2021-08-11 08:59:06

by Geert Uytterhoeven

Subject: [PATCH] memblock: Check memory add/cap ordering

For memblock_cap_memory_range() to work properly, it should be called
after memory is detected and added to memblock with memblock_add() or
memblock_add_node(). If memblock_cap_memory_range() would be called
before memory is registered, we may silently corrupt memory later
because the crash kernel will see all memory as available.

Print a warning and bail out if ordering is not satisfied.

Suggested-by: Mike Rapoport <[email protected]>
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
mm/memblock.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/mm/memblock.c b/mm/memblock.c
index 57a9849a5d820c34..e2ca8ddc8ebebf4e 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1685,6 +1685,11 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
if (!size)
return;

+ if (memblock.memory.cnt <= 1) {
+ pr_warn("%s: No memory registered yet\n", __func__);
+ return;
+ }
+
ret = memblock_isolate_range(&memblock.memory, base, size,
&start_rgn, &end_rgn);
if (ret)
--
2.25.1

2021-08-11 09:38:47

by David Hildenbrand

Subject: Re: [PATCH] memblock: Check memory add/cap ordering

On 11.08.21 10:55, Geert Uytterhoeven wrote:
> For memblock_cap_memory_range() to work properly, it should be called
> after memory is detected and added to memblock with memblock_add() or
> memblock_add_node(). If memblock_cap_memory_range() would be called
> before memory is registered, we may silently corrupt memory later
> because the crash kernel will see all memory as available.
>
> Print a warning and bail out if ordering is not satisfied.
>
> Suggested-by: Mike Rapoport <[email protected]>
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> ---
> mm/memblock.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 57a9849a5d820c34..e2ca8ddc8ebebf4e 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1685,6 +1685,11 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
> if (!size)
> return;
>
> + if (memblock.memory.cnt <= 1) {
> + pr_warn("%s: No memory registered yet\n", __func__);
> + return;
> + }
> +
> ret = memblock_isolate_range(&memblock.memory, base, size,
> &start_rgn, &end_rgn);
> if (ret)
>

Reviewed-by: David Hildenbrand <[email protected]>

--
Thanks,

David / dhildenb

2021-08-11 13:08:33

by Mike Rapoport

Subject: Re: [PATCH] memblock: Check memory add/cap ordering

On Wed, Aug 11, 2021 at 10:55:18AM +0200, Geert Uytterhoeven wrote:
> For memblock_cap_memory_range() to work properly, it should be called
> after memory is detected and added to memblock with memblock_add() or
> memblock_add_node(). If memblock_cap_memory_range() would be called
> before memory is registered, we may silently corrupt memory later
> because the crash kernel will see all memory as available.
>
> Print a warning and bail out if ordering is not satisfied.
>
> Suggested-by: Mike Rapoport <[email protected]>
> Signed-off-by: Geert Uytterhoeven <[email protected]>

Applied for 5.15,
Thanks!

--
Sincerely yours,
Mike.