From a2a5dea7b6cb77365ed9c987f54d160668c8a95f Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 20 Oct 2017 12:53:31 +0300 Subject: fs, nfs: convert nfs4_pnfs_ds.ds_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 nfs4_pnfs_ds.ds_count is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova Signed-off-by: Anna Schumaker --- fs/nfs/pnfs.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/nfs/pnfs.h') diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h index 87f144f14d1e..cefa7daf6e85 100644 --- a/fs/nfs/pnfs.h +++ b/fs/nfs/pnfs.h @@ -30,6 +30,7 @@ #ifndef FS_NFS_PNFS_H #define FS_NFS_PNFS_H +#include #include #include #include @@ -54,7 +55,7 @@ struct nfs4_pnfs_ds { char *ds_remotestr; /* comma sep list of addrs */ struct list_head ds_addrs; struct nfs_client *ds_clp; - atomic_t ds_count; + refcount_t ds_count; unsigned long ds_state; #define NFS4DS_CONNECTING 0 /* ds is establishing connection */ }; -- cgit