On 5/18/2016 3:36 PM, Rob Herring wrote:
> On Wed, May 18, 2016 at 10:34 AM, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote:
>> Hi Rhyland,
>>
>> I'm seeing a crash on boot that seems to have been caused by
>> "drivers/of: Fix depth when unflattening devicetree":
>>
>> [ 61.145229] ==================================================================
>>
>> [ 61.147588] BUG: KASAN: stack-out-of-bounds in unflatten_dt_nodes+0x11d2/0x1290 at addr ffff88005b30777c
>
> The following appears to fix it for me. Rhyland, please confirm.
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 7f38241..888ec2a 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -409,7 +409,7 @@ static int unflatten_dt_nodes(const void *blob,
> fpsizes[depth] = dad ? strlen(of_node_full_name(dad)) : 0;
> nps[depth+1] = dad;
> for (offset = 0;
> - offset >= 0;
> + offset >= 0, depth >= 0;
> offset = fdt_next_node(blob, offset, &depth)) {
> if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH))
> continue;
>
If I try that patch, i see this when compiling:
In function ‘unflatten_dt_nodes’:
warning: left-hand operand of comma expression has no effect
[-Wunused-value]
offset >= 0, depth >= 0;
And if I boot it, then I hit a NULL pointer dereference:
[ 0.000000] Unable to handle kernel NULL pointer dereference at
virtual address 00000058
[ 0.000000] pgd = ffff000008cb4000
[ 0.000000] [00000058] *pgd=000000013fffe003, *pud=000000013fffd003,
*pmd=0000000000000000
[ 0.000000] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted
4.6.0-next-20160518+ #26
[ 0.000000] Hardware name: Google Pixel C (DT)
[ 0.000000] task: ffff000008bdd880 ti: ffff000008bd0000 task.ti:
ffff000008bd0000
[ 0.000000] PC is at unflatten_dt_nodes+0x430/0x598
[ 0.000000] LR is at unflatten_dt_nodes+0x41c/0x598
[ 0.000000] pc : [<ffff0000086633dc>] lr : [<ffff0000086633c8>]
pstate: 800002c5
If I run this on my board, I see unflatten_dt_nodes return from inside
the loop after "populate_node" when called with depth = -1 (returning
mem-base) rather than breaking out of the loop and continuing.
-rhyland
--
nvpublic
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
