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Tsirkin" To: Jason Wang Cc: netdev@vger.kernel.org Subject: ptr_ring_unconsume: memory corruption potential? Message-ID: <20250923235611-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Jason, guys, reading ptr ring code, I noticed: static inline void ptr_ring_unconsume(struct ptr_ring *r, void **batch, int n, void (*destroy)(void *)) { unsigned long flags; int head; spin_lock_irqsave(&r->consumer_lock, flags); spin_lock(&r->producer_lock); if (!r->size) goto done; /* * Clean out buffered entries (for simplicity). This way following code * can test entries for NULL and if not assume they are valid. */ head = r->consumer_head - 1; while (likely(head >= r->consumer_tail)) r->queue[head--] = NULL; __ptr_ring_update(r, head); r->consumer_tail = r->consumer_head; ... Does not look like this will DTRT if r->consumer_head == 0 . In fact it looks like it will go off corrupting memory. Why isn't this a concern? -- MST