From: Junio C Hamano <gitster@pobox.com>
To: git@vger.kernel.org
Subject: [PATCH] clone: plug a miniscule leak
Date: Sat, 30 Apr 2022 22:17:15 -0700 [thread overview]
Message-ID: <xmqqlevl4ysk.fsf@gitster.g> (raw)
The remote_name variable is first assigned a copy of the value of
the "clone.defaultremotename" configuration variable and then by the
value of the "--origin" command line option. The former is prepared
to see multiple instances of the variable by freeing the current
value of the variable before a copy of the newly discovered value
gets assigned to it. The latter blindly assigned a copy of the new
value to it, thereby leaking the value read from the configuration.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
This was discovered by a recently removed bogus coccinelle
rewrite rule---if you apply an incorrect change suggested by the
bogus rewrite rule to unconditionally assign to remote_name a
copy of option_origin, or NULL, the value read from the
configuration would be lost and never be used, thereby breaking
a test to ensure the configuration is used, instead of the
default remote nickname "origin".
Perhaps a Coccinelle rule like this might have caught similar
leaks:
@@
expression E;
expression V;
@@
- if (E)
- V = xstrdup(E);
+ if (E) {
+ free(V);
+ V = xstrdup(E);
+ }
The fact that the result of xstrdup() is assigned to V is that V
is meant to hold a pointer to an allocated piece of memory.
With the preimage of the above semantic patch, it is reasonable
to expect that V may be initialized to NULL or may be holding a
pointer to a piece of allocated memory when the control reaches
here, because otherwise, V will be either need to be freed (when
E was not NULL, in which case we assigned the result of
xstrdup() to it) or V has garbage that cannot be freed later.
builtin/clone.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git c/builtin/clone.c w/builtin/clone.c
index 5231656379..194d50f75f 100644
--- c/builtin/clone.c
+++ w/builtin/clone.c
@@ -1106,8 +1106,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
* apply the remote name provided by --origin only after this second
* call to git_config, to ensure it overrides all config-based values.
*/
- if (option_origin != NULL)
+ if (option_origin != NULL) {
+ free(remote_name);
remote_name = xstrdup(option_origin);
+ }
if (remote_name == NULL)
remote_name = xstrdup("origin");
next reply other threads:[~2022-05-01 5:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-01 5:17 Junio C Hamano [this message]
2022-05-02 13:43 ` [PATCH] clone: plug a miniscule leak Derrick Stolee
2022-05-02 17:12 ` Junio C Hamano
2022-05-02 20:39 ` Philip Oakley
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