kernel/drivers/firmware/efi/libstub, branch linux-6.9.y

efi/libstub: zboot.lds: Discard .discard sections

2024-07-25T07:53:19Z

[ Upstream commit 5134acb15d9ef27aa2b90aad46d4e89fcef79fdc ] When building ARCH=loongarch defconfig + CONFIG_UNWINDER_ORC=y using LLVM, there is a warning from ld.lld when linking the EFI zboot image due to the use of unreachable() in number() in vsprintf.c: ld.lld: warning: drivers/firmware/efi/libstub/lib.a(vsprintf.stub.o):(.discard.unreachable+0x0): has non-ABS relocation R_LARCH_32_PCREL against symbol '' If the compiler cannot eliminate the default case for any reason, the .discard.unreachable section will remain in the final binary but the entire point of any section prefixed with .discard is that it is only used at compile time, so it can be discarded via /DISCARD/ in a linker script. The asm-generic vmlinux.lds.h includes .discard and .discard.* in the COMMON_DISCARDS macro but that is not used for zboot.lds, as it is not a kernel image linker script. Add .discard and .discard.* to /DISCARD/ in zboot.lds, so that any sections meant to be discarded at link time are not included in the final zboot image. This issue is not specific to LoongArch, it is just the first architecture to select CONFIG_OBJTOOL, which defines annotate_unreachable() as an asm statement to add the .discard.unreachable section, and use the EFI stub. Closes: https://github.com/ClangBuiltLinux/linux/issues/2023 Signed-off-by: Nathan Chancellor Acked-by: Huacai Chen Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

LoongArch: Fix entry point in kernel image header

2024-06-16T11:51:03Z

commit beb2800074c15362cf9f6c7301120910046d6556 upstream. Currently kernel entry in head.S is in DMW address range, firmware is instructed to jump to this address after loading the kernel image. However kernel should not make any assumption on firmware's DMW setting, thus the entry point should be a physical address falls into direct translation region. Fix by converting entry address to physical and amend entry calculation logic in libstub accordingly. BTW, use ABSOLUTE() to calculate variables to make Clang/LLVM happy. Cc: stable@vger.kernel.org Signed-off-by: Jiaxun Yang Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman

efi: libstub: only free priv.runtime_map when allocated

2024-06-12T09:39:57Z

commit 4b2543f7e1e6b91cfc8dd1696e3cdf01c3ac8974 upstream. priv.runtime_map is only allocated when efi_novamap is not set. Otherwise, it is an uninitialized value. In the error path, it is freed unconditionally. Avoid passing an uninitialized value to free_pool. Free priv.runtime_map only when it was allocated. This bug was discovered and resolved using Coverity Static Analysis Security Testing (SAST) by Synopsys, Inc. Fixes: f80d26043af9 ("efi: libstub: avoid efi_get_memory_map() for allocating the virt map") Cc: Signed-off-by: Hagar Hemdan Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

x86/efistub: Omit physical KASLR when memory reservations exist

2024-06-12T09:39:57Z

commit 15aa8fb852f995dd234a57f12dfb989044968bb6 upstream. The legacy decompressor has elaborate logic to ensure that the randomized physical placement of the decompressed kernel image does not conflict with any memory reservations, including ones specified on the command line using mem=, memmap=, efi_fake_mem= or hugepages=, which are taken into account by the kernel proper at a later stage. When booting in EFI mode, it is the firmware's job to ensure that the chosen range does not conflict with any memory reservations that it knows about, and this is trivially achieved by using the firmware's memory allocation APIs. That leaves reservations specified on the command line, though, which the firmware knows nothing about, as these regions have no other special significance to the platform. Since commit a1b87d54f4e4 ("x86/efistub: Avoid legacy decompressor when doing EFI boot") these reservations are not taken into account when randomizing the physical placement, which may result in conflicts where the memory cannot be reserved by the kernel proper because its own executable image resides there. To avoid having to duplicate or reuse the existing complicated logic, disable physical KASLR entirely when such overrides are specified. These are mostly diagnostic tools or niche features, and physical KASLR (as opposed to virtual KASLR, which is much more important as it affects the memory addresses observed by code executing in the kernel) is something we can live without. Closes: https://lkml.kernel.org/r/FA5F6719-8824-4B04-803E-82990E65E627%40akamai.com Reported-by: Ben Chaney Fixes: a1b87d54f4e4 ("x86/efistub: Avoid legacy decompressor when doing EFI boot") Cc: # v6.1+ Reviewed-by: Kees Cook Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

x86/efistub: Reinstate soft limit for initrd loading

2024-03-28T15:19:46Z

Commit 8117961d98fb2 ("x86/efi: Disregard setup header of loaded image") dropped the memcopy of the image's setup header into the boot_params struct provided to the core kernel, on the basis that EFI boot does not need it and should rely only on a single protocol to interface with the boot chain. It is also a prerequisite for being able to increase the section alignment to 4k, which is needed to enable memory protections when running in the boot services. So only the setup_header fields that matter to the core kernel are populated explicitly, and everything else is ignored. One thing was overlooked, though: the initrd_addr_max field in the setup_header is not used by the core kernel, but it is used by the EFI stub itself when it loads the initrd, where its default value of INT_MAX is used as the soft limit for memory allocation. This means that, in the old situation, the initrd was virtually always loaded in the lower 2G of memory, but now, due to initrd_addr_max being 0x0, the initrd may end up anywhere in memory. This should not be an issue principle, as most systems can deal with this fine. However, it does appear to tickle some problems in older UEFI implementations, where the memory ends up being corrupted, resulting in errors when unpacking the initramfs. So set the initrd_addr_max field to INT_MAX like it was before. Fixes: 8117961d98fb2 ("x86/efi: Disregard setup header of loaded image") Reported-by: Radek Podgorny Closes: https://lore.kernel.org/all/a99a831a-8ad5-4cb0-bff9-be637311f771@podgorny.cz Signed-off-by: Ard Biesheuvel

efi/libstub: Cast away type warning in use of max()

2024-03-28T15:18:57Z

Avoid a type mismatch warning in max() by switching to max_t() and providing the type explicitly. Fixes: 3cb4a4827596abc82e ("efi/libstub: fix efi_random_alloc() ...") Signed-off-by: Ard Biesheuvel

Merge tag 'efi-fixes-for-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

2024-03-24T20:54:06Z

Pull EFI fixes from Ard Biesheuvel: - Fix logic that is supposed to prevent placement of the kernel image below LOAD_PHYSICAL_ADDR - Use the firmware stack in the EFI stub when running in mixed mode - Clear BSS only once when using mixed mode - Check efi.get_variable() function pointer for NULL before trying to call it * tag 'efi-fixes-for-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: efi: fix panic in kdump kernel x86/efistub: Don't clear BSS twice in mixed mode x86/efistub: Call mixed mode boot services on the firmware's stack efi/libstub: fix efi_random_alloc() to allocate memory at alloc_min or higher address

x86/efistub: Don't clear BSS twice in mixed mode

2024-03-24T08:28:33Z

Clearing BSS should only be done once, at the very beginning. efi_pe_entry() is the entrypoint from the firmware, which may not clear BSS and so it is done explicitly. However, efi_pe_entry() is also used as an entrypoint by the mixed mode startup code, in which case BSS will already have been cleared, and doing it again at this point will corrupt global variables holding the firmware's GDT/IDT and segment selectors. So make the memset() conditional on whether the EFI stub is running in native mode. Fixes: b3810c5a2cc4a666 ("x86/efistub: Clear decompressor BSS in native EFI entrypoint") Signed-off-by: Ard Biesheuvel

efi/libstub: fix efi_random_alloc() to allocate memory at alloc_min or higher address

2024-03-22T13:08:42Z

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 Cc: linux-kernel@vger.kernel.org Fixes: 2f77465b05b1 ("x86/efistub: Avoid placing the kernel below LOAD_PHYSICAL_ADDR") Signed-off-by: Kazuma Kondo Signed-off-by: Ard Biesheuvel

Merge tag 'efi-fixes-for-v6.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

2024-03-17T19:26:04Z

Pull EFI fix from Ard Biesheuvel: "This fixes an oversight on my part in the recent EFI stub rework for x86, which is needed to get Linux/x86 distro builds signed again for secure boot by Microsoft. For this reason, most of this work is being backported to v6.1, which is therefore also affected by this regression. - Explicitly wipe BSS in the native EFI entrypoint, so that globals shared with the legacy decompressor are zero-initialized correctly" * tag 'efi-fixes-for-v6.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: x86/efistub: Clear decompressor BSS in native EFI entrypoint