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SubjectRe: [BUG]: mm/vmalloc: uninitialized variable access in pcpu_get_vm_areas
On 2019-06-17 16:44, Arnd Bergmann wrote:
> On Mon, Jun 17, 2019 at 4:12 PM Uladzislau Rezki <urezki@gmail.com>
> wrote:
>>
>> On Mon, Jun 17, 2019 at 02:14:11PM +0200, Arnd Bergmann wrote:
>> > gcc points out some obviously broken code in linux-next
>> >
>> > mm/vmalloc.c: In function 'pcpu_get_vm_areas':
>> > mm/vmalloc.c:991:4: error: 'lva' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>> > insert_vmap_area_augment(lva, &va->rb_node,
>> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > &free_vmap_area_root, &free_vmap_area_list);
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > mm/vmalloc.c:916:20: note: 'lva' was declared here
>> > struct vmap_area *lva;
>> > ^~~
>> >
>> > Remove the obviously broken code. This is almost certainly
>> > not the correct solution, but it's what I have applied locally
>> > to get a clean build again.
>> >
>> > Please fix this properly.
>> >
>
>> >
>> Please do not apply this. It will just break everything.
>
> As I wrote in my description, this was purely meant as a bug
> report, not a patch to be applied.

That's a perfect way to attract attention! :)

>
>> As Roman pointed we can just set lva = NULL; in the beginning to make
>> GCC happy.
>> For some reason GCC decides that it can be used uninitialized, but
>> that
>> is not true.
>
> I got confused by the similarly named FL_FIT_TYPE/NE_FIT_TYPE

Names are indeed very confusing, that is true. Very easy to mix up
things.

--
Roman

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