The code calling ima_free_kexec_buffer runs long after the memblock
allocator has already been torn down, potentially resulting in a use
after free in memblock_isolate_range.
With KASAN or KFENCE, this use after free will result in a BUG
from the idle task, and a subsequent kernel panic.
Switch ima_free_kexec_buffer over to memblock_free_late to avoid
that issue.
Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c")
Cc: [email protected]
Signed-off-by: Rik van Riel <[email protected]>
Suggested-by: Mike Rappoport <[email protected]>
---
arch/x86/kernel/setup.c | 8 ++------
drivers/of/kexec.c | 3 ++-
2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index fd975a4a5200..aa0df37c1fe7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -359,15 +359,11 @@ static void __init add_early_ima_buffer(u64 phys_addr)
#if defined(CONFIG_HAVE_IMA_KEXEC) && !defined(CONFIG_OF_FLATTREE)
int __init ima_free_kexec_buffer(void)
{
- int rc;
-
if (!ima_kexec_buffer_size)
return -ENOENT;
- rc = memblock_phys_free(ima_kexec_buffer_phys,
- ima_kexec_buffer_size);
- if (rc)
- return rc;
+ memblock_free_late(ima_kexec_buffer_phys,
+ ima_kexec_buffer_size);
ima_kexec_buffer_phys = 0;
ima_kexec_buffer_size = 0;
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index f26d2ba8a371..68278340cecf 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -184,7 +184,8 @@ int __init ima_free_kexec_buffer(void)
if (ret)
return ret;
- return memblock_phys_free(addr, size);
+ memblock_free_late(addr, size);
+ return 0;
}
#endif
--
2.41.0
On Thu, Jul 20, 2023 at 10:14:31AM -0400, Rik van Riel wrote:
> The code calling ima_free_kexec_buffer runs long after the memblock
> allocator has already been torn down, potentially resulting in a use
> after free in memblock_isolate_range.
>
> With KASAN or KFENCE, this use after free will result in a BUG
> from the idle task, and a subsequent kernel panic.
>
> Switch ima_free_kexec_buffer over to memblock_free_late to avoid
> that issue.
>
> Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c")
Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec")
Acked-by: Rob Herring <[email protected]>
(I'm assuming someone else is taking this)
> Cc: [email protected]
> Signed-off-by: Rik van Riel <[email protected]>
> Suggested-by: Mike Rappoport <[email protected]>
> ---
> arch/x86/kernel/setup.c | 8 ++------
> drivers/of/kexec.c | 3 ++-
> 2 files changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index fd975a4a5200..aa0df37c1fe7 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -359,15 +359,11 @@ static void __init add_early_ima_buffer(u64 phys_addr)
> #if defined(CONFIG_HAVE_IMA_KEXEC) && !defined(CONFIG_OF_FLATTREE)
> int __init ima_free_kexec_buffer(void)
> {
> - int rc;
> -
> if (!ima_kexec_buffer_size)
> return -ENOENT;
>
> - rc = memblock_phys_free(ima_kexec_buffer_phys,
> - ima_kexec_buffer_size);
> - if (rc)
> - return rc;
> + memblock_free_late(ima_kexec_buffer_phys,
> + ima_kexec_buffer_size);
>
> ima_kexec_buffer_phys = 0;
> ima_kexec_buffer_size = 0;
> diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
> index f26d2ba8a371..68278340cecf 100644
> --- a/drivers/of/kexec.c
> +++ b/drivers/of/kexec.c
> @@ -184,7 +184,8 @@ int __init ima_free_kexec_buffer(void)
> if (ret)
> return ret;
>
> - return memblock_phys_free(addr, size);
> + memblock_free_late(addr, size);
> + return 0;
> }
> #endif
>
> --
> 2.41.0
>
On Fri, 2023-07-21 at 13:38 -0600, Rob Herring wrote:
> On Thu, Jul 20, 2023 at 10:14:31AM -0400, Rik van Riel wrote:
> > The code calling ima_free_kexec_buffer runs long after the memblock
> > allocator has already been torn down, potentially resulting in a
> > use
> > after free in memblock_isolate_range.
> >
> > With KASAN or KFENCE, this use after free will result in a BUG
> > from the idle task, and a subsequent kernel panic.
> >
> > Switch ima_free_kexec_buffer over to memblock_free_late to avoid
> > that issue.
> >
> > Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec
> > functions to drivers/of/kexec.c")
>
> Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on
> kexec")
>
Thank you for digging further back in the history of that code.
> Acked-by: Rob Herring <[email protected]>
>
> (I'm assuming someone else is taking this)
I hope so, but I don't know who...
--
All Rights Reversed.
On Fri, Jul 21, 2023 at 08:40:41PM -0400, Rik van Riel wrote:
> On Fri, 2023-07-21 at 13:38 -0600, Rob Herring wrote:
> > On Thu, Jul 20, 2023 at 10:14:31AM -0400, Rik van Riel wrote:
> > > The code calling ima_free_kexec_buffer runs long after the memblock
> > > allocator has already been torn down, potentially resulting in a
> > > use
> > > after free in memblock_isolate_range.
> > >
> > > With KASAN or KFENCE, this use after free will result in a BUG
> > > from the idle task, and a subsequent kernel panic.
> > >
> > > Switch ima_free_kexec_buffer over to memblock_free_late to avoid
> > > that issue.
> > >
> > > Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec
> > > functions to drivers/of/kexec.c")
> >
> > Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on
> > kexec")
> >
> Thank you for digging further back in the history of that code.
>
> > Acked-by: Rob Herring <[email protected]>
> >
> > (I'm assuming someone else is taking this)
>
> I hope so, but I don't know who...
You could split this into 2 patches, then there's no doubt. And each
Fixes is clear.
Rob