From: "Martin Ågren" <martin.agren@gmail.com>
To: git@vger.kernel.org
Cc: Michael Haggerty <mhagger@alum.mit.edu>
Subject: [PATCH 2/2] refs/files-backend: fix memory leak in lock_ref_for_update
Date: Fri, 25 Aug 2017 20:49:16 +0200 [thread overview]
Message-ID: <fb9c0866cedac8c1d8fcf143641ebbee70d07ad7.1503496797.git.martin.agren@gmail.com> (raw)
In-Reply-To: <40c5e954dd84ff42552bccfea00144eecdbd1c7e.1503496797.git.martin.agren@gmail.com>
We hand over the "referent" string (buffer) to several different
functions, one of which would sometimes keep the raw pointer,
referent.buf. (When split_symref_update calls string_list_insert.) The
previous patch removed that behavior, so we can now safely release the
string buffer before returning.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
I appreciate Git's stance on memory leaks ("if we're about to exit or
die, why bother?") but this one feels different since
lock_ref_for_update is called in a loop rather deep down the call stack.
Feel free to tell me I'm wrong. Patch 1/2 does introduce some
malloc-churning. An alternative would be to call strbuf_release only
when we know it's safe, but that feels really ugly.
refs/files-backend.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 22daca2ba..6af07c404 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2252,7 +2252,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
struct strbuf referent = STRBUF_INIT;
int mustexist = (update->flags & REF_HAVE_OLD) &&
!is_null_oid(&update->old_oid);
- int ret;
+ int ret = 0;
struct ref_lock *lock;
files_assert_main_repository(refs, "lock_ref_for_update");
@@ -2264,7 +2264,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
ret = split_head_update(update, transaction, head_ref,
affected_refnames, err);
if (ret)
- return ret;
+ goto out;
}
ret = lock_raw_ref(refs, update->refname, mustexist,
@@ -2278,7 +2278,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
strbuf_addf(err, "cannot lock ref '%s': %s",
original_update_refname(update), reason);
free(reason);
- return ret;
+ goto out;
}
update->backend_data = lock;
@@ -2297,10 +2297,12 @@ static int lock_ref_for_update(struct files_ref_store *refs,
strbuf_addf(err, "cannot lock ref '%s': "
"error reading reference",
original_update_refname(update));
- return -1;
+ ret = -1;
+ goto out;
}
} else if (check_old_oid(update, &lock->old_oid, err)) {
- return TRANSACTION_GENERIC_ERROR;
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
}
} else {
/*
@@ -2314,13 +2316,15 @@ static int lock_ref_for_update(struct files_ref_store *refs,
referent.buf, transaction,
affected_refnames, err);
if (ret)
- return ret;
+ goto out;
}
} else {
struct ref_update *parent_update;
- if (check_old_oid(update, &lock->old_oid, err))
- return TRANSACTION_GENERIC_ERROR;
+ if (check_old_oid(update, &lock->old_oid, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
+ }
/*
* If this update is happening indirectly because of a
@@ -2357,7 +2361,8 @@ static int lock_ref_for_update(struct files_ref_store *refs,
"cannot update ref '%s': %s",
update->refname, write_err);
free(write_err);
- return TRANSACTION_GENERIC_ERROR;
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
} else {
update->flags |= REF_NEEDS_COMMIT;
}
@@ -2371,10 +2376,14 @@ static int lock_ref_for_update(struct files_ref_store *refs,
if (close_ref(lock)) {
strbuf_addf(err, "couldn't close '%s.lock'",
update->refname);
- return TRANSACTION_GENERIC_ERROR;
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
}
}
- return 0;
+
+out:
+ strbuf_release(&referent);
+ return ret;
}
/*
--
2.14.1.151.g45c1275a3.dirty
next prev parent reply other threads:[~2017-08-25 18:49 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-25 18:49 [PATCH 1/2] refs/files-backend: duplicate strings added to affected_refnames Martin Ågren
2017-08-25 18:49 ` Martin Ågren [this message]
2017-08-25 21:00 ` Junio C Hamano
2017-08-26 10:16 ` Martin Ågren
2017-08-28 8:06 ` Michael Haggerty
2017-08-28 10:09 ` Martin Ågren
2017-08-28 20:32 ` [PATCH v2 1/2] refs/files-backend: add longer-scoped copy of string to list Martin Ågren
2017-08-29 8:33 ` Michael Haggerty
2017-08-28 20:32 ` [PATCH v2 2/2] refs/files-backend: fix memory leak in lock_ref_for_update Martin Ågren
2017-08-29 8:39 ` Michael Haggerty
2017-08-29 10:41 ` Martin Ågren
2017-08-29 17:18 ` [PATCH v3 1/3] refs/files-backend: add longer-scoped copy of string to list Martin Ågren
2017-08-30 2:52 ` Michael Haggerty
2017-08-30 18:02 ` Martin Ågren
2017-09-05 10:02 ` Junio C Hamano
2017-09-05 17:24 ` Martin Ågren
2017-09-05 20:36 ` Jeff King
2017-09-05 21:26 ` Junio C Hamano
2017-09-06 18:12 ` Martin Ågren
2017-09-06 19:52 ` Junio C Hamano
2017-09-06 23:45 ` Jeff King
2017-09-09 6:57 ` [PATCH v4 0/4] Rerolling ma/split-symref-update-fix Martin Ågren
2017-09-09 6:57 ` [PATCH v4 1/4] refs/files-backend: add longer-scoped copy of string to list Martin Ågren
2017-09-09 6:57 ` [PATCH v4 2/4] refs/files-backend: fix memory leak in lock_ref_for_update Martin Ågren
2017-09-09 6:57 ` [PATCH v4 3/4] refs/files-backend: correct return value " Martin Ågren
2017-09-09 6:57 ` [PATCH v4 4/4] refs/files-backend: add `refname`, not "HEAD", to list Martin Ågren
2017-09-09 10:47 ` [PATCH v4 0/4] Rerolling ma/split-symref-update-fix Jeff King
2017-09-05 8:45 ` [PATCH v3 1/3] refs/files-backend: add longer-scoped copy of string to list Jeff King
2017-09-05 9:03 ` Michael Haggerty
2017-09-05 9:04 ` Jeff King
2017-08-29 17:18 ` [PATCH v3 2/3] refs/files-backend: fix memory leak in lock_ref_for_update Martin Ågren
2017-09-05 8:47 ` Jeff King
2017-09-05 17:28 ` Martin Ågren
2017-08-29 17:18 ` [PATCH v3 3/3] refs/files-backend: correct return value " Martin Ågren
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