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Avoid reading past datum end when parsing JSON.

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Several loops in the JSON parser examined a byte in memory just before
checking whether its address was in-bounds, so they could read one byte
beyond the datum's allocation.  A SIGSEGV is possible.  New in 9.3, so
no back-patch.
This commit is contained in:
Noah Misch 2013-06-12 19:51:12 -04:00
parent 3a5d0c5533
commit 66008564f8
1 changed files with 13 additions and 8 deletions
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21
src/backend/utils/adt/json.c
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@ -598,7 +598,7 @@ json_lex(JsonLexContext *lex)
* the whole word as an unexpected token, rather than just
* some unintuitive prefix thereof.
*/
for (p = s; JSON_ALPHANUMERIC_CHAR(*p) && p - s < lex->input_length - len; p++)
for (p = s; p - s < lex->input_length - len && JSON_ALPHANUMERIC_CHAR(*p); p++)
/* skip */ ;
/*
@ -651,16 +651,21 @@ json_lex_string(JsonLexContext *lex)
if (lex->strval != NULL)
resetStringInfo(lex->strval);
Assert(lex->input_length > 0);
s = lex->token_start;
len = lex->token_start - lex->input;
len++;
for (s = lex->token_start + 1; *s != '"'; s++, len++)
for (;;)
{
s++;
len++;
/* Premature end of the string. */
if (len >= lex->input_length)
{
lex->token_terminator = s;
report_invalid_token(lex);
}
else if (*s == '"')
break;
else if ((unsigned char) *s < 32)
{
/* Per RFC4627, these characters MUST be escaped. */
@ -921,7 +926,7 @@ json_lex_number(JsonLexContext *lex, char *s)
{
s++;
len++;
} while (*s >= '0' && *s <= '9' && len < lex->input_length);
} while (len < lex->input_length && *s >= '0' && *s <= '9');
}
else
error = true;
@ -939,7 +944,7 @@ json_lex_number(JsonLexContext *lex, char *s)
{
s++;
len++;
} while (*s >= '0' && *s <= '9' && len < lex->input_length);
} while (len < lex->input_length && *s >= '0' && *s <= '9');
}
}
@ -970,7 +975,7 @@ json_lex_number(JsonLexContext *lex, char *s)
* here should be considered part of the token for error-reporting
* purposes.
*/
for (p = s; JSON_ALPHANUMERIC_CHAR(*p) && len < lex->input_length; p++, len++)
for (p = s; len < lex->input_length && JSON_ALPHANUMERIC_CHAR(*p); p++, len++)
error = true;
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = p;
@ -1138,8 +1143,8 @@ report_json_context(JsonLexContext *lex)
line_number = 1;
for (;;)
{
/* Always advance over newlines (context_end test is just paranoia) */
if (*context_start == '\n' && context_start < context_end)
/* Always advance over newlines */
if (context_start < context_end && *context_start == '\n')
{
context_start++;
line_start = context_start;