* Re: drm/nouveau: do not allow negative sizes for now
[not found] <20130723230814.C82D766092E@gitolite.kernel.org>
@ 2013-07-30 0:21 ` Dave Jones
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From: Dave Jones @ 2013-07-30 0:21 UTC (permalink / raw)
To: Linux Kernel Mailing List; +Cc: maarten.lankhorst, bskeggs
On Tue, Jul 23, 2013 at 11:08:14PM +0000, Linux Kernel wrote:
> Gitweb: http://git.kernel.org/linus/;a=commit;h=0108bc808107b97e101b15af9705729626be6447
> Commit: 0108bc808107b97e101b15af9705729626be6447
> Author: Maarten Lankhorst <maarten.lankhorst@canonical.com>
> AuthorDate: Sun Jul 7 10:40:19 2013 +0200
> Committer: Ben Skeggs <bskeggs@redhat.com>
> CommitDate: Wed Jul 10 10:48:07 2013 +1000
>
> drm/nouveau: do not allow negative sizes for now
>
> The API allows up to 64-bits allocations, but size is handled as int
> inside nouveau almost everywhere. Until this is fixed it's better to
> prevent negative sizes.
>
> The 256 kB before INT_MAX is paranoia, because of the large page
> aligning below that could flip it above INT_MAX.
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
> index 459a445..4e7ee5f 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
> @@ -198,6 +198,12 @@ nouveau_bo_new(struct drm_device *dev, int size, int align,
> size_t acc_size;
> int ret;
> int type = ttm_bo_type_device;
> + int max_size = INT_MAX & ~((1 << drm->client.base.vm->vmm->lpg_shift) - 1);
> +
> + if (size <= 0 || size > max_size) {
> + nv_warn(drm, "skipped size %x\n", (u32)size);
> + return -EINVAL;
> + }
>
> if (sg)
> type = ttm_bo_type_sg;
A few more lines down..
222 if (drm->client.base.vm) {
223 if (!(flags & TTM_PL_FLAG_TT) && size > 256 * 1024)
Which implies we may now be dereferencing NULL in some situations.
Either the check needs moving higher, or removing.
Can we get here with a NULL client.base.vm ?
Dave
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