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drivers, net, mlx4: convert mlx4_cq.refcount from atomic_t to refcount_t

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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 mlx4_cq.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: David S. Miller <davem@davemloft.net>
This commit is contained in:
Elena Reshetova 2017-10-20 10:23:37 +03:00 committed by David S. Miller
parent c6d4e63e06
commit ff61b5e3f0
2 changed files with 6 additions and 6 deletions
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8
drivers/net/ethernet/mellanox/mlx4/cq.c
View File

@ -69,7 +69,7 @@ void mlx4_cq_tasklet_cb(unsigned long data)
list_for_each_entry_safe(mcq, temp, &ctx->process_list, tasklet_ctx.list) {
list_del_init(&mcq->tasklet_ctx.list);
mcq->tasklet_ctx.comp(mcq);
if (atomic_dec_and_test(&mcq->refcount))
if (refcount_dec_and_test(&mcq->refcount))
complete(&mcq->free);
if (time_after(jiffies, end))
break;
@ -92,7 +92,7 @@ static void mlx4_add_cq_to_tasklet(struct mlx4_cq *cq)
* still arrive.
*/
if (list_empty_careful(&cq->tasklet_ctx.list)) {
atomic_inc(&cq->refcount);
refcount_inc(&cq->refcount);
kick = list_empty(&tasklet_ctx->list);
list_add_tail(&cq->tasklet_ctx.list, &tasklet_ctx->list);
if (kick)
@ -344,7 +344,7 @@ int mlx4_cq_alloc(struct mlx4_dev *dev, int nent,
cq->cons_index = 0;
cq->arm_sn = 1;
cq->uar = uar;
atomic_set(&cq->refcount, 1);
refcount_set(&cq->refcount, 1);
init_completion(&cq->free);
cq->comp = mlx4_add_cq_to_tasklet;
cq->tasklet_ctx.priv =
@ -386,7 +386,7 @@ void mlx4_cq_free(struct mlx4_dev *dev, struct mlx4_cq *cq)
priv->eq_table.eq[MLX4_EQ_ASYNC].irq)
synchronize_irq(priv->eq_table.eq[MLX4_EQ_ASYNC].irq);
if (atomic_dec_and_test(&cq->refcount))
if (refcount_dec_and_test(&cq->refcount))
complete(&cq->free);
wait_for_completion(&cq->free);

4
include/linux/mlx4/device.h
View File

@ -40,7 +40,7 @@
#include <linux/cpu_rmap.h>
#include <linux/crash_dump.h>
#include <linux/atomic.h>
#include <linux/refcount.h>
#include <linux/timecounter.h>
@ -751,7 +751,7 @@ struct mlx4_cq {
int cqn;
unsigned vector;
atomic_t refcount;
refcount_t refcount;
struct completion free;
struct {
struct list_head list;