Hi Christian ! On Sat, 29 Apr 2023 11:25:33 +0200 Christian Schoenebeck <qemu_...@crudebyte.com> wrote:
> Free allocated directory entries in v9fs_rreaddir() if argument > `entries` was passed as NULL, to avoid a memory leak. It is > explicitly allowed by design for `entries` to be NULL. [1] > > [1] https://lore.kernel.org/all/1690923.g4PEXVpXuU@silver > > Reported-by: Coverity (CID 1487558) > Signed-off-by: Christian Schoenebeck <qemu_...@crudebyte.com> > --- Good catch Coverity ! :-) Reviewed-by: Greg Kurz <gr...@kaod.org> I still have a suggestion. See below. > tests/qtest/libqos/virtio-9p-client.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/tests/qtest/libqos/virtio-9p-client.c > b/tests/qtest/libqos/virtio-9p-client.c > index e4a368e036..b8adc8d4b9 100644 > --- a/tests/qtest/libqos/virtio-9p-client.c > +++ b/tests/qtest/libqos/virtio-9p-client.c > @@ -594,6 +594,8 @@ void v9fs_rreaddir(P9Req *req, uint32_t *count, uint32_t > *nentries, > { > uint32_t local_count; > struct V9fsDirent *e = NULL; > + /* only used to avoid a leak if entries was NULL */ > + struct V9fsDirent *unused_entries = NULL; > uint16_t slen; > uint32_t n = 0; > > @@ -612,6 +614,8 @@ void v9fs_rreaddir(P9Req *req, uint32_t *count, uint32_t > *nentries, > e = g_new(struct V9fsDirent, 1); > if (entries) { > *entries = e; > + } else { > + unused_entries = e; > } > } else { > e = e->next = g_new(struct V9fsDirent, 1); This is always allocating and chaining a new entry even though it isn't needed in the entries == NULL case. > @@ -628,6 +632,7 @@ void v9fs_rreaddir(P9Req *req, uint32_t *count, uint32_t > *nentries, > *nentries = n; > } > > + v9fs_free_dirents(unused_entries); This is going to loop again on all entries to free them. > v9fs_req_free(req); > } > If this function is to be called one day with an enormous number of entries and entries == NULL case, this might not scale well. What about only allocating a single entry in this case ? E.g. @@ -593,7 +593,7 @@ void v9fs_rreaddir(P9Req *req, uint32_t *count, uint32_t *nentries, struct V9fsDirent **entries) { uint32_t local_count; - struct V9fsDirent *e = NULL; + g_autofree struct V9fsDirent *e = NULL; uint16_t slen; uint32_t n = 0; @@ -611,10 +611,12 @@ void v9fs_rreaddir(P9Req *req, uint32_t *count, uint32_t *nentries, if (!e) { e = g_new(struct V9fsDirent, 1); if (entries) { - *entries = e; + *entries = g_steal_pointer(e); } } else { - e = e->next = g_new(struct V9fsDirent, 1); + if (entries) { + e = e->next = g_new(struct V9fsDirent, 1); + } } e->next = NULL; /* qid[13] offset[8] type[1] name[s] */
