Avoid possible segfault in psql's tab completion.

tglsfdc · tglsfdc · commit 95eb4cd4ff06 · 2024-10-10T16:17:38.000-04:00
Fix oversight in bd1276a: the "words_after_create" stanza in psql_completion() requires previous_words_count > 0, since it uses prev_wd. This condition was formerly assured by the if-else chain above it, but no more. If there were no previous words then we'd dereference an uninitialized pointer, possibly causing a segfault. Report and patch by Anthonin Bonnefoy. Discussion: https://postgr.es/m/CAO6_XqrSRE7c_i+D7Hm07K3+6S0jTAmMr60RY41XzaA29Ae5uA@mail.gmail.com
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
@@ -2024,7 +2024,7 @@ psql_completion(const char *text, int start, int end)
 	 * check if that was the previous word. If so, execute the query to get a
 	 * list of them.
 	 */
-	if (matches == NULL)
+	if (matches == NULL && previous_words_count > 0)
 	{
 		const pgsql_thing_t *wac;
 

Original file line number	Diff line number	Diff line change
`@@ -2024,7 +2024,7 @@ psql_completion(const char *text, int start, int end)`
`2024`	`2024`	`* check if that was the previous word. If so, execute the query to get a`
`2025`	`2025`	`* list of them.`
`2026`	`2026`	`*/`
`2027`		`- if (matches == NULL)`
	`2027`	`+ if (matches == NULL && previous_words_count > 0)`
`2028`	`2028`	`{`
`2029`	`2029`	`const pgsql_thing_t *wac;`
`2030`	`2030`