From: Geert Uytterhoeven Date: Wed, 11 Aug 2021 08:55:18 +0000 (+0200) Subject: memblock: Check memory add/cap ordering X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e888fa7bb882a1f305526d8f49d7016a7bc5f5ca;p=linux.git 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 Signed-off-by: Geert Uytterhoeven Reviewed-by: David Hildenbrand Signed-off-by: Mike Rapoport Link: https://lore.kernel.org/r/aabc5bad008d49f07d542815c6c8d28ec90bb09e.1628672091.git.geert+renesas@glider.be --- diff --git a/mm/memblock.c b/mm/memblock.c index 57a9849a5d820..e2ca8ddc8ebeb 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)