Messages in this thread | | | Date | Thu, 29 Sep 2022 19:29:33 +0900 | From | Dominique Martinet <> | Subject | Re: [PATCH 2/2] 9p: destroy client in symmetric order |
| |
Leon Romanovsky wrote on Thu, Sep 29, 2022 at 12:37:56PM +0300: > Make sure that all variables are initialized and released in correct > order.
Haven't tried running or compiling, comments out of my head that might be wrong below
> > Reported-by: syzbot+de52531662ebb8823b26@syzkaller.appspotmail.com
You're adding this report tag but I don't see how you fix that failure. What you need is p9_tag_cleanup(clnt) from p9_client_destroy -- I assume this isn't possible for any fid to be allocated at this point so the fid destroying loop is -probably- optional.
I would assume it is needed from p9_client_version failures.
> Signed-off-by: Leon Romanovsky <leon@kernel.org> > --- > net/9p/client.c | 37 ++++++++++++------------------------- > 1 file changed, 12 insertions(+), 25 deletions(-) > > diff --git a/net/9p/client.c b/net/9p/client.c > index aaa37b07e30a..8277e33506e7 100644 > --- a/net/9p/client.c > +++ b/net/9p/client.c > @@ -179,7 +179,6 @@ static int parse_opts(char *opts, struct p9_client *clnt) > goto free_and_return; > } > > - v9fs_put_trans(clnt->trans_mod);
Pretty sure you'll be "leaking transports" if someone tries to pass trans=foo multiple times; this can't be removed...(continues below)...
> clnt->trans_mod = v9fs_get_trans_by_name(s); > if (!clnt->trans_mod) { > pr_info("Could not find request transport: %s\n", > @@ -187,7 +186,7 @@ static int parse_opts(char *opts, struct p9_client *clnt) > ret = -EINVAL; > } > kfree(s); > - break; > + goto free_and_return;
... unless you also break the whole parsing, with this asking for -o trans=virtio,msize=1M will just ignore the msize argument. (or anything else that follows)
I appreciate that you're trying to avoid the get_default_trans below, but unless you just remember the last string and try to get it get/put trans is the most straight forward way to go.
(Note you just got me to try weird parsing and my old version was double-puting these modules because of the put_trans below in this function echoes with the client destroy. That'd just require removing the put here though (or nulling after put), yet another invariant I had wrongly assumed... Anyway.)
> case Opt_legacy: > clnt->proto_version = p9_proto_legacy; > break; > @@ -211,9 +210,14 @@ static int parse_opts(char *opts, struct p9_client *clnt) > } > } > > + clnt->trans_mod = v9fs_get_default_trans(); > + if (!clnt->trans_mod) { > + ret = -EPROTONOSUPPORT; > + p9_debug(P9_DEBUG_ERROR, > + "No transport defined or default transport\n"); > + } > + > free_and_return: > - if (ret) > - v9fs_put_trans(clnt->trans_mod);
(oh, and if you parse options after trans= you'll need some sort of escape hatch here...)
> kfree(tmp_options); > return ret; > } > @@ -956,19 +960,14 @@ static int p9_client_version(struct p9_client *c) > > struct p9_client *p9_client_create(const char *dev_name, char *options) > { > - int err; > struct p9_client *clnt; > char *client_id; > + int err = 0; > > - err = 0; > - clnt = kmalloc(sizeof(*clnt), GFP_KERNEL); > + clnt = kzalloc(sizeof(*clnt), GFP_KERNEL); > if (!clnt) > return ERR_PTR(-ENOMEM); > > - clnt->trans_mod = NULL; > - clnt->trans = NULL; > - clnt->fcall_cache = NULL; > - > client_id = utsname()->nodename; > memcpy(clnt->name, client_id, strlen(client_id) + 1); > > @@ -980,16 +979,6 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) > if (err < 0) > goto free_client; > > - if (!clnt->trans_mod) > - clnt->trans_mod = v9fs_get_default_trans(); > - > - if (!clnt->trans_mod) { > - err = -EPROTONOSUPPORT; > - p9_debug(P9_DEBUG_ERROR, > - "No transport defined or default transport\n"); > - goto free_client; > - } > - > p9_debug(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n", > clnt, clnt->trans_mod, clnt->msize, clnt->proto_version); > > @@ -1044,9 +1033,8 @@ void p9_client_destroy(struct p9_client *clnt) > > p9_debug(P9_DEBUG_MUX, "clnt %p\n", clnt); > > - if (clnt->trans_mod) > - clnt->trans_mod->close(clnt); > - > + kmem_cache_destroy(clnt->fcall_cache);
Pretty sure kmem_cache used to issue a warning when we did that (hence me trying to move it up on allocation) -- at this point there can still be in flight requests we need to finish freeing before we can destroy the cache.
> + clnt->trans_mod->close(clnt); > v9fs_put_trans(clnt->trans_mod); > > idr_for_each_entry(&clnt->fids, fid, id) { > @@ -1056,7 +1044,6 @@ void p9_client_destroy(struct p9_client *clnt) > > p9_tag_cleanup(clnt); > > - kmem_cache_destroy(clnt->fcall_cache); > kfree(clnt); > } > EXPORT_SYMBOL(p9_client_destroy);
-- Dominique
| |