2019-08-20 07:55:32

by Wenwen Wang

Subject: [PATCH] NFSv4: Fix a memory leak bug

In nfs4_try_migration(), if nfs4_begin_drain_session() fails, the
previously allocated 'page' and 'locations' are not deallocated, leading to
memory leaks. To fix this issue, free 'page' and 'locations' before
returning the error.

Signed-off-by: Wenwen Wang <[email protected]>
---
fs/nfs/nfs4state.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index cad4e06..37823dc 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2095,8 +2095,12 @@ static int nfs4_try_migration(struct nfs_server *server, const struct cred *cred
}

status = nfs4_begin_drain_session(clp);
- if (status != 0)
+ if (status != 0) {
+ if (page != NULL)
+ __free_page(page);
+ kfree(locations);
return status;
+ }

status = nfs4_replace_transport(server, locations);
if (status != 0) {
--
2.7.4

2019-08-20 13:44:12

by Anna Schumaker

Subject: Re: [PATCH] NFSv4: Fix a memory leak bug

Hi Wenwen,

On Tue, 2019-08-20 at 02:54 -0500, Wenwen Wang wrote:
> In nfs4_try_migration(), if nfs4_begin_drain_session() fails, the
> previously allocated 'page' and 'locations' are not deallocated,
> leading to
> memory leaks. To fix this issue, free 'page' and 'locations' before
> returning the error.
>
> Signed-off-by: Wenwen Wang <[email protected]>
> ---
> fs/nfs/nfs4state.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> index cad4e06..37823dc 100644
> --- a/fs/nfs/nfs4state.c
> +++ b/fs/nfs/nfs4state.c
> @@ -2095,8 +2095,12 @@ static int nfs4_try_migration(struct
> nfs_server *server, const struct cred *cred
> }
>
> status = nfs4_begin_drain_session(clp);
> - if (status != 0)
> + if (status != 0) {
> + if (page != NULL)
> + __free_page(page);
> + kfree(locations);
> return status;

Thanks for the suggestion! I think a better option would be to switch
the "return status" into a "goto out" so we can keep all our cleanup
code in a single place in case we ever need to change it in the future.

What do you think?
Anna

> + }
>
> status = nfs4_replace_transport(server, locations);
> if (status != 0) {
> --
> 2.7.4
>