From 33a154a96e71a34a1bcca9f40da343dbbf7b38b4 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 1 Oct 2026 14:52:55 +0000 Subject: selftests/bpf: Test packet range of pointers sharing an id Add tests where two packet pointers share an id and tightening one pointer's umax from its var_off would put it less than their constant distance from the other's umax: with an index & 0x38 capped at 50, the base pointer keeps umax 50, so the pointer 8 bytes further on must keep umax 58, even though its known bits allow at most 56. These refused a valid program or accepted an out-of-bounds access before the fix: - check the advanced copy, load through the base: valid, was refused; - check the base, load the byte at base + 1 through a copy advanced by 8: was accepted; - check base + 4, load 4 bytes at base + 2 through base + 8: reads two bytes past the checked range, was accepted; - the same as the second with data_meta pointers checked against data: was accepted. These pass with and without the fix and cover nearby paths: - subtract an unknown scalar from a checked pointer and load below it (the range is kept across a new id); - reach a load through two paths whose checks cover 8 and 7 bytes after the loaded pointer; the second path must not be pruned by the first; - spill a copy of a pointer, check the pointer, fill the copy and load one byte past the checked range: the load is refused, and the copy has the range of the check. Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- include/drm/spsc_queue.h | 124 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 include/drm/spsc_queue.h (limited to 'include/drm/spsc_queue.h') diff --git a/include/drm/spsc_queue.h b/include/drm/spsc_queue.h new file mode 100644 index 000000000..ee9df8cc6 --- /dev/null +++ b/include/drm/spsc_queue.h @@ -0,0 +1,124 @@ +/* + * Copyright 2017 Advanced Micro Devices, Inc. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + */ + +#ifndef DRM_SCHEDULER_SPSC_QUEUE_H_ +#define DRM_SCHEDULER_SPSC_QUEUE_H_ + +#include +#include + +/** SPSC lockless queue */ + +struct spsc_node { + + /* Stores spsc_node* */ + struct spsc_node *next; +}; + +struct spsc_queue { + + struct spsc_node *head; + + /* atomic pointer to struct spsc_node* */ + atomic_long_t tail; + + atomic_t job_count; +}; + +static inline void spsc_queue_init(struct spsc_queue *queue) +{ + queue->head = NULL; + atomic_long_set(&queue->tail, (long)&queue->head); + atomic_set(&queue->job_count, 0); +} + +static inline struct spsc_node *spsc_queue_peek(struct spsc_queue *queue) +{ + return queue->head; +} + +static inline int spsc_queue_count(struct spsc_queue *queue) +{ + return atomic_read(&queue->job_count); +} + +static inline bool spsc_queue_push(struct spsc_queue *queue, struct spsc_node *node) +{ + struct spsc_node **tail; + + node->next = NULL; + + preempt_disable(); + + atomic_inc(&queue->job_count); + smp_mb__after_atomic(); + + tail = (struct spsc_node **)atomic_long_xchg(&queue->tail, (long)&node->next); + WRITE_ONCE(*tail, node); + + /* + * In case of first element verify new node will be visible to the consumer + * thread when we ping the kernel thread that there is new work to do. + */ + smp_wmb(); + + preempt_enable(); + + return tail == &queue->head; +} + + +static inline struct spsc_node *spsc_queue_pop(struct spsc_queue *queue) +{ + struct spsc_node *next, *node; + + /* Verify reading from memory and not the cache */ + smp_rmb(); + + node = READ_ONCE(queue->head); + + if (!node) + return NULL; + + next = READ_ONCE(node->next); + WRITE_ONCE(queue->head, next); + + if (unlikely(!next)) { + /* slowpath for the last element in the queue */ + + if (atomic_long_cmpxchg(&queue->tail, + (long)&node->next, (long) &queue->head) != (long)&node->next) { + /* Updating tail failed wait for new next to appear */ + do { + smp_rmb(); + } while (unlikely(!(queue->head = READ_ONCE(node->next)))); + } + } + + atomic_dec(&queue->job_count); + return node; +} + + + +#endif /* DRM_SCHEDULER_SPSC_QUEUE_H_ */ -- cgit v1.3.1