diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2016-01-13 14:07:25 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-03-03 15:07:11 -0800 |
commit | 827685a637e0074e0d61d84eac4a50481c7e1b61 (patch) | |
tree | 6ebdaded1aab0b4805f15faecd103105ffe28824 /drivers/parisc | |
parent | 18b75e0bdc6c1413a44db3d37b6d1d82d02eb84b (diff) |
genirq: Validate action before dereferencing it in handle_irq_event_percpu()
commit 570540d50710ed192e98e2f7f74578c9486b6b05 upstream.
commit 71f64340fc0e changed the handling of irq_desc->action from
CPU 0 CPU 1
free_irq() lock(desc)
lock(desc) handle_edge_irq()
if (desc->action) {
handle_irq_event()
action = desc->action
unlock(desc)
desc->action = NULL handle_irq_event_percpu(desc, action)
action->xxx
to
CPU 0 CPU 1
free_irq() lock(desc)
lock(desc) handle_edge_irq()
if (desc->action) {
handle_irq_event()
unlock(desc)
desc->action = NULL handle_irq_event_percpu(desc, action)
action = desc->action
action->xxx
So if free_irq manages to set the action to NULL between the unlock and before
the readout, we happily dereference a null pointer.
We could simply revert 71f64340fc0e, but we want to preserve the better code
generation. A simple solution is to change the action loop from a do {} while
to a while {} loop.
This is safe because we either see a valid desc->action or NULL. If the action
is about to be removed it is still valid as free_irq() is blocked on
synchronize_irq().
CPU 0 CPU 1
free_irq() lock(desc)
lock(desc) handle_edge_irq()
handle_irq_event(desc)
set(INPROGRESS)
unlock(desc)
handle_irq_event_percpu(desc)
action = desc->action
desc->action = NULL while (action) {
action->xxx
...
action = action->next;
sychronize_irq()
while(INPROGRESS); lock(desc)
clr(INPROGRESS)
free(action)
That's basically the same mechanism as we have for shared
interrupts. action->next can become NULL while handle_irq_event_percpu()
runs. Either it sees the action or NULL. It does not matter, because action
itself cannot go away before the interrupt in progress flag has been cleared.
Fixes: commit 71f64340fc0e "genirq: Remove the second parameter from handle_irq_event_percpu()"
Reported-by: zyjzyj2000@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Huang Shijie <shijie.huang@arm.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1601131224190.3575@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/parisc')
0 files changed, 0 insertions, 0 deletions