* [PATCH] nvmem: core: fix error path in nvmem_add_cells()
@ 2016-02-08 21:04 Rasmus Villemoes
2016-02-17 10:48 ` Srinivas Kandagatla
0 siblings, 1 reply; 4+ messages in thread
From: Rasmus Villemoes @ 2016-02-08 21:04 UTC (permalink / raw)
To: Srinivas Kandagatla, Maxime Ripard
Cc: Greg Kroah-Hartman, Rasmus Villemoes, linux-kernel
The current code fails to nvmem_cell_drop(cells[0]) - even worse, if
the loop above fails already at i==0, we'll enter an essentially
infinite loop doing nvmem_cell_drop on cells[-1], cells[-2], ... which
is unlikely to end well.
Also, we're not freeing the temporary backing array cells on the error
path.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
drivers/nvmem/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 6fd4e5a5ef4a..1e65eccfea83 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -288,9 +288,11 @@ static int nvmem_add_cells(struct nvmem_device *nvmem,
return 0;
err:
- while (--i)
+ while (i--)
nvmem_cell_drop(cells[i]);
+ kfree(cells);
+
return rval;
}
--
2.1.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] nvmem: core: fix error path in nvmem_add_cells()
2016-02-08 21:04 [PATCH] nvmem: core: fix error path in nvmem_add_cells() Rasmus Villemoes
@ 2016-02-17 10:48 ` Srinivas Kandagatla
2016-02-18 5:35 ` Rasmus Villemoes
0 siblings, 1 reply; 4+ messages in thread
From: Srinivas Kandagatla @ 2016-02-17 10:48 UTC (permalink / raw)
To: Rasmus Villemoes, Maxime Ripard; +Cc: Greg Kroah-Hartman, linux-kernel
Hi Rasmus,
Thanks for the patch,
On 08/02/16 21:04, Rasmus Villemoes wrote:
> The current code fails to nvmem_cell_drop(cells[0]) - even worse, if
> the loop above fails already at i==0, we'll enter an essentially
> infinite loop doing nvmem_cell_drop on cells[-1], cells[-2], ... which
> is unlikely to end well.
I agree, it would fail in case of zero.
>
> Also, we're not freeing the temporary backing array cells on the error
> path.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> drivers/nvmem/core.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 6fd4e5a5ef4a..1e65eccfea83 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -288,9 +288,11 @@ static int nvmem_add_cells(struct nvmem_device *nvmem,
>
> return 0;
> err:
> - while (--i)
> + while (i--)
> nvmem_cell_drop(cells[i]);
No, this will not work.
3 issues,
1> If we enter this err path from nvmem_cell_info_to_nvmem_cell()
failures, you would be accessing already freed cells[i].
2> accessing un-allocated cells[i].
3> you would be trying to drop cells which are not in the list.
This is what you need here to fix it correctly.
while (--i >= 0)
>
> + kfree(cells);
This change looks good.
> +
> return rval;
> }
>
>
--srini
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] nvmem: core: fix error path in nvmem_add_cells()
2016-02-17 10:48 ` Srinivas Kandagatla
@ 2016-02-18 5:35 ` Rasmus Villemoes
2016-02-18 9:07 ` Srinivas Kandagatla
0 siblings, 1 reply; 4+ messages in thread
From: Rasmus Villemoes @ 2016-02-18 5:35 UTC (permalink / raw)
To: Srinivas Kandagatla; +Cc: Maxime Ripard, Greg Kroah-Hartman, linux-kernel
On Wed, Feb 17 2016, Srinivas Kandagatla <srinivas.kandagatla@linaro.org> wrote:
>> err:
>> - while (--i)
>> + while (i--)
>> nvmem_cell_drop(cells[i]);
> No, this will not work.
>
> 3 issues,
>
> 1> If we enter this err path from nvmem_cell_info_to_nvmem_cell()
> failures, you would be accessing already freed cells[i].
>
> 2> accessing un-allocated cells[i].
>
> 3> you would be trying to drop cells which are not in the list.
>
>
> This is what you need here to fix it correctly.
>
> while (--i >= 0)
>
Sigh. http://thread.gmane.org/gmane.linux.kernel.mm/146058/focus=2149595
TL;DR: They're equivalent.
Rasmus
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] nvmem: core: fix error path in nvmem_add_cells()
2016-02-18 5:35 ` Rasmus Villemoes
@ 2016-02-18 9:07 ` Srinivas Kandagatla
0 siblings, 0 replies; 4+ messages in thread
From: Srinivas Kandagatla @ 2016-02-18 9:07 UTC (permalink / raw)
To: Rasmus Villemoes; +Cc: Maxime Ripard, Greg Kroah-Hartman, linux-kernel
On 18/02/16 05:35, Rasmus Villemoes wrote:
> On Wed, Feb 17 2016, Srinivas Kandagatla <srinivas.kandagatla@linaro.org> wrote:
>
>>> err:
>>> - while (--i)
>>> + while (i--)
>> This is what you need here to fix it correctly.
>>
>> while (--i >= 0)
>>
>
> Sigh. http://thread.gmane.org/gmane.linux.kernel.mm/146058/focus=2149595
Yes, You are correct! :-)
I will queue this patch.
--srini
>
> TL;DR: They're equivalent.
>
> Rasmus
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-02-18 9:07 UTC | newest]
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2016-02-08 21:04 [PATCH] nvmem: core: fix error path in nvmem_add_cells() Rasmus Villemoes
2016-02-17 10:48 ` Srinivas Kandagatla
2016-02-18 5:35 ` Rasmus Villemoes
2016-02-18 9:07 ` Srinivas Kandagatla
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