From fc896f45d6d859d9da52106cf42dc01dce88c224 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 7 Jun 2021 14:15:25 -0400 Subject: Fix incautious handling of possibly-miscoded strings in client code. An incorrectly-encoded multibyte character near the end of a string could cause various processing loops to run past the string's terminating NUL, with results ranging from no detectable issue to a program crash, depending on what happens to be in the following memory. This isn't an issue in the server, because we take care to verify the encoding of strings before doing any interesting processing on them. However, that lack of care leaked into client-side code which shouldn't assume that anyone has validated the encoding of its input. Although this is certainly a bug worth fixing, the PG security team elected not to regard it as a security issue, primarily because any untrusted text should be sanitized by PQescapeLiteral or the like before being incorporated into a SQL or psql command. (If an app fails to do so, the same technique can be used to cause SQL injection, with probably much more dire consequences than a mere client-program crash.) Those functions were already made proof against this class of problem, cf CVE-2006-2313. To fix, invent PQmblenBounded() which is like PQmblen() except it won't return more than the number of bytes remaining in the string. In HEAD we can make this a new libpq function, as PQmblen() is. It seems imprudent to change libpq's API in stable branches though, so in the back branches define PQmblenBounded as a macro in the files that need it. (Note that just changing PQmblen's behavior would not be a good idea; notably, it would completely break the escaping functions' defense against this exact problem. So we just want a version for those callers that don't have any better way of handling this issue.) Per private report from houjingyi. Back-patch to all supported branches. --- src/bin/scripts/common.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'src/bin/scripts/common.c') diff --git a/src/bin/scripts/common.c b/src/bin/scripts/common.c index 7f4b635571d..bb52e6b9ffe 100644 --- a/src/bin/scripts/common.c +++ b/src/bin/scripts/common.c @@ -23,6 +23,8 @@ #include "fe_utils/string_utils.h" +#define PQmblenBounded(s, e) strnlen(s, PQmblen(s, e)) + static PGcancel *volatile cancelConn = NULL; bool CancelRequested = false; @@ -300,7 +302,7 @@ splitTableColumnsSpec(const char *spec, int encoding, cp++; } else - cp += PQmblen(cp, encoding); + cp += PQmblenBounded(cp, encoding); } *table = pg_strdup(spec); (*table)[cp - spec] = '\0'; /* no strndup */ -- cgit v1.2.3