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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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35
src/backend/utils/adt/pg_locale.c
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@ -1486,6 +1486,18 @@ init_icu_converter(void)
icu_converter = conv;
}
/*
* Convert a string in the database encoding into a string of UChars.
*
* The source string at buff is of length nbytes
* (it needn't be nul-terminated)
*
* *buff_uchar receives a pointer to the palloc'd result string, and
* the function's result is the number of UChars generated.
*
* The result string is nul-terminated, though most callers rely on the
* result length instead.
*/
int32_t
icu_to_uchar(UChar **buff_uchar, const char *buff, size_t nbytes)
{
@ -1494,18 +1506,30 @@ icu_to_uchar(UChar **buff_uchar, const char *buff, size_t nbytes)
init_icu_converter();
len_uchar = 2 * nbytes; /* max length per docs */
len_uchar = 2 * nbytes + 1; /* max length per docs */
*buff_uchar = palloc(len_uchar * sizeof(**buff_uchar));
status = U_ZERO_ERROR;
len_uchar = ucnv_toUChars(icu_converter, *buff_uchar, len_uchar, buff, nbytes, &status);
len_uchar = ucnv_toUChars(icu_converter, *buff_uchar, len_uchar,
buff, nbytes, &status);
if (U_FAILURE(status))
ereport(ERROR,
(errmsg("ucnv_toUChars failed: %s", u_errorName(status))));
return len_uchar;
}
/*
* Convert a string of UChars into the database encoding.
*
* The source string at buff_uchar is of length len_uchar
* (it needn't be nul-terminated)
*
* *result receives a pointer to the palloc'd result string, and the
* function's result is the number of bytes generated (not counting nul).
*
* The result string is nul-terminated.
*/
int32_t
icu_from_uchar(char **result, UChar *buff_uchar, int32_t len_uchar)
icu_from_uchar(char **result, const UChar *buff_uchar, int32_t len_uchar)
{
UErrorCode status;
int32_t len_result;
@ -1515,13 +1539,14 @@ icu_from_uchar(char **result, UChar *buff_uchar, int32_t len_uchar)
len_result = UCNV_GET_MAX_BYTES_FOR_STRING(len_uchar, ucnv_getMaxCharSize(icu_converter));
*result = palloc(len_result + 1);
status = U_ZERO_ERROR;
ucnv_fromUChars(icu_converter, *result, len_result, buff_uchar, len_uchar, &status);
len_result = ucnv_fromUChars(icu_converter, *result, len_result + 1,
buff_uchar, len_uchar, &status);
if (U_FAILURE(status))
ereport(ERROR,
(errmsg("ucnv_fromUChars failed: %s", u_errorName(status))));
return len_result;
}
#endif
#endif /* USE_ICU */
/*
* These functions convert from/to libc's wchar_t, *not* pg_wchar_t.