On 5/12/25 05:34, gregkh@linuxfoundation.org wrote:
This is a note to let you know that I've just added the patch titled
memblock: Accept allocated memory before use in memblock_double_array()to the 6.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: memblock-accept-allocated-memory-before-use-in-memblock_double_array.patch and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
The 6.6 version of the patch needs a fixup. As mentioned in the patch description, any release before v6.12 needs to have the accept_memory() call changed from:
accept_memory(addr, new_alloc_size);
to
accept_memory(addr, addr + new_alloc_size);
Do you need for me to send a v6.6 specific patch?
Thanks, Tom
From da8bf5daa5e55a6af2b285ecda460d6454712ff4 Mon Sep 17 00:00:00 2001 From: Tom Lendacky thomas.lendacky@amd.com Date: Thu, 8 May 2025 12:24:10 -0500 Subject: memblock: Accept allocated memory before use in memblock_double_array()
From: Tom Lendacky thomas.lendacky@amd.com
commit da8bf5daa5e55a6af2b285ecda460d6454712ff4 upstream.
When increasing the array size in memblock_double_array() and the slab is not yet available, a call to memblock_find_in_range() is used to reserve/allocate memory. However, the range returned may not have been accepted, which can result in a crash when booting an SNP guest:
RIP: 0010:memcpy_orig+0x68/0x130 Code: ... RSP: 0000:ffffffff9cc03ce8 EFLAGS: 00010006 RAX: ff11001ff83e5000 RBX: 0000000000000000 RCX: fffffffffffff000 RDX: 0000000000000bc0 RSI: ffffffff9dba8860 RDI: ff11001ff83e5c00 RBP: 0000000000002000 R08: 0000000000000000 R09: 0000000000002000 R10: 000000207fffe000 R11: 0000040000000000 R12: ffffffff9d06ef78 R13: ff11001ff83e5000 R14: ffffffff9dba7c60 R15: 0000000000000c00 memblock_double_array+0xff/0x310 memblock_add_range+0x1fb/0x2f0 memblock_reserve+0x4f/0xa0 memblock_alloc_range_nid+0xac/0x130 memblock_alloc_internal+0x53/0xc0 memblock_alloc_try_nid+0x3d/0xa0 swiotlb_init_remap+0x149/0x2f0 mem_init+0xb/0xb0 mm_core_init+0x8f/0x350 start_kernel+0x17e/0x5d0 x86_64_start_reservations+0x14/0x30 x86_64_start_kernel+0x92/0xa0 secondary_startup_64_no_verify+0x194/0x19b
Mitigate this by calling accept_memory() on the memory range returned before the slab is available.
Prior to v6.12, the accept_memory() interface used a 'start' and 'end' parameter instead of 'start' and 'size', therefore the accept_memory() call must be adjusted to specify 'start + size' for 'end' when applying to kernels prior to v6.12.
Cc: stable@vger.kernel.org # see patch description, needs adjustments for <= 6.11 Fixes: dcdfdd40fa82 ("mm: Add support for unaccepted memory") Signed-off-by: Tom Lendacky thomas.lendacky@amd.com Link: https://lore.kernel.org/r/da1ac73bf4ded761e21b4e4bb5178382a580cd73.174672505... Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
mm/memblock.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/mm/memblock.c +++ b/mm/memblock.c @@ -460,7 +460,14 @@ static int __init_memblock memblock_doub min(new_area_start, memblock.current_limit), new_alloc_size, PAGE_SIZE);
new_array = addr ? __va(addr) : NULL;
if (addr) {/* The memory may not have been accepted, yet. */accept_memory(addr, new_alloc_size);new_array = __va(addr);} else {new_array = NULL;}Patches currently in stable-queue which might be from thomas.lendacky@amd.com are
queue-6.6/memblock-accept-allocated-memory-before-use-in-memblock_double_array.patch