CVE-2026-72257

In the Linux kernel, the following vulnerability has been resolved:

ASoC: qcom: q6apm: fix NULL pointer dereference in graph_callback

When q6apm_free_fragments() is called it frees rx_data.buf/tx_data.buf

and sets them to NULL under graph->lock. A late DSP buffer-done response

can race with this: graph_callback() passes the !graph->ar_graph guard

(not yet NULL), acquires the lock, but then dereferences a now-NULL buf

pointer to read buf[token].phys, crashing at virtual address 0x10.

Add a NULL check for buf inside the mutex-protected section in both the

write-done (DATA_CMD_RSP_WR_SH_MEM_EP_DATA_BUFFER_DONE_V2) and

read-done (DATA_CMD_RSP_RD_SH_MEM_EP_DATA_BUFFER_V2) handlers and bail

out cleanly if buffers have already been freed.

This problem is only shown up recently while apr bus was updated to

process the commands per service rather from single global queue.