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intel_th: Don't reference unassigned outputs

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When an output port driver is removed, also remove references to it from
any masters. Failing to do this causes a NULL ptr dereference when
configuring another output port:

> BUG: unable to handle kernel NULL pointer dereference at 000000000000000d
> RIP: 0010:master_attr_store+0x9d/0x160 [intel_th_gth]
> Call Trace:
> dev_attr_store+0x1b/0x30
> sysfs_kf_write+0x3c/0x50
> kernfs_fop_write+0x125/0x1a0
> __vfs_write+0x3a/0x190
> ? __vfs_write+0x5/0x190
> ? _cond_resched+0x1a/0x50
> ? rcu_all_qs+0x5/0xb0
> ? __vfs_write+0x5/0x190
> vfs_write+0xb8/0x1b0
> ksys_write+0x55/0xc0
> __x64_sys_write+0x1a/0x20
> do_syscall_64+0x5a/0x140
> entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: b27a6a3f97 ("intel_th: Add Global Trace Hub driver")
CC: stable@vger.kernel.org # v4.4+
Reported-by: Ammy Yi <ammy.yi@intel.com>
This commit is contained in:
Alexander Shishkin 2019-01-24 15:11:53 +02:00
parent 1d2ef028bf
commit 9ed3f22223
1 changed files with 4 additions and 0 deletions
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4
drivers/hwtracing/intel_th/gth.c
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@ -607,6 +607,7 @@ static void intel_th_gth_unassign(struct intel_th_device *thdev,
{
struct gth_device *gth = dev_get_drvdata(&thdev->dev);
int port = othdev->output.port;
int master;
if (thdev->host_mode)
return;
@ -615,6 +616,9 @@ static void intel_th_gth_unassign(struct intel_th_device *thdev,
othdev->output.port = -1;
othdev->output.active = false;
gth->output[port].output = NULL;
for (master = 0; master < TH_CONFIGURABLE_MASTERS; master++)
if (gth->master[master] == port)
gth->master[master] = -1;
spin_unlock(&gth->gth_lock);
}