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Date: Thu, 2 Mar 2017 12:43:14 +0200
From: Elena Reshetova <elena.reshetova@...el.com>
To: linux-kernel@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, linux-nilfs@...r.kernel.org,
linux-cachefs@...hat.com, linux-cifs@...r.kernel.org,
peterz@...radead.org, gregkh@...uxfoundation.org,
viro@...iv.linux.org.uk, dhowells@...hat.com, sfrench@...ba.org,
eparis@...isplace.org, konishi.ryusuke@....ntt.co.jp,
john@...nmccutchan.com, rlove@...ve.org, paul@...l-moore.com,
Elena Reshetova <elena.reshetova@...el.com>,
Hans Liljestrand <ishkamiel@...il.com>,
Kees Cook <keescook@...omium.org>,
David Windsor <dwindsor@...il.com>
Subject: [PATCH 07/10] fs, fscache: convert fscache_operation.usage from atomic_t to refcount_t
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@...el.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: David Windsor <dwindsor@...il.com>
---
fs/cachefiles/rdwr.c | 2 +-
fs/fscache/operation.c | 38 +++++++++++++++++++-------------------
fs/fscache/page.c | 2 +-
include/linux/fscache-cache.h | 4 ++--
4 files changed, 23 insertions(+), 23 deletions(-)
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index afbdc41..c987de6 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -692,7 +692,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
struct cachefiles_cache, cache);
_enter("{OBJ%x,%d},,%d,,",
- object->fscache.debug_id, atomic_read(&op->op.usage),
+ object->fscache.debug_id, refcount_read(&op->op.usage),
*nr_pages);
if (!object->backer)
diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c
index de67745..eb84c95 100644
--- a/fs/fscache/operation.c
+++ b/fs/fscache/operation.c
@@ -38,7 +38,7 @@ void fscache_operation_init(struct fscache_operation *op,
fscache_operation_release_t release)
{
INIT_WORK(&op->work, fscache_op_work_func);
- atomic_set(&op->usage, 1);
+ refcount_set(&op->usage, 1);
op->state = FSCACHE_OP_ST_INITIALISED;
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
op->processor = processor;
@@ -60,19 +60,19 @@ EXPORT_SYMBOL(fscache_operation_init);
void fscache_enqueue_operation(struct fscache_operation *op)
{
_enter("{OBJ%x OP%x,%u}",
- op->object->debug_id, op->debug_id, atomic_read(&op->usage));
+ op->object->debug_id, op->debug_id, refcount_read(&op->usage));
ASSERT(list_empty(&op->pend_link));
ASSERT(op->processor != NULL);
ASSERT(fscache_object_is_available(op->object));
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
fscache_stat(&fscache_n_op_enqueue);
switch (op->flags & FSCACHE_OP_TYPE) {
case FSCACHE_OP_ASYNC:
_debug("queue async");
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
if (!queue_work(fscache_op_wq, &op->work))
fscache_put_operation(op);
break;
@@ -156,7 +156,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
@@ -183,11 +183,11 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
object->n_exclusive++; /* reads and writes must wait */
if (object->n_in_progress > 0) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
@@ -203,7 +203,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
op->object = object;
object->n_ops++;
object->n_exclusive++; /* reads and writes must wait */
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
@@ -238,10 +238,10 @@ int fscache_submit_op(struct fscache_object *object,
int ret;
_enter("{OBJ%x OP%x},{%u}",
- object->debug_id, op->debug_id, atomic_read(&op->usage));
+ object->debug_id, op->debug_id, refcount_read(&op->usage));
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
@@ -267,11 +267,11 @@ int fscache_submit_op(struct fscache_object *object,
object->n_ops++;
if (object->n_exclusive > 0) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
@@ -283,7 +283,7 @@ int fscache_submit_op(struct fscache_object *object,
} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
op->object = object;
object->n_ops++;
- atomic_inc(&op->usage);
+ refcount_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
@@ -359,7 +359,7 @@ int fscache_cancel_op(struct fscache_operation *op,
ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
spin_lock(&object->lock);
@@ -481,11 +481,11 @@ void fscache_put_operation(struct fscache_operation *op)
struct fscache_cache *cache;
_enter("{OBJ%x OP%x,%d}",
- op->object->debug_id, op->debug_id, atomic_read(&op->usage));
+ op->object->debug_id, op->debug_id, refcount_read(&op->usage));
- ASSERTCMP(atomic_read(&op->usage), >, 0);
+ ASSERTCMP(refcount_read(&op->usage), >, 0);
- if (!atomic_dec_and_test(&op->usage))
+ if (!refcount_dec_and_test(&op->usage))
return;
_debug("PUT OP");
@@ -569,7 +569,7 @@ void fscache_operation_gc(struct work_struct *work)
object->debug_id, op->debug_id);
fscache_stat(&fscache_n_op_gc);
- ASSERTCMP(atomic_read(&op->usage), ==, 0);
+ ASSERTCMP(refcount_read(&op->usage), ==, 0);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
ASSERTCMP(object->n_ops, >, 0);
@@ -599,7 +599,7 @@ void fscache_op_work_func(struct work_struct *work)
unsigned long start;
_enter("{OBJ%x OP%x,%d}",
- op->object->debug_id, op->debug_id, atomic_read(&op->usage));
+ op->object->debug_id, op->debug_id, refcount_read(&op->usage));
ASSERT(op->processor != NULL);
start = jiffies;
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index c8c4f79..352393c 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -774,7 +774,7 @@ static void fscache_write_op(struct fscache_operation *_op)
void *results[1];
int ret;
- _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
+ _enter("{OP%x,%d}", op->op.debug_id, refcount_read(&op->op.usage));
spin_lock(&object->lock);
cookie = object->cookie;
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index dcec7b3..0093158 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -103,7 +103,7 @@ struct fscache_operation {
#define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */
enum fscache_operation_state state;
- atomic_t usage;
+ refcount_t usage;
unsigned debug_id; /* debugging ID */
/* operation processor callback
@@ -161,7 +161,7 @@ typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op,
static inline
struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op)
{
- atomic_inc(&op->op.usage);
+ refcount_inc(&op->op.usage);
return op;
}
--
2.7.4
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