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CDRIVER-5681 Address potential buffer overflow when writing null terminator after decimal128 significand digits #1719

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Merged
merged 8 commits into from
Sep 10, 2024
Merged

CDRIVER-5681 Address potential buffer overflow when writing null terminator after decimal128 significand digits #1719

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72325a2
Address integer overflow when writing null terminator for decimal128 …
eramongodb Sep 5, 2024
4b24fd7
Replace unnecessary ptrdiff_t with int
eramongodb Sep 5, 2024
7ceacb4
Add test case for truncated significand
eramongodb Sep 6, 2024
f48e687
BSON_ASSERT + strcmp -> ASSERT_CMPSTR
eramongodb Sep 6, 2024
1a8e3f1
Add test case for untruncated significand
eramongodb Sep 6, 2024
8472ad0
Extend significand truncation tests to assert inexact rounding errors
eramongodb Sep 9, 2024
8cfdff1
Assert return value of bson_decimal128_from_string
eramongodb Sep 9, 2024
3e7270c
BSON_ASSERT -> ASSERT
eramongodb Sep 9, 2024
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7 changes: 5 additions & 2 deletions src/libbson/src/bson/bson-decimal128.c
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Original file line number Diff line number Diff line change
Expand Up @@ -282,8 +282,11 @@ bson_decimal128_to_string (const bson_decimal128_t *dec, /* IN */
} else {
int32_t radix_position = significand_digits + exponent;

// Reserve space for null terminator.
const int available_bytes = BSON_DECIMAL128_STRING - 1;

if (radix_position > 0) { /* non-zero digits before radix */
for (int32_t i = 0; i < radix_position && (str_out - str) < BSON_DECIMAL128_STRING; i++) {
for (int32_t i = 0; i < radix_position && (str_out - str) < available_bytes; i++) {
*(str_out++) = *(significand_read++) + '0';
}
} else { /* leading zero before radix point */
Expand All @@ -296,7 +299,7 @@ bson_decimal128_to_string (const bson_decimal128_t *dec, /* IN */
}

for (uint32_t i = 0; bson_cmp_greater_us (significand_digits - i, BSON_MAX (radix_position - 1, 0)) &&
(str_out - str) < BSON_DECIMAL128_STRING;
(str_out - str) < available_bytes;
i++) {
*(str_out++) = *(significand_read++) + '0';
}
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