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| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:38 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-11-17 21:48:01 +0300 |
| commit | 212bf41d88c06afc23e03f9b274eebf1e8dba197 (patch) | |
| tree | 755a58e9b423e6e8bfe06fa2036b633a427ff42b /include/linux/nfs_fs_sb.h | |
| parent | 2f62b5aa4814be2c511553fd6afb4d35b6c2503b (diff) | |
| download | linux-212bf41d88c06afc23e03f9b274eebf1e8dba197.tar.xz | |
fs, nfs: convert nfs_client.cl_count from atomic_t to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable nfs_client.cl_count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'include/linux/nfs_fs_sb.h')
| -rw-r--r-- | include/linux/nfs_fs_sb.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h index 74c44665e6d3..efcfe9ded9ea 100644 --- a/include/linux/nfs_fs_sb.h +++ b/include/linux/nfs_fs_sb.h @@ -9,6 +9,7 @@ #include <linux/sunrpc/xprt.h> #include <linux/atomic.h> +#include <linux/refcount.h> struct nfs4_session; struct nfs_iostats; @@ -24,7 +25,7 @@ struct nfs41_impl_id; * The nfs_client identifies our client state to the server. */ struct nfs_client { - atomic_t cl_count; + refcount_t cl_count; atomic_t cl_mds_count; int cl_cons_state; /* current construction state (-ve: init error) */ #define NFS_CS_READY 0 /* ready to be used */ |