postgres.git / summary / log / commit / refs
commit 2a53db21eea7b4db0285f6a44a165def2d3f6531
Author: Thomas Munro <tmunro@postgresql.org>
Date: Wed Feb 04 12:04:24 2026 +0000
Fix encoding length for EUC_CN.
While EUC_CN supports only 1- and 2-byte sequences (CS0, CS1), the
mb<->wchar conversion functions allow 3-byte sequences beginning SS2,
SS3.
Change pg_encoding_max_length() to return 3, not 2, to close a
hypothesized buffer overrun if a corrupted string is converted to wchar
and back again in a newly allocated buffer. We might reconsider that in
master (ie harmonizing in a different direction), but this change seems
better for the back-branches.
Also change pg_euccn_mblen() to report SS2 and SS3 characters as having
length 3 (following the example of EUC_KR). Even though such characters
would not pass verification, it's remotely possible that invalid bytes
could be used to compute a buffer size for use in wchar conversion.
Security: CVE-2026-2006
Backpatch-through: 14
Author: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
src/common/wchar.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/src/common/wchar.c b/src/common/wchar.c
index 71f564abfad..aadad6ff116 100644
--- a/src/common/wchar.c
+++ b/src/common/wchar.c
@@ -266,12 +266,22 @@ pg_euccn2wchar_with_len(const unsigned char *from, pg_wchar *to, int len)
return cnt;
}
+/*
+ * mbverifychar does not accept SS2 or SS3 (CS2 and CS3 are not defined for
+ * EUC_CN), but mb2wchar_with_len does. Tell a coherent story for code that
+ * relies on agreement between mb2wchar_with_len and mblen. Invalid text
+ * datums (e.g. from shared catalogs) reach this.
+ */
static int
pg_euccn_mblen(const unsigned char *s)
{
int len;
- if (IS_HIGHBIT_SET(*s))
+ if (*s == SS2)
+ len = 3;
+ else if (*s == SS3)
+ len = 3;
+ else if (IS_HIGHBIT_SET(*s))
len = 2;
else
len = 1;
@@ -1916,7 +1926,7 @@ pg_encoding_set_invalid(int encoding, char *dst)
const pg_wchar_tbl pg_wchar_table[] = {
{pg_ascii2wchar_with_len, pg_wchar2single_with_len, pg_ascii_mblen, pg_ascii_dsplen, pg_ascii_verifychar, pg_ascii_verifystr, 1}, /* PG_SQL_ASCII */
{pg_eucjp2wchar_with_len, pg_wchar2euc_with_len, pg_eucjp_mblen, pg_eucjp_dsplen, pg_eucjp_verifychar, pg_eucjp_verifystr, 3}, /* PG_EUC_JP */
- {pg_euccn2wchar_with_len, pg_wchar2euc_with_len, pg_euccn_mblen, pg_euccn_dsplen, pg_euccn_verifychar, pg_euccn_verifystr, 2}, /* PG_EUC_CN */
+ {pg_euccn2wchar_with_len, pg_wchar2euc_with_len, pg_euccn_mblen, pg_euccn_dsplen, pg_euccn_verifychar, pg_euccn_verifystr, 3}, /* PG_EUC_CN */
{pg_euckr2wchar_with_len, pg_wchar2euc_with_len, pg_euckr_mblen, pg_euckr_dsplen, pg_euckr_verifychar, pg_euckr_verifystr, 3}, /* PG_EUC_KR */
{pg_euctw2wchar_with_len, pg_wchar2euc_with_len, pg_euctw_mblen, pg_euctw_dsplen, pg_euctw_verifychar, pg_euctw_verifystr, 4}, /* PG_EUC_TW */
{pg_eucjp2wchar_with_len, pg_wchar2euc_with_len, pg_eucjp_mblen, pg_eucjp_dsplen, pg_eucjp_verifychar, pg_eucjp_verifystr, 3}, /* PG_EUC_JIS_2004 */
[parent: 01de2e32df7b]