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debug: debug_stream: validate record size once and for write #11366

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Merged
lgirdwood merged 1 commit into from
Oct 28, 2026
Merged

debug: debug_stream: validate record size once and for write #11366

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35 changes: 26 additions & 9 deletions src/debug/debug_stream/debug_stream_slot.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@

#ifdef CONFIG_USERSPACE
#include <zephyr/internal/syscall_handler.h>
#include <zephyr/sys/math_extras.h>
#endif

LOG_MODULE_REGISTER(debug_stream_slot);
Expand Down Expand Up @@ -70,22 +71,26 @@ debug_stream_get_circular_buffer(struct debug_stream_section_descriptor *desc, u
return (struct debug_stream_circular_buf *) (((uint8_t *)hdr) + desc->offset);
}

int z_impl_debug_stream_slot_send_record(struct debug_stream_record *rec)
/*
* @record_size is the record length in words. It is passed separately and
* rec->size_words must not be re-read here: the system call validator
* checked access to exactly @record_size words of user memory.
*/
static int debug_stream_slot_send_sized(struct debug_stream_record *rec, uint32_t record_size)
{
struct debug_stream_section_descriptor desc = { 0 };
struct debug_stream_circular_buf *buf =
debug_stream_get_circular_buffer(&desc, arch_proc_id());
uint32_t record_size = rec->size_words;
uint32_t record_start, buf_remain;
k_spinlock_key_t key;

LOG_DBG("Sending record %u id %u len %u", rec->seqno, rec->id, rec->size_words);
LOG_DBG("Sending record len %u", record_size);

if (!buf)
return -ENODEV;

if (rec->size_words >= desc.buf_words) {
LOG_ERR("Record too big %u >= %u (desc %u %u %u)", rec->size_words,
if (record_size >= desc.buf_words) {
LOG_ERR("Record too big %u >= %u (desc %u %u %u)", record_size,
desc.buf_words, desc.core_id, desc.buf_words, desc.offset);
return -ENOMEM;
}
Expand Down Expand Up @@ -119,16 +124,28 @@ int z_impl_debug_stream_slot_send_record(struct debug_stream_record *rec)

k_spin_unlock(&cpu_mutex[arch_proc_id()].l, key);

LOG_DBG("Record %u id %u len %u sent", rec->seqno, rec->id, record_size);
LOG_DBG("Record len %u sent", record_size);
return 0;
}

int z_impl_debug_stream_slot_send_record(struct debug_stream_record *rec)
{
return debug_stream_slot_send_sized(rec, rec->size_words);
}

#ifdef CONFIG_USERSPACE
static inline int z_vrfy_debug_stream_slot_send_record(struct debug_stream_record *rec)
{
K_OOPS(K_SYSCALL_MEMORY_READ(rec, sizeof(*rec)));
K_OOPS(K_SYSCALL_MEMORY_READ(rec, rec->size_words * sizeof(uint32_t)));
return z_impl_debug_stream_slot_send_record(rec);
uint32_t size_words;
size_t bytes;

/* the impl writes seqno and size_words back to the record */
K_OOPS(K_SYSCALL_MEMORY_WRITE(rec, sizeof(*rec)));
K_OOPS(k_usermode_from_copy(&size_words, &rec->size_words, sizeof(size_words)));
K_OOPS(size_mul_overflow(size_words, sizeof(uint32_t), &bytes));
K_OOPS(K_SYSCALL_MEMORY_READ(rec, MAX(bytes, sizeof(*rec))));

return debug_stream_slot_send_sized(rec, size_words);
}
#include <zephyr/syscalls/debug_stream_slot_send_record_mrsh.c>
#endif
Expand Down
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