From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Fixes: 39f4034693b7c ("intel_th: Add driver infrastructure for Intel(R) Trace Hub devices")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Reported-by: Ammy Yi <ammy.yi@xxxxxxxxx>
Tested-by: Ammy Yi <ammy.yi@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.4
Link: https://lore.kernel.org/r/20200706161339.55468-5-alexander.shishkin@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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)
