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> I found a problem with PQescapeString (I think). Since it escapes

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> null bytes to be literally '\0', the following can happen:
> 1. User inputs string value as "<null byte>##" where ## are digits in the
> range of 0 to 7.
> 2. PQescapeString converts this to "\0##"
> 3. Escaped string is used in a context that causes "\0##" to be evaluated as
> an octal escape sequence.

I agree that this is a problem, though it is not possible to do
anything harmful with it.  In addition, it only occurs if there are
any NUL characters in its input, which is very unlikely if you are
using C strings.

The patch below addresses the issue by removing escaping of \0
characters entirely.

> If the goal is to "safely" encode null bytes, and preserve the rest of the
> string as it was entered, I think the null bytes should be escaped as \\000
> (note that if you simply use \000 the same string truncation problem
> occurs).

We can't do that, this would require 4n + 1 bytes of storage for the
result, breaking the interface.

Florian Weimer
This commit is contained in:
Bruce Momjian 2001-09-13 17:00:34 +00:00
parent 351a0c1736
commit 54549d8dc4
2 changed files with 3 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/interfaces/jdbc/org/postgresql/jdbc2/ResultSet.java
View File

@ -1396,7 +1396,7 @@ public class ResultSet extends org.postgresql.ResultSet implements java.sql.Resu
if (s != null)
{
int c = s.charAt(0);
return ((c == 't') || (c == 'T'));
return ((c == 't') || (c == 'T') || (c == '1'));
}
return false; // SQL NULL
}

11
src/interfaces/libpq/fe-exec.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.110 2001/09/07 22:02:32 momjian Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.111 2001/09/13 17:00:34 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -59,7 +59,7 @@ static int getNotice(PGconn *conn);
/* ---------------
* Escaping arbitrary strings to get valid SQL strings/identifiers.
*
* Replaces "\\" with "\\\\", "\0" with "\\0", and "'" with "''".
* Replaces "\\" with "\\\\" and "'" with "''".
* length is the length of the buffer pointed to by
* from. The buffer at to must be at least 2*length + 1 characters
* long. A terminating NUL character is written.
@ -75,13 +75,6 @@ PQescapeString (char *to, const char *from, size_t length)
while (remaining > 0) {
switch (*source) {
case '\0':
*target = '\\';
target++;
*target = '0';
/* target and remaining are updated below. */
break;
case '\\':
*target = '\\';
target++;