From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- sound/firewire/lib.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 sound/firewire/lib.c (limited to 'sound/firewire/lib.c') diff --git a/sound/firewire/lib.c b/sound/firewire/lib.c new file mode 100644 index 000000000..654e1a605 --- /dev/null +++ b/sound/firewire/lib.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * miscellaneous helper functions + * + * Copyright (c) Clemens Ladisch + */ + +#include +#include +#include +#include +#include +#include "lib.h" + +#define ERROR_RETRY_DELAY_MS 20 + +/** + * snd_fw_transaction - send a request and wait for its completion + * @unit: the driver's unit on the target device + * @tcode: the transaction code + * @offset: the address in the target's address space + * @buffer: input/output data + * @length: length of @buffer + * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the + * request only in that generation; use %FW_QUIET to suppress error + * messages + * + * Submits an asynchronous request to the target device, and waits for the + * response. The node ID and the current generation are derived from @unit. + * On a bus reset or an error, the transaction is retried a few times. + * Returns zero on success, or a negative error code. + */ +int snd_fw_transaction(struct fw_unit *unit, int tcode, + u64 offset, void *buffer, size_t length, + unsigned int flags) +{ + struct fw_device *device = fw_parent_device(unit); + int generation, rcode, tries = 0; + + generation = flags & FW_GENERATION_MASK; + for (;;) { + if (!(flags & FW_FIXED_GENERATION)) { + generation = device->generation; + smp_rmb(); /* node_id vs. generation */ + } + rcode = fw_run_transaction(device->card, tcode, + device->node_id, generation, + device->max_speed, offset, + buffer, length); + + if (rcode == RCODE_COMPLETE) + return 0; + + if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION)) + return -EAGAIN; + + if (rcode_is_permanent_error(rcode) || ++tries >= 3) { + if (!(flags & FW_QUIET)) + dev_err(&unit->device, + "transaction failed: %s\n", + fw_rcode_string(rcode)); + return -EIO; + } + + msleep(ERROR_RETRY_DELAY_MS); + } +} +EXPORT_SYMBOL(snd_fw_transaction); + +MODULE_DESCRIPTION("FireWire audio helper functions"); +MODULE_AUTHOR("Clemens Ladisch "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1