Re: [PATCH] drm/nouveau/mmu: fix Use after Free bug in nvkm_vmm_node_split
On Sat, 28 Jan 2023 03:17:15 +0100,
Danilo Krummrich wrote:
>
> On Fri, Jan 27, 2023 at 01:10:46PM +0100, Takashi Iwai wrote:
> > On Tue, 03 Jan 2023 15:07:55 +0100,
> > Takashi Iwai wrote:
> > >
> > > On Fri, 30 Dec 2022 08:27:58 +0100,
> > > Zheng Wang wrote:
> > > >
> > > > Here is a function call chain.
> > > > nvkm_vmm_pfn_map->nvkm_vmm_pfn_split_merge->nvkm_vmm_node_split
> > > > If nvkm_vma_tail return NULL in nvkm_vmm_node_split, it will
> > > > finally invoke nvkm_vmm_node_merge->nvkm_vmm_node_delete, which
> > > > will free the vma. However, nvkm_vmm_pfn_map didn't notice that.
> > > > It goes into next label and UAF happens.
> > > >
> > > > Fix it by returning the return-value of nvkm_vmm_node_merge
> > > > instead of NULL.
> > > >
> > > > Signed-off-by: Zheng Wang
> > >
> > > FWIW, CVE-2023-0030 has been assigned to this bug.
> > > It's a question whether it really deserves as a security issue, but a
> > > bug is a bug...
> > >
> > > Ben, could you review this please?
> >
> > A gentle ping as reminder. The bug is still present.
>
> This was also reported in [1]. I had a closer look and FWICT this code is fine
> and there isn't a bug.
>
> Zheng Wang, the reporter of the BZ, also confirmed this to be a false positive
> from CodeQL.
>
> Anyway, here's the explaination I also posted in the BZ:
>
> "In nvkm_vmm_node_merge() nvkm_vmm_node_delete() is only called when prev is
> set. However, prev is NULL unless we enter the "if (vma->addr != addr)" path
> in
> nvkm_vmm_node_split(). In such a case the vma pointer, which is also passed to
> nvkm_vmm_node_merge(), is set to a freshly allocated struct nvkm_vma with
> nvkm_vma_tail() right before prev is set to the old vma pointer.
>
> Hence, the only thing happening there when nvkm_vma_tail() fails in the
> "if (vma->size != size)" path is that either nvkm_vmm_node_merge() does
> nothing
> in case prev wasn't set or it merges and frees the new vma created in the
> "if (vma->addr != addr)" path. Or in other words the proper cleanup for the
> error condition is done.
>
> I can't see any case where the original vma pointer given by
> nvkm_vmm_pfn_map()
> is actually freed."
>
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=2157041
Thanks for the information! Then we should try to dispute the CVE.
I'll ask our security team.
Takashi
>
> - Danilo
>
> >
> >
> > thanks,
> >
> > Takashi
> >
> > >
> > >
> > > thanks,
> > >
> > > Takashi
> > >
> > > > ---
> > > > drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 4 ++--
> > > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > > b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > > index ae793f400ba1..84d6fc87b2e8 100644
> > > > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > > @@ -937,8 +937,8 @@ nvkm_vmm_node_split(struct nvkm_vmm *vmm,
> > > > if (vma->size != size) {
> > > > struct nvkm_vma *tmp;
> > > > if (!(tmp = nvkm_vma_tail(vma, vma->size - size))) {
> > > > - nvkm_vmm_node_merge(vmm, prev, vma, NULL,
> > > > vma->size);
> > > > - return NULL;
> > > > + tmp = nvkm_vmm_node_merge(vmm, prev, vma, NULL,
> > > > vma->size);
> > > > + return tmp;
> > > > }
> > > > tmp->part = true;
> > > > nvkm_vmm_node_insert(vmm, tmp);
> > > > --
> > > > 2.25.1
> > > >
> >
>
Re: [PATCH] drm/nouveau/mmu: fix Use after Free bug in nvkm_vmm_node_split
On Fri, Jan 27, 2023 at 01:10:46PM +0100, Takashi Iwai wrote:
> On Tue, 03 Jan 2023 15:07:55 +0100,
> Takashi Iwai wrote:
> >
> > On Fri, 30 Dec 2022 08:27:58 +0100,
> > Zheng Wang wrote:
> > >
> > > Here is a function call chain.
> > > nvkm_vmm_pfn_map->nvkm_vmm_pfn_split_merge->nvkm_vmm_node_split
> > > If nvkm_vma_tail return NULL in nvkm_vmm_node_split, it will
> > > finally invoke nvkm_vmm_node_merge->nvkm_vmm_node_delete, which
> > > will free the vma. However, nvkm_vmm_pfn_map didn't notice that.
> > > It goes into next label and UAF happens.
> > >
> > > Fix it by returning the return-value of nvkm_vmm_node_merge
> > > instead of NULL.
> > >
> > > Signed-off-by: Zheng Wang
> >
> > FWIW, CVE-2023-0030 has been assigned to this bug.
> > It's a question whether it really deserves as a security issue, but a
> > bug is a bug...
> >
> > Ben, could you review this please?
>
> A gentle ping as reminder. The bug is still present.
This was also reported in [1]. I had a closer look and FWICT this code is fine
and there isn't a bug.
Zheng Wang, the reporter of the BZ, also confirmed this to be a false positive
from CodeQL.
Anyway, here's the explaination I also posted in the BZ:
"In nvkm_vmm_node_merge() nvkm_vmm_node_delete() is only called when prev is
set. However, prev is NULL unless we enter the "if (vma->addr != addr)" path in
nvkm_vmm_node_split(). In such a case the vma pointer, which is also passed to
nvkm_vmm_node_merge(), is set to a freshly allocated struct nvkm_vma with
nvkm_vma_tail() right before prev is set to the old vma pointer.
Hence, the only thing happening there when nvkm_vma_tail() fails in the
"if (vma->size != size)" path is that either nvkm_vmm_node_merge() does nothing
in case prev wasn't set or it merges and frees the new vma created in the
"if (vma->addr != addr)" path. Or in other words the proper cleanup for the
error condition is done.
I can't see any case where the original vma pointer given by nvkm_vmm_pfn_map()
is actually freed."
[1] https://bugzilla.redhat.com/show_bug.cgi?id=2157041
- Danilo
>
>
> thanks,
>
> Takashi
>
> >
> >
> > thanks,
> >
> > Takashi
> >
> > > ---
> > > drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > index ae793f400ba1..84d6fc87b2e8 100644
> > > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > > @@ -937,8 +937,8 @@ nvkm_vmm_node_split(struct nvkm_vmm *vmm,
> > > if (vma->size != size) {
> > > struct nvkm_vma *tmp;
> > > if (!(tmp = nvkm_vma_tail(vma, vma->size - size))) {
> > > - nvkm_vmm_node_merge(vmm, prev, vma, NULL, vma->size);
> > > - return NULL;
> > > + tmp = nvkm_vmm_node_merge(vmm, prev, vma, NULL,
> > > vma->size);
> > > + return tmp;
> > > }
> > > tmp->part = true;
> > > nvkm_vmm_node_insert(vmm, tmp);
> > > --
> > > 2.25.1
> > >
>
Re: [PATCH] drm/nouveau/mmu: fix Use after Free bug in nvkm_vmm_node_split
On Tue, 03 Jan 2023 15:07:55 +0100,
Takashi Iwai wrote:
>
> On Fri, 30 Dec 2022 08:27:58 +0100,
> Zheng Wang wrote:
> >
> > Here is a function call chain.
> > nvkm_vmm_pfn_map->nvkm_vmm_pfn_split_merge->nvkm_vmm_node_split
> > If nvkm_vma_tail return NULL in nvkm_vmm_node_split, it will
> > finally invoke nvkm_vmm_node_merge->nvkm_vmm_node_delete, which
> > will free the vma. However, nvkm_vmm_pfn_map didn't notice that.
> > It goes into next label and UAF happens.
> >
> > Fix it by returning the return-value of nvkm_vmm_node_merge
> > instead of NULL.
> >
> > Signed-off-by: Zheng Wang
>
> FWIW, CVE-2023-0030 has been assigned to this bug.
> It's a question whether it really deserves as a security issue, but a
> bug is a bug...
>
> Ben, could you review this please?
A gentle ping as reminder. The bug is still present.
thanks,
Takashi
>
>
> thanks,
>
> Takashi
>
> > ---
> > drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > index ae793f400ba1..84d6fc87b2e8 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> > @@ -937,8 +937,8 @@ nvkm_vmm_node_split(struct nvkm_vmm *vmm,
> > if (vma->size != size) {
> > struct nvkm_vma *tmp;
> > if (!(tmp = nvkm_vma_tail(vma, vma->size - size))) {
> > - nvkm_vmm_node_merge(vmm, prev, vma, NULL, vma->size);
> > - return NULL;
> > + tmp = nvkm_vmm_node_merge(vmm, prev, vma, NULL,
> > vma->size);
> > + return tmp;
> > }
> > tmp->part = true;
> > nvkm_vmm_node_insert(vmm, tmp);
> > --
> > 2.25.1
> >
Re: [PATCH] drm/nouveau/mmu: fix Use after Free bug in nvkm_vmm_node_split
On Fri, 30 Dec 2022 08:27:58 +0100,
Zheng Wang wrote:
>
> Here is a function call chain.
> nvkm_vmm_pfn_map->nvkm_vmm_pfn_split_merge->nvkm_vmm_node_split
> If nvkm_vma_tail return NULL in nvkm_vmm_node_split, it will
> finally invoke nvkm_vmm_node_merge->nvkm_vmm_node_delete, which
> will free the vma. However, nvkm_vmm_pfn_map didn't notice that.
> It goes into next label and UAF happens.
>
> Fix it by returning the return-value of nvkm_vmm_node_merge
> instead of NULL.
>
> Signed-off-by: Zheng Wang
FWIW, CVE-2023-0030 has been assigned to this bug.
It's a question whether it really deserves as a security issue, but a
bug is a bug...
Ben, could you review this please?
thanks,
Takashi
> ---
> drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> index ae793f400ba1..84d6fc87b2e8 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> @@ -937,8 +937,8 @@ nvkm_vmm_node_split(struct nvkm_vmm *vmm,
> if (vma->size != size) {
> struct nvkm_vma *tmp;
> if (!(tmp = nvkm_vma_tail(vma, vma->size - size))) {
> - nvkm_vmm_node_merge(vmm, prev, vma, NULL, vma->size);
> - return NULL;
> + tmp = nvkm_vmm_node_merge(vmm, prev, vma, NULL,
> vma->size);
> + return tmp;
> }
> tmp->part = true;
> nvkm_vmm_node_insert(vmm, tmp);
> --
> 2.25.1
>
[PATCH] drm/nouveau/mmu: fix Use after Free bug in nvkm_vmm_node_split
Here is a function call chain.
nvkm_vmm_pfn_map->nvkm_vmm_pfn_split_merge->nvkm_vmm_node_split
If nvkm_vma_tail return NULL in nvkm_vmm_node_split, it will
finally invoke nvkm_vmm_node_merge->nvkm_vmm_node_delete, which
will free the vma. However, nvkm_vmm_pfn_map didn't notice that.
It goes into next label and UAF happens.
Fix it by returning the return-value of nvkm_vmm_node_merge
instead of NULL.
Signed-off-by: Zheng Wang
---
drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index ae793f400ba1..84d6fc87b2e8 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -937,8 +937,8 @@ nvkm_vmm_node_split(struct nvkm_vmm *vmm,
if (vma->size != size) {
struct nvkm_vma *tmp;
if (!(tmp = nvkm_vma_tail(vma, vma->size - size))) {
- nvkm_vmm_node_merge(vmm, prev, vma, NULL, vma->size);
- return NULL;
+ tmp = nvkm_vmm_node_merge(vmm, prev, vma, NULL,
vma->size);
+ return tmp;
}
tmp->part = true;
nvkm_vmm_node_insert(vmm, tmp);
--
2.25.1
