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authorKONDO KAZUMA(近藤 和真) <kazuma-kondo@nec.com>2024-03-22 10:47:02 +0000
committerArd Biesheuvel <ardb@kernel.org>2024-03-22 14:08:42 +0100
commit3cb4a4827596abc82e55b80364f509d0fefc3051 (patch)
tree5dad276ba819b2e98fc722428de408131be4b38e
parentb3810c5a2cc4a6665f7a65bed5393c75ce3f3aa2 (diff)
efi/libstub: fix efi_random_alloc() to allocate memory at alloc_min or higher address
Following warning is sometimes observed while booting my servers: [ 3.594838] DMA: preallocated 4096 KiB GFP_KERNEL pool for atomic allocations [ 3.602918] swapper/0: page allocation failure: order:10, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0-1 ... [ 3.851862] DMA: preallocated 1024 KiB GFP_KERNEL|GFP_DMA pool for atomic allocation If 'nokaslr' boot option is set, the warning always happens. On x86, ZONE_DMA is small zone at the first 16MB of physical address space. When this problem happens, most of that space seems to be used by decompressed kernel. Thereby, there is not enough space at DMA_ZONE to meet the request of DMA pool allocation. The commit 2f77465b05b1 ("x86/efistub: Avoid placing the kernel below LOAD_PHYSICAL_ADDR") tried to fix this problem by introducing lower bound of allocation. But the fix is not complete. efi_random_alloc() allocates pages by following steps. 1. Count total available slots ('total_slots') 2. Select a slot ('target_slot') to allocate randomly 3. Calculate a starting address ('target') to be included target_slot 4. Allocate pages, which starting address is 'target' In step 1, 'alloc_min' is used to offset the starting address of memory chunk. But in step 3 'alloc_min' is not considered at all. As the result, 'target' can be miscalculated and become lower than 'alloc_min'. When KASLR is disabled, 'target_slot' is always 0 and the problem happens everytime if the EFI memory map of the system meets the condition. Fix this problem by calculating 'target' considering 'alloc_min'. Cc: linux-efi@vger.kernel.org Cc: Tom Englund <tomenglund26@gmail.com> Cc: linux-kernel@vger.kernel.org Fixes: 2f77465b05b1 ("x86/efistub: Avoid placing the kernel below LOAD_PHYSICAL_ADDR") Signed-off-by: Kazuma Kondo <kazuma-kondo@nec.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
-rw-r--r--drivers/firmware/efi/libstub/randomalloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
index 4e96a855fdf4..7e1852859550 100644
--- a/drivers/firmware/efi/libstub/randomalloc.c
+++ b/drivers/firmware/efi/libstub/randomalloc.c
@@ -120,7 +120,7 @@ efi_status_t efi_random_alloc(unsigned long size,
continue;
}
- target = round_up(md->phys_addr, align) + target_slot * align;
+ target = round_up(max(md->phys_addr, alloc_min), align) + target_slot * align;
pages = size / EFI_PAGE_SIZE;
status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,