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authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 12:53:29 +0300
committerJ. Bruce Fields <bfields@redhat.com>2017-11-08 00:43:59 +0300
commitcff7cb2ece397760195ff8a5fc6bf3c860810246 (patch)
tree7d253b4fc7b44d2f1b2f0e9aa7715fad8479ae0e /fs/nfsd/state.h
parenta15dfcd529ab43265e70ec32d3b9d2286872d412 (diff)
downloadlinux-cff7cb2ece397760195ff8a5fc6bf3c860810246.tar.xz
fs, nfsd: convert nfs4_cntl_odstate.co_odcount 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_cntl_odstate.co_odcount 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: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd/state.h')
-rw-r--r--fs/nfsd/state.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index c259271c35a4..2ed368a91a10 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -468,7 +468,7 @@ struct nfs4_clnt_odstate {
struct nfs4_client *co_client;
struct nfs4_file *co_file;
struct list_head co_perfile;
- atomic_t co_odcount;
+ refcount_t co_odcount;
};
/*