4.17-stable review patch. If anyone has any objections, please let me know.
------------------ From: piaojun <[email protected]> [ Upstream commit c290fba8c4ce6530cd941ea14db5a4ac2f77183f ] In my testing, the second mount will fail after umounting successfully. The reason is that we put refcount of trans_mod in the correct case rather than the error case in parse_opts() at last. That will cause the refcount decrease to -1, and when we try to get trans_mod again in try_module_get(), we could only increase refcount to 0 which will cause failure as follows: parse_opts v9fs_get_trans_by_name try_module_get : return NULL to caller which cause error So we should put refcount of trans_mod in error case. Link: http://lkml.kernel.org/r/[email protected] Fixes: 9421c3e64137ec ("net/9p/client.c: fix potential refcnt problem of trans module") Signed-off-by: Jun Piao <[email protected]> Reviewed-by: Yiwen Jiang <[email protected]> Reviewed-by: Greg Kurz <[email protected]> Reviewed-by: Dominique Martinet <[email protected]> Tested-by: Dominique Martinet <[email protected]> Cc: Eric Van Hensbergen <[email protected]> Cc: Ron Minnich <[email protected]> Cc: Latchesar Ionkov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/9p/client.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/9p/client.c +++ b/net/9p/client.c @@ -228,7 +228,8 @@ static int parse_opts(char *opts, struct } free_and_return: - v9fs_put_trans(clnt->trans_mod); + if (ret) + v9fs_put_trans(clnt->trans_mod); kfree(tmp_options); return ret; }
