diff options
Diffstat (limited to 'debian/patches/bugfix/all/efi-libstub-fix-efi_random_alloc-to-allocate-memory-.patch')
| -rw-r--r-- | debian/patches/bugfix/all/efi-libstub-fix-efi_random_alloc-to-allocate-memory-.patch | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/debian/patches/bugfix/all/efi-libstub-fix-efi_random_alloc-to-allocate-memory-.patch b/debian/patches/bugfix/all/efi-libstub-fix-efi_random_alloc-to-allocate-memory-.patch new file mode 100644 index 000000000..d5590f5db --- /dev/null +++ b/debian/patches/bugfix/all/efi-libstub-fix-efi_random_alloc-to-allocate-memory-.patch @@ -0,0 +1,68 @@ +From: =?UTF-8?q?KONDO=20KAZUMA=28=E8=BF=91=E8=97=A4=E3=80=80=E5=92=8C?= + =?UTF-8?q?=E7=9C=9F=29?= <kazuma-kondo@nec.com> +Date: Fri, 22 Mar 2024 10:47:02 +0000 +Subject: efi/libstub: fix efi_random_alloc() to allocate memory at alloc_min + or higher address +Origin: https://git.kernel.org/linus/3cb4a4827596abc82e55b80364f509d0fefc3051 + +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> +--- + drivers/firmware/efi/libstub/randomalloc.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +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, +-- +2.43.0 + |