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author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:28 +0300 |
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committer | J. Bruce Fields <bfields@redhat.com> | 2017-11-07 16:43:58 -0500 |
commit | a15dfcd529ab43265e70ec32d3b9d2286872d412 (patch) | |
tree | 798c5bbb1198cc1135fed233bc315806918cc85d /fs/nfsd/state.h | |
parent | dc3033e16c59a2c4e62b31341258a5786cbcee56 (diff) | |
download | linux-a15dfcd529ab43265e70ec32d3b9d2286872d412.tar.gz |
fs, nfsd: convert nfs4_stid.sc_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_stid.sc_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: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd/state.h')
-rw-r--r-- | fs/nfsd/state.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 86aa92d200e1..c259271c35a4 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -36,6 +36,7 @@ #define _NFSD4_STATE_H #include <linux/idr.h> +#include <linux/refcount.h> #include <linux/sunrpc/svc_xprt.h> #include "nfsfh.h" @@ -83,7 +84,7 @@ struct nfsd4_callback_ops { * fields that are of general use to any stateid. */ struct nfs4_stid { - atomic_t sc_count; + refcount_t sc_count; #define NFS4_OPEN_STID 1 #define NFS4_LOCK_STID 2 #define NFS4_DELEG_STID 4 |