[Xen-devel] Xenstored: eliminate double free and fixes for memory leak

["Peter Teoh" <htmldeveloper@xxxxxxxxx>]

Please review.   This patch fixes a few problems:

a.   In handle_input(), which is called from main() in
xenstored_core.c, the conn->in is freed when there is no error, but
conn is freed when there is error.   This is inconsistent.  Moreover,
the conn is freed again upon exit from handle_input(), inside the
main.

b.   Another problem is that perms_to_strings() returned a allocated
memory (via realloc()).   The only time the value is returned is in
do_get_perms(), but immediately after send_reply(), the pointer is
immediately thrown away, resulting in a memory leak condition, as
send_reply() does not free any memory.

c.   Many of the functions like read_node(), get_parent(),
talloc_asprintf() etc all will allocate memory and return a pointer
when memory is allocated, but many times these are not freed.

Another problem identified but which I cannot fix, is that
create_hashtable() can return NULL in low memory condition.   But this
is not checked in the recursive function check_store_().   There is no
value to specify error or not in the return value of check_store_()
(declared as void).   May be we should change this to unsigned int or
something like that, so that error condition can be returned?

I am still making changes to the same file, but was hesitant to
incorporate so many changes as it will make the review more difficult.

I will submit these further changes in the next posting.

Attachment: eliminate_double_free_and_mem_leak.patch
Description: Text Data

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