From: Alexander Shishkin alexander.shishkin@linux.intel.com
commit e78e1fdb282726beaf88aa75943682217e6ded0e upstream.
Connecting master to an output port when GTH driver module is not loaded triggers a NULL dereference:
RIP: 0010:intel_th_set_output+0x35/0x70 [intel_th] Call Trace: ? sth_stm_link+0x12/0x20 [intel_th_sth] stm_source_link_store+0x164/0x270 [stm_core] dev_attr_store+0x17/0x30 sysfs_kf_write+0x3e/0x50 kernfs_fop_write+0xda/0x1b0 __vfs_write+0x1b/0x40 vfs_write+0xb9/0x1a0 ksys_write+0x67/0xe0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x57/0x1d0 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Make sure the module in question is loaded and return an error if not.
Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com Fixes: 39f4034693b7c ("intel_th: Add driver infrastructure for Intel(R) Trace Hub devices") Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Reported-by: Ammy Yi ammy.yi@intel.com Tested-by: Ammy Yi ammy.yi@intel.com Cc: stable@vger.kernel.org # v4.4 Link: https://lore.kernel.org/r/20200706161339.55468-5-alexander.shishkin@linux.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/hwtracing/intel_th/core.c | 21 ++++++++++++++++++--- drivers/hwtracing/intel_th/sth.c | 4 +--- 2 files changed, 19 insertions(+), 6 deletions(-)
--- a/drivers/hwtracing/intel_th/core.c +++ b/drivers/hwtracing/intel_th/core.c @@ -944,15 +944,30 @@ int intel_th_set_output(struct intel_th_ { struct intel_th_device *hub = to_intel_th_hub(thdev); struct intel_th_driver *hubdrv = to_intel_th_driver(hub->dev.driver); + int ret;
/* In host mode, this is up to the external debugger, do nothing. */ if (hub->host_mode) return 0;
- if (!hubdrv->set_output) - return -ENOTSUPP; + /* + * hub is instantiated together with the source device that + * calls here, so guaranteed to be present. + */ + hubdrv = to_intel_th_driver(hub->dev.driver); + if (!hubdrv || !try_module_get(hubdrv->driver.owner)) + return -EINVAL;
- return hubdrv->set_output(hub, master); + if (!hubdrv->set_output) { + ret = -ENOTSUPP; + goto out; + } + + ret = hubdrv->set_output(hub, master); + +out: + module_put(hubdrv->driver.owner); + return ret; } EXPORT_SYMBOL_GPL(intel_th_set_output);
--- a/drivers/hwtracing/intel_th/sth.c +++ b/drivers/hwtracing/intel_th/sth.c @@ -157,9 +157,7 @@ static int sth_stm_link(struct stm_data { struct sth_device *sth = container_of(stm_data, struct sth_device, stm);
- intel_th_set_output(to_intel_th_device(sth->dev), master); - - return 0; + return intel_th_set_output(to_intel_th_device(sth->dev), master); }
static int intel_th_sw_init(struct sth_device *sth)