hda_generic_machine_select() appends -idisp to the tplg filename by allocating a new string with devm_kasprintf(), then stores the string right back into the global variable snd_soc_acpi_intel_hda_machines. When the module is unloaded, this memory is freed, resulting in a global variable pointing to freed memory. Reloading the module then triggers a use-after-free:
BUG: KFENCE: use-after-free read in string+0x48/0xe0
Use-after-free read at 0x00000000967e0109 (in kfence-#99): string+0x48/0xe0 vsnprintf+0x329/0x6e0 devm_kvasprintf+0x54/0xb0 devm_kasprintf+0x58/0x80 hda_machine_select.cold+0x198/0x17a2 [snd_sof_intel_hda_generic] sof_probe_work+0x7f/0x600 [snd_sof] process_one_work+0x17b/0x330 worker_thread+0x2ce/0x3f0 kthread+0xcf/0x100 ret_from_fork+0x31/0x50 ret_from_fork_asm+0x1a/0x30
kfence-#99: 0x00000000198a940f-0x00000000ace47d9d, size=64, cache=kmalloc-64
allocated by task 333 on cpu 8 at 17.798069s (130.453553s ago): devm_kmalloc+0x52/0x120 devm_kvasprintf+0x66/0xb0 devm_kasprintf+0x58/0x80 hda_machine_select.cold+0x198/0x17a2 [snd_sof_intel_hda_generic] sof_probe_work+0x7f/0x600 [snd_sof] process_one_work+0x17b/0x330 worker_thread+0x2ce/0x3f0 kthread+0xcf/0x100 ret_from_fork+0x31/0x50 ret_from_fork_asm+0x1a/0x30
freed by task 1543 on cpu 4 at 141.586686s (6.665010s ago): release_nodes+0x43/0xb0 devres_release_all+0x90/0xf0 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c1/0x200 driver_detach+0x48/0x90 bus_remove_driver+0x6d/0xf0 pci_unregister_driver+0x42/0xb0 __do_sys_delete_module+0x1d1/0x310 do_syscall_64+0x82/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Fix it by copying the match array with devm_kmemdup_array() before we modify it.
Fixes: 5458411d7594 ("ASoC: SOF: Intel: hda: refactoring topology name fixup for HDA mach") Suggested-by: Peter Ujfalusi peter.ujfalusi@linux.intel.com Acked-by: Peter Ujfalusi peter.ujfalusi@linux.intel.com Signed-off-by: Tavian Barnes tavianator@tavianator.com --- v5: Formatting fix.
v4: Copy the whole array, including the sentinel.
v3: Copy the whole machine struct instead so we can safely modify it (instead of storing the name in pdata->tplg_filename, breaking other fixups). The problem with v2 was pointed out by Bard Liao, with the alternative fix suggested by Péter Ujfalusi.
v2: Typo fix.
sound/soc/sof/intel/hda.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/sound/soc/sof/intel/hda.c b/sound/soc/sof/intel/hda.c index b34e5fdf10f1..6a3932d90b43 100644 --- a/sound/soc/sof/intel/hda.c +++ b/sound/soc/sof/intel/hda.c @@ -1049,7 +1049,21 @@ static void hda_generic_machine_select(struct snd_sof_dev *sdev, if (!*mach && codec_num <= 2) { bool tplg_fixup = false;
- hda_mach = snd_soc_acpi_intel_hda_machines; + /* + * make a local copy of the match array since we might + * be modifying it + */ + hda_mach = devm_kmemdup_array(sdev->dev, + snd_soc_acpi_intel_hda_machines, + 2, /* we have one entry + sentinel in the array */ + sizeof(snd_soc_acpi_intel_hda_machines[0]), + GFP_KERNEL); + if (!hda_mach) { + dev_err(bus->dev, + "%s: failed to duplicate the HDA match table\n", + __func__); + return; + }
dev_info(bus->dev, "using HDA machine driver %s now\n", hda_mach->drv_name);