Many code paths will free a tree object's buffer and set it
to NULL after finishing with it in order to keep memory
usage down during a traversal. However, out of 8 sites that
do this, only one actually unsets the "parsed" flag back.
Those sites that don't are setting a trap for later users of
the tree object; even after calling parse_tree, the buffer
will remain NULL, causing potential segfaults.
It is not known whether this is triggerable in the current
code. Most commands do not do an in-memory traversal
followed by actually using the objects again. However, it
does not hurt to be safe for future callers.
In most cases, we can abstract this out to a
"free_tree_buffer" helper. However, there are two
exceptions:
1. The fsck code relies on the parsed flag to know that we
were able to parse the object at one point. We can
switch this to using a flag in the "flags" field.
2. The index-pack code sets the buffer to NULL but does
not free it (it is freed by a caller). We should still
unset the parsed flag here, but we cannot use our
helper, as we do not want to free the buffer.
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
This shouldn't have any behavior change, but I'd worry a bit that I
missed some case in builtin/fsck.c where the new HAS_OBJ flag would need
set.
builtin/fsck.c | 17 ++++++++---------
builtin/index-pack.c | 1 +
builtin/reflog.c | 3 +--
http-push.c | 3 +--
list-objects.c | 3 +--
reachable.c | 3 +--
revision.c | 3 +--
tree.c | 8 ++++++++
tree.h | 1 +
walker.c | 5 +----
10 files changed, 24 insertions(+), 23 deletions(-)
diff --git a/builtin/fsck.c b/builtin/fsck.c
index bb9a2cd..579fdcc 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -16,6 +16,7 @@
#define REACHABLE 0x0001
#define SEEN 0x0002
+#define HAS_OBJ 0x0004
static int show_root;
static int show_tags;
@@ -101,7 +102,7 @@ static int mark_object(struct object *obj, int type, void *data)
if (obj->flags & REACHABLE)
return 0;
obj->flags |= REACHABLE;
- if (!obj->parsed) {
+ if (!(obj->flags & HAS_OBJ)) {
if (parent && !has_sha1_file(obj->sha1)) {
printf("broken link from %7s %s\n",
typename(parent->type), sha1_to_hex(parent->sha1));
@@ -127,16 +128,13 @@ static int traverse_one_object(struct object *obj)
struct tree *tree = NULL;
if (obj->type == OBJ_TREE) {
- obj->parsed = 0;
tree = (struct tree *)obj;
if (parse_tree(tree) < 0)
return 1; /* error already displayed */
}
result = fsck_walk(obj, mark_object, obj);
- if (tree) {
- free(tree->buffer);
- tree->buffer = NULL;
- }
+ if (tree)
+ free_tree_buffer(tree);
return result;
}
@@ -178,7 +176,7 @@ static void check_reachable_object(struct object *obj)
* except if it was in a pack-file and we didn't
* do a full fsck
*/
- if (!obj->parsed) {
+ if (!(obj->flags & HAS_OBJ)) {
if (has_sha1_pack(obj->sha1))
return; /* it is in pack - forget about it */
printf("missing %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
@@ -306,8 +304,7 @@ static int fsck_obj(struct object *obj)
if (obj->type == OBJ_TREE) {
struct tree *item = (struct tree *) obj;
- free(item->buffer);
- item->buffer = NULL;
+ free_tree_buffer(item);
}
if (obj->type == OBJ_COMMIT) {
@@ -340,6 +337,7 @@ static int fsck_sha1(const unsigned char *sha1)
return error("%s: object corrupt or missing",
sha1_to_hex(sha1));
}
+ obj->flags |= HAS_OBJ;
return fsck_obj(obj);
}
@@ -352,6 +350,7 @@ static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
errors_found |= ERROR_OBJECT;
return error("%s: object corrupt or missing", sha1_to_hex(sha1));
}
+ obj->flags = HAS_OBJ;
return fsck_obj(obj);
}
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 79dfe47..20cf284 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -765,6 +765,7 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
if (obj->type == OBJ_TREE) {
struct tree *item = (struct tree *) obj;
item->buffer = NULL;
+ obj->parsed = 0;
}
if (obj->type == OBJ_COMMIT) {
struct commit *commit = (struct commit *) obj;
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 54184b3..ba27f7c 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -94,8 +94,7 @@ static int tree_is_complete(const unsigned char *sha1)
complete = 0;
}
}
- free(tree->buffer);
- tree->buffer = NULL;
+ free_tree_buffer(tree);
if (complete)
tree->object.flags |= SEEN;
diff --git a/http-push.c b/http-push.c
index 395a8cf..c13b441 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1330,8 +1330,7 @@ static struct object_list **process_tree(struct tree *tree,
break;
}
- free(tree->buffer);
- tree->buffer = NULL;
+ free_tree_buffer(tree);
return p;
}
diff --git a/list-objects.c b/list-objects.c
index 3dd4a96..c8c3463 100644
--- a/list-objects.c
+++ b/list-objects.c
@@ -123,8 +123,7 @@ static void process_tree(struct rev_info *revs,
cb_data);
}
strbuf_setlen(base, baselen);
- free(tree->buffer);
- tree->buffer = NULL;
+ free_tree_buffer(tree);
}
static void mark_edge_parents_uninteresting(struct commit *commit,
diff --git a/reachable.c b/reachable.c
index e7e6a1e..654a8c5 100644
--- a/reachable.c
+++ b/reachable.c
@@ -80,8 +80,7 @@ static void process_tree(struct tree *tree,
else
process_blob(lookup_blob(entry.sha1), p, &me, entry.path, cp);
}
- free(tree->buffer);
- tree->buffer = NULL;
+ free_tree_buffer(tree);
}
static void process_tag(struct tag *tag, struct object_array *p,
diff --git a/revision.c b/revision.c
index 518cd08..eb988ee 100644
--- a/revision.c
+++ b/revision.c
@@ -135,8 +135,7 @@ void mark_tree_uninteresting(struct tree *tree)
* We don't care about the tree any more
* after it has been marked uninteresting.
*/
- free(tree->buffer);
- tree->buffer = NULL;
+ free_tree_buffer(tree);
}
void mark_parents_uninteresting(struct commit *commit)
diff --git a/tree.c b/tree.c
index 62fed63..1cbf60e 100644
--- a/tree.c
+++ b/tree.c
@@ -225,6 +225,14 @@ int parse_tree(struct tree *item)
return parse_tree_buffer(item, buffer, size);
}
+void free_tree_buffer(struct tree *tree)
+{
+ free(tree->buffer);
+ tree->buffer = NULL;
+ tree->size = 0;
+ tree->object.parsed = 0;
+}
+
struct tree *parse_tree_indirect(const unsigned char *sha1)
{
struct object *obj = parse_object(sha1);
diff --git a/tree.h b/tree.h
index 69bcb5e..601ab9c 100644
--- a/tree.h
+++ b/tree.h
@@ -16,6 +16,7 @@ int parse_tree(struct tree *tree);
int parse_tree_buffer(struct tree *item, void *buffer, unsigned long size);
int parse_tree(struct tree *tree);
+void free_tree_buffer(struct tree *tree);
/* Parses and returns the tree in the given ent, chasing tags and commits. */
struct tree *parse_tree_indirect(const unsigned char *sha1);
diff --git a/walker.c b/walker.c
index be389dc..633596e 100644
--- a/walker.c
+++ b/walker.c
@@ -56,10 +56,7 @@ static int process_tree(struct walker *walker, struct tree *tree)
if (!obj || process(walker, obj))
return -1;
}
- free(tree->buffer);
- tree->buffer = NULL;
- tree->size = 0;
- tree->object.parsed = 0;
+ free_tree_buffer(tree);
return 0;
}
--
1.8.3.rc2.14.g7eee6b3
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html