4.17-stable review patch. If anyone has any objections, please let me know.
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From: piaojun piaojun@huawei.com
[ 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/5B3F39A0.2030509@huawei.com Fixes: 9421c3e64137ec ("net/9p/client.c: fix potential refcnt problem of trans module") Signed-off-by: Jun Piao piaojun@huawei.com Reviewed-by: Yiwen Jiang jiangyiwen@huawei.com Reviewed-by: Greg Kurz groug@kaod.org Reviewed-by: Dominique Martinet dominique.martinet@cea.fr Tested-by: Dominique Martinet dominique.martinet@cea.fr Cc: Eric Van Hensbergen ericvh@gmail.com Cc: Ron Minnich rminnich@sandia.gov Cc: Latchesar Ionkov lucho@ionkov.net Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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; }