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Subject[PATCH 02/23] net, sunrpc: convert gss_cl_ctx.count from atomic_t to refcount_t
Date
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
include/linux/sunrpc/auth_gss.h | 3 ++-
net/sunrpc/auth_gss/auth_gss.c | 6 +++---
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/sunrpc/auth_gss.h b/include/linux/sunrpc/auth_gss.h
index 36eebc4..cebdf87 100644
--- a/include/linux/sunrpc/auth_gss.h
+++ b/include/linux/sunrpc/auth_gss.h
@@ -13,6 +13,7 @@
#define _LINUX_SUNRPC_AUTH_GSS_H

#ifdef __KERNEL__
+#include <linux/refcount.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/gss_api.h>
@@ -65,7 +66,7 @@ struct rpc_gss_init_res {
* the wire when communicating with a server. */

struct gss_cl_ctx {
- atomic_t count;
+ refcount_t count;
enum rpc_gss_proc gc_proc;
u32 gc_seq;
spinlock_t gc_seq_lock;
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 4f16953..72f129c 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -117,14 +117,14 @@ static const struct rpc_pipe_ops gss_upcall_ops_v1;
static inline struct gss_cl_ctx *
gss_get_ctx(struct gss_cl_ctx *ctx)
{
- atomic_inc(&ctx->count);
+ refcount_inc(&ctx->count);
return ctx;
}

static inline void
gss_put_ctx(struct gss_cl_ctx *ctx)
{
- if (atomic_dec_and_test(&ctx->count))
+ if (refcount_dec_and_test(&ctx->count))
gss_free_ctx(ctx);
}

@@ -200,7 +200,7 @@ gss_alloc_context(void)
ctx->gc_proc = RPC_GSS_PROC_DATA;
ctx->gc_seq = 1; /* NetApp 6.4R1 doesn't accept seq. no. 0 */
spin_lock_init(&ctx->gc_seq_lock);
- atomic_set(&ctx->count,1);
+ refcount_set(&ctx->count,1);
}
return ctx;
}
--
2.7.4
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