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[PATCH] config: do not leak excludes_file

From
Junio C Hamano <gitster@pobox.com>
Date
Apr 6, 2024, 18:11 UTC
Message-ID
<xmqqttkeicov.fsf@gitster.g>

The excludes_file variable is marked "const char *", but all the assignments to it are made with a piece of memory allocated just for it, and the variable is responsible for owning it.

When "core.excludesfile" is read, the code just lost the previous value, leaking memory. Plug it.

The real problem is that the variable is mistyped; our convention is to never make a variable that owns the piece of memory pointed by it as "const". Fixing that would reduce the chance of this kind of bug happening, and also would make it unnecessary to cast the constness away while free()ing it, but that would be a much larger follow-up effort.

Reported-by: Rubén Justo <rjusto@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 config.c         | 4 +++-
 t/t7300-clean.sh | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/config.c b/config.c
index eebce8c7e0..ae3652b08f 100644
--- a/config.c
+++ b/config.c
@@ -1584,8 +1584,10 @@ static int git_default_core_config(const char *var, const char *value,
 	if (!strcmp(var, "core.askpass"))
 		return git_config_string(&askpass_program, var, value);
 
-	if (!strcmp(var, "core.excludesfile"))
+	if (!strcmp(var, "core.excludesfile")) {
+		free((char *)excludes_file);
 		return git_config_pathname(&excludes_file, var, value);
+	}
 
 	if (!strcmp(var, "core.whitespace")) {
 		if (!value)
diff --git a/t/t7300-clean.sh b/t/t7300-clean.sh
index 1f7201eb60..0aae0dee67 100755
--- a/t/t7300-clean.sh
+++ b/t/t7300-clean.sh
@@ -5,6 +5,7 @@
 
 test_description='git clean basic tests'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 git config clean.requireForce no
-- 
2.44.0-501-g19981daefd
Next: Junio C Hamano
Message 1 of 23 in “config: do not leak excludes_file”
  1. config: do not leak excludes_fileJunio C Hamano, Apr 6, 2024
  2. [WIP] git_config_pathname() leakfixJunio C Hamano, Apr 6, 2024
  3. 0/12 git_config_string() considered harmfulJeff King, Apr 7, 2024
  4. 01/11 config: make sequencer.c's git_config_string_dup() publicJeff King, Apr 7, 2024
  5. 02/11 config: add git_config_pathname_dup()Jeff King, Apr 7, 2024
  6. 03/11 config: prefer git_config_string_dup() for temp variablesJeff King, Apr 7, 2024
  7. Eric SunshineApr 7, 2024
  8. Jeff KingApr 7, 2024
  9. 04/11 config: use git_config_string_dup() for open-coded equivalentsJeff King, Apr 7, 2024
  10. 05/11 config: use git_config_string_dup() to fix leaky open codingJeff King, Apr 7, 2024
  11. 06/11 config: use git_config_string() in easy casesJeff King, Apr 7, 2024
  12. Eric SunshineApr 7, 2024
  13. Jeff KingApr 7, 2024
  14. 07/11 config: use git_config_pathname_dup() in easy casesJeff King, Apr 7, 2024
  15. 08/11 http: use git_config_string_dup()Jeff King, Apr 7, 2024
  16. 09/11 merge: use git_config_string_dup() for pull strategiesJeff King, Apr 7, 2024
  17. 10/11 userdiff: use git_config_string_dup() when we canJeff King, Apr 7, 2024
  18. 11/11 blame: use "dup" string_list for ignore-revs filesJeff King, Apr 7, 2024
  19. Eric SunshineApr 7, 2024
  20. Jeff KingApr 7, 2024
  21. Rubén JustoApr 7, 2024
  22. Jeff KingApr 8, 2024
  23. Rubén JustoApr 11, 2024

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