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author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:29 +0300 |
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committer | J. Bruce Fields <bfields@redhat.com> | 2017-11-07 16:43:59 -0500 |
commit | cff7cb2ece397760195ff8a5fc6bf3c860810246 (patch) | |
tree | 7d253b4fc7b44d2f1b2f0e9aa7715fad8479ae0e /fs/nfsd/state.h | |
parent | a15dfcd529ab43265e70ec32d3b9d2286872d412 (diff) | |
download | linux-cff7cb2ece397760195ff8a5fc6bf3c860810246.tar.gz linux-cff7cb2ece397760195ff8a5fc6bf3c860810246.tar.bz2 linux-cff7cb2ece397760195ff8a5fc6bf3c860810246.zip |
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.h | 2 |
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; }; /* |