_convert_case(u_strToLower, mylocale,
&buff_conv, buff_uchar, len_uchar);
icu_from_uchar(&result, buff_conv, len_conv);
pfree(buff_uchar);
}
else
#endif
@ -1684,6 +1685,7 @@ str_toupper(const char *buff, size_t nbytes, Oid collid)
len_conv = icu_convert_case(u_strToUpper, mylocale,
&buff_conv, buff_uchar, len_uchar);
icu_from_uchar(&result, buff_conv, len_conv);
pfree(buff_uchar);
}
else
#endif
@ -1808,6 +1810,7 @@ str_initcap(const char *buff, size_t nbytes, Oid collid)
len_conv = icu_convert_case(u_strToTitle_default_BI, mylocale,
&buff_conv, buff_uchar, len_uchar);
icu_from_uchar(&result, buff_conv, len_conv);
pfree(buff_uchar);
}
else
#endif