Commit bfbe5bab authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'ptr_ring-fixes' 



Michael S. Tsirkin says:

====================
ptr_ring fixes

This fixes a bunch of issues around ptr_ring use in net core.
One of these: "tap: fix use-after-free" is also needed on net,
but can't be backported cleanly.

I will post a net patch separately.

Lightly tested - Jason, could you pls confirm this
addresses the security issue you saw with ptr_ring?
Testing reports would be appreciated too.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Tested-by: default avatarJason Wang <jasowang@redhat.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
parents 7ece54a6 491847f3

drivers/net/tap.c

+0 −3
Original line number Diff line number Diff line
@@ -330,9 +330,6 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 
	if (!q)

		return RX_HANDLER_PASS;



	if (__ptr_ring_full(&q->ring))

		goto drop;



	skb_push(skb, ETH_HLEN);



	/* Apply the forward feature mask so that we perform segmentation

include/linux/ptr_ring.h

+48 −38
Original line number Diff line number Diff line
@@ -45,9 +45,10 @@ struct ptr_ring { 
};



/* Note: callers invoking this in a loop must use a compiler barrier,

 * for example cpu_relax().  If ring is ever resized, callers must hold

 * producer_lock - see e.g. ptr_ring_full.  Otherwise, if callers don't hold

 * producer_lock, the next call to __ptr_ring_produce may fail.

 * for example cpu_relax().

 *

 * NB: this is unlike __ptr_ring_empty in that callers must hold producer_lock:

 * see e.g. ptr_ring_full.

 */

static inline bool __ptr_ring_full(struct ptr_ring *r)

{
@@ -113,7 +114,7 @@ static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr) 
	/* Pairs with smp_read_barrier_depends in __ptr_ring_consume. */

	smp_wmb();



	r->queue[r->producer++] = ptr;

	WRITE_ONCE(r->queue[r->producer++], ptr);

	if (unlikely(r->producer >= r->size))

		r->producer = 0;

	return 0;
@@ -169,32 +170,36 @@ static inline int ptr_ring_produce_bh(struct ptr_ring *r, void *ptr) 
	return ret;

}



/* Note: callers invoking this in a loop must use a compiler barrier,

 * for example cpu_relax(). Callers must take consumer_lock

 * if they dereference the pointer - see e.g. PTR_RING_PEEK_CALL.

 * If ring is never resized, and if the pointer is merely

 * tested, there's no need to take the lock - see e.g.  __ptr_ring_empty.

 * However, if called outside the lock, and if some other CPU

 * consumes ring entries at the same time, the value returned

 * is not guaranteed to be correct.

 * In this case - to avoid incorrectly detecting the ring

 * as empty - the CPU consuming the ring entries is responsible

 * for either consuming all ring entries until the ring is empty,

 * or synchronizing with some other CPU and causing it to

 * execute __ptr_ring_peek and/or consume the ring enteries

 * after the synchronization point.

 */

static inline void *__ptr_ring_peek(struct ptr_ring *r)

{

	if (likely(r->size))

		return r->queue[r->consumer_head];

		return READ_ONCE(r->queue[r->consumer_head]);

	return NULL;

}



/* See __ptr_ring_peek above for locking rules. */

/*

 * Test ring empty status without taking any locks.

 *

 * NB: This is only safe to call if ring is never resized.

 *

 * However, if some other CPU consumes ring entries at the same time, the value

 * returned is not guaranteed to be correct.

 *

 * In this case - to avoid incorrectly detecting the ring

 * as empty - the CPU consuming the ring entries is responsible

 * for either consuming all ring entries until the ring is empty,

 * or synchronizing with some other CPU and causing it to

 * re-test __ptr_ring_empty and/or consume the ring enteries

 * after the synchronization point.

 *

 * Note: callers invoking this in a loop must use a compiler barrier,

 * for example cpu_relax().

 */

static inline bool __ptr_ring_empty(struct ptr_ring *r)

{

	return !__ptr_ring_peek(r);

	if (likely(r->size))

		return !r->queue[READ_ONCE(r->consumer_head)];

	return true;

}



static inline bool ptr_ring_empty(struct ptr_ring *r)
@@ -248,22 +253,28 @@ static inline void __ptr_ring_discard_one(struct ptr_ring *r) 
	/* Fundamentally, what we want to do is update consumer

	 * index and zero out the entry so producer can reuse it.

	 * Doing it naively at each consume would be as simple as:

	 *       r->queue[r->consumer++] = NULL;

	 *       if (unlikely(r->consumer >= r->size))

	 *               r->consumer = 0;

	 *       consumer = r->consumer;

	 *       r->queue[consumer++] = NULL;

	 *       if (unlikely(consumer >= r->size))

	 *               consumer = 0;

	 *       r->consumer = consumer;

	 * but that is suboptimal when the ring is full as producer is writing

	 * out new entries in the same cache line.  Defer these updates until a

	 * batch of entries has been consumed.

	 */

	int head = r->consumer_head++;

	/* Note: we must keep consumer_head valid at all times for __ptr_ring_empty

	 * to work correctly.

	 */

	int consumer_head = r->consumer_head;

	int head = consumer_head++;



	/* Once we have processed enough entries invalidate them in

	 * the ring all at once so producer can reuse their space in the ring.

	 * We also do this when we reach end of the ring - not mandatory

	 * but helps keep the implementation simple.

	 */

	if (unlikely(r->consumer_head - r->consumer_tail >= r->batch ||

		     r->consumer_head >= r->size)) {

	if (unlikely(consumer_head - r->consumer_tail >= r->batch ||

		     consumer_head >= r->size)) {

		/* Zero out entries in the reverse order: this way we touch the

		 * cache line that producer might currently be reading the last;

		 * producer won't make progress and touch other cache lines
@@ -271,12 +282,14 @@ static inline void __ptr_ring_discard_one(struct ptr_ring *r) 
		 */

		while (likely(head >= r->consumer_tail))

			r->queue[head--] = NULL;

		r->consumer_tail = r->consumer_head;

		r->consumer_tail = consumer_head;

	}

	if (unlikely(r->consumer_head >= r->size)) {

		r->consumer_head = 0;

	if (unlikely(consumer_head >= r->size)) {

		consumer_head = 0;

		r->consumer_tail = 0;

	}

	/* matching READ_ONCE in __ptr_ring_empty for lockless tests */

	WRITE_ONCE(r->consumer_head, consumer_head);

}



static inline void *__ptr_ring_consume(struct ptr_ring *r)
@@ -453,12 +466,7 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r, 


static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)

{

	/* Allocate an extra dummy element at end of ring to avoid consumer head

	 * or produce head access past the end of the array. Possible when

	 * producer/consumer operations and __ptr_ring_peek operations run in

	 * parallel.

	 */

	return kcalloc(size + 1, sizeof(void *), gfp);

	return kcalloc(size, sizeof(void *), gfp);

}



static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
@@ -532,7 +540,9 @@ static inline void ptr_ring_unconsume(struct ptr_ring *r, void **batch, int n, 
			goto done;

		}

		r->queue[head] = batch[--n];

		r->consumer_tail = r->consumer_head = head;

		r->consumer_tail = head;

		/* matching READ_ONCE in __ptr_ring_empty for lockless tests */

		WRITE_ONCE(r->consumer_head, head);

	}



done:

include/linux/skb_array.h

+1 −1
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ static inline int skb_array_produce_any(struct skb_array *a, struct sk_buff *skb 
 */

static inline bool __skb_array_empty(struct skb_array *a)

{

	return !__ptr_ring_peek(&a->ring);

	return __ptr_ring_empty(&a->ring);

}



static inline struct sk_buff *__skb_array_peek(struct skb_array *a)

tools/virtio/linux/kernel.h

+1 −1
Original line number Diff line number Diff line
@@ -118,7 +118,7 @@ static inline void free_page(unsigned long addr) 
#define dev_err(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__)

#define dev_warn(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__)



#define WARN_ON_ONCE(cond) ((cond) && fprintf (stderr, "WARNING\n"))

#define WARN_ON_ONCE(cond) ((cond) ? fprintf (stderr, "WARNING\n") : 0)



#define min(x, y) ({				\

	typeof(x) _min1 = (x);			\

tools/virtio/linux/thread_info.h

0 → 100644
+1 −0
Original line number Diff line number Diff line 
#define check_copy_size(A, B, C) (1)

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