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authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 12:53:33 +0300
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2017-11-17 13:47:59 -0500
commit2b28a7bee4539d27f4ec3b0298f03bfd83d4f794 (patch)
treeeae9a1b4816de726573ee4367dc47c9a36a1d6a3 /fs/nfs/pnfs.h
parenteba6dd691743a9d7a57735f36bf6946fc58878ec (diff)
downloadlinux-2b28a7bee4539d27f4ec3b0298f03bfd83d4f794.tar.bz2
fs, nfs: convert pnfs_layout_hdr.plh_refcount 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 pnfs_layout_hdr.plh_refcount 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 'fs/nfs/pnfs.h')
-rw-r--r--fs/nfs/pnfs.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index f0e98e1f04b2..78de7a2052f7 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -180,7 +180,7 @@ struct pnfs_layoutdriver_type {
};
struct pnfs_layout_hdr {
- atomic_t plh_refcount;
+ refcount_t plh_refcount;
atomic_t plh_outstanding; /* number of RPCs out */
struct list_head plh_layouts; /* other client layouts */
struct list_head plh_bulk_destroy;