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ptr_ring: disallow lockless __ptr_ring_full

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Similar to bcecb4bbf88a ("net: ptr_ring: otherwise safe empty checks can
overrun array bounds") a lockless use of __ptr_ring_full might
cause an out of bounds access.

We can fix this, but it's easier to just disallow lockless
__ptr_ring_full for now.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2018-01-26 01:36:32 +02:00 committed by David S. Miller
parent 88fae87327
commit 84328342a7
1 changed files with 4 additions and 3 deletions
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7
include/linux/ptr_ring.h
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@ -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)
{