kernel.git/drivers/firmware/efi, branch linux-6.1.y

EFI/CPER: don't go past the ARM processor CPER record buffer

2026-03-04T12:20:14Z

[ Upstream commit eae21beecb95a3b69ee5c38a659f774e171d730e ] There's a logic inside GHES/CPER to detect if the section_length is too small, but it doesn't detect if it is too big. Currently, if the firmware receives an ARM processor CPER record stating that a section length is big, kernel will blindly trust section_length, producing a very long dump. For instance, a 67 bytes record with ERR_INFO_NUM set 46198 and section length set to 854918320 would dump a lot of data going a way past the firmware memory-mapped area. Fix it by adding a logic to prevent it to go past the buffer if ERR_INFO_NUM is too big, making it report instead: [Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1 [Hardware Error]: event severity: recoverable [Hardware Error]: Error 0, type: recoverable [Hardware Error]: section_type: ARM processor error [Hardware Error]: MIDR: 0xff304b2f8476870a [Hardware Error]: section length: 854918320, CPER size: 67 [Hardware Error]: section length is too big [Hardware Error]: firmware-generated error record is incorrect [Hardware Error]: ERR_INFO_NUM is 46198 Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Ard Biesheuvel Reviewed-by: Hanjun Guo [ rjw: Subject and changelog tweaks ] Link: https://patch.msgid.link/41cd9f6b3ace3cdff7a5e864890849e4b1c58b63.1767871950.git.mchehab+huawei@kernel.org Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

EFI/CPER: don't dump the entire memory region

2026-03-04T12:20:14Z

[ Upstream commit 55cc6fe5716f678f06bcb95140882dfa684464ec ] The current logic at cper_print_fw_err() doesn't check if the error record length is big enough to handle offset. On a bad firmware, if the ofset is above the actual record, length -= offset will underflow, making it dump the entire memory. The end result can be: - the logic taking a lot of time dumping large regions of memory; - data disclosure due to the memory dumps; - an OOPS, if it tries to dump an unmapped memory region. Fix it by checking if the section length is too small before doing a hex dump. Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Ard Biesheuvel Reviewed-by: Hanjun Guo [ rjw: Subject tweaks ] Link: https://patch.msgid.link/1752b5ba63a3e2f148ddee813b36c996cc617e86.1767871950.git.mchehab+huawei@kernel.org Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

efi/cper: Fix cper_bits_to_str buffer handling and return value

2026-02-06T15:43:53Z

commit d7f1b4bdc7108be1b178e1617b5f45c8918e88d7 upstream. The return value calculation was incorrect: `return len - buf_size;` Initially `len = buf_size`, then `len` decreases with each operation. This results in a negative return value on success. Fix by returning `buf_size - len` which correctly calculates the actual number of bytes written. Fixes: a976d790f494 ("efi/cper: Add a new helper function to print bitmasks") Signed-off-by: Morduan Zang Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

efi/cper: align ARM CPER type with UEFI 2.9A/2.10 specs

2026-01-11T14:18:38Z

[ Upstream commit 96b010536ee020e716d28d9b359a4bcd18800aeb ] Up to UEFI spec 2.9, the type byte of CPER struct for ARM processor was defined simply as: Type at byte offset 4: - Cache error - TLB Error - Bus Error - Micro-architectural Error All other values are reserved Yet, there was no information about how this would be encoded. Spec 2.9A errata corrected it by defining: - Bit 1 - Cache Error - Bit 2 - TLB Error - Bit 3 - Bus Error - Bit 4 - Micro-architectural Error All other values are reserved That actually aligns with the values already defined on older versions at N.2.4.1. Generic Processor Error Section. Spec 2.10 also preserve the same encoding as 2.9A. Adjust CPER and GHES handling code for both generic and ARM processors to properly handle UEFI 2.9A and 2.10 encoding. Link: https://uefi.org/specs/UEFI/2.10/Apx_N_Common_Platform_Error_Record.html#arm-processor-error-information Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Borislav Petkov (AMD) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/cper: Adjust infopfx size to accept an extra space

2026-01-11T14:18:37Z

[ Upstream commit 8ad2c72e21efb3dc76c5b14089fa7984cdd87898 ] Compiling with W=1 with werror enabled produces an error: drivers/firmware/efi/cper-arm.c: In function ‘cper_print_proc_arm’: drivers/firmware/efi/cper-arm.c:298:64: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=] 298 | snprintf(infopfx, sizeof(infopfx), "%s ", newpfx); | ^ drivers/firmware/efi/cper-arm.c:298:25: note: ‘snprintf’ output between 2 and 65 bytes into a destination of size 64 298 | snprintf(infopfx, sizeof(infopfx), "%s ", newpfx); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As the logic there adds an space at the end of infopx buffer. Add an extra space to avoid such warning. Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Borislav Petkov (AMD) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/cper: Add a new helper function to print bitmasks

2026-01-11T14:18:37Z

[ Upstream commit a976d790f49499ccaa0f991788ad8ebf92e7fd5c ] Add a helper function to print a string with names associated to each bit field. A typical example is: const char * const bits[] = { "bit 3 name", "bit 4 name", "bit 5 name", }; char str[120]; unsigned int bitmask = BIT(3) | BIT(5); #define MASK GENMASK(5,3) cper_bits_to_str(str, sizeof(str), FIELD_GET(MASK, bitmask), bits, ARRAY_SIZE(bits)); The above code fills string "str" with "bit 3 name|bit 5 name". Reviewed-by: Jonathan Cameron Signed-off-by: Mauro Carvalho Chehab Acked-by: Borislav Petkov (AMD) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/libstub: Fix page table access in 5-level to 4-level paging transition

2026-01-11T14:18:22Z

[ Upstream commit 84361123413efc84b06f3441c6c827b95d902732 ] When transitioning from 5-level to 4-level paging, the existing code incorrectly accesses page table entries by directly dereferencing CR3 and applying PAGE_MASK. This approach has several issues: - __native_read_cr3() returns the raw CR3 register value, which on x86_64 includes not just the physical address but also flags Bits above the physical address width of the system (i.e. above __PHYSICAL_MASK_SHIFT) are also not masked. - The pgd value is masked by PAGE_SIZE which doesn't take into account the higher bits such as _PAGE_BIT_NOPTISHADOW. Replace this with proper accessor functions: - native_read_cr3_pa(): Uses CR3_ADDR_MASK to additionally mask metadata out of CR3 (like SME or LAM bits). All remaining bits are real address bits or reserved and must be 0. - mask pgd value with PTE_PFN_MASK instead of PAGE_MASK, accounting for flags above bit 51 (_PAGE_BIT_NOPTISHADOW in particular). Bits below 51, but above the max physical address are reserved and must be 0. Fixes: cb1c9e02b0c1 ("x86/efistub: Perform 4/5 level paging switch from the stub") Reported-by: Michael van der Westhuizen Reported-by: Tobias Fleig Co-developed-by: Kiryl Shutsemau Signed-off-by: Kiryl Shutsemau Signed-off-by: Usama Arif Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Ard Biesheuvel Link: https://patch.msgid.link/20251103141002.2280812-3-usamaarif642@gmail.com Signed-off-by: Sasha Levin

efi/libstub: Describe missing 'out' parameter in efi_load_initrd

2025-06-27T10:07:10Z

[ Upstream commit c8e1927e7f7d63721e32ec41d27ccb0eb1a1b0fc ] The function efi_load_initrd() had a documentation warning due to the missing description for the 'out' parameter. Add the parameter description to the kernel-doc comment to resolve the warning and improve API documentation. Fixes the following compiler warning: drivers/firmware/efi/libstub/efi-stub-helper.c:611: warning: Function parameter or struct member 'out' not described in 'efi_load_initrd' Fixes: f4dc7fffa987 ("efi: libstub: unify initrd loading between architectures") Signed-off-by: Hans Zhang <18255117159@163.com> Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/libstub: Avoid physical address 0x0 when doing random allocation

2025-03-28T20:59:01Z

commit cb16dfed0093217a68c0faa9394fa5823927e04c upstream. Ben reports spurious EFI zboot failures on a system where physical RAM starts at 0x0. When doing random memory allocation from the EFI stub on such a platform, a random seed of 0x0 (which means no entropy source is available) will result in the allocation to be placed at address 0x0 if sufficient space is available. When this allocation is subsequently passed on to the decompression code, the 0x0 address is mistaken for NULL and the code complains and gives up. So avoid address 0x0 when doing random allocation, and set the minimum address to the minimum alignment. Cc: Reported-by: Ben Schneider Tested-by: Ben Schneider Reviewed-by: Ilias Apalodimas Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

efi: Avoid cold plugged memory for placing the kernel

2025-02-21T12:50:04Z

commit ba69e0750b0362870294adab09339a0c39c3beaf upstream. UEFI 2.11 introduced EFI_MEMORY_HOT_PLUGGABLE to annotate system memory regions that are 'cold plugged' at boot, i.e., hot pluggable memory that is available from early boot, and described as system RAM by the firmware. Existing loaders and EFI applications running in the boot context will happily use this memory for allocating data structures that cannot be freed or moved at runtime, and this prevents the memory from being unplugged. Going forward, the new EFI_MEMORY_HOT_PLUGGABLE attribute should be tested, and memory annotated as such should be avoided for such allocations. In the EFI stub, there are a couple of occurrences where, instead of the high-level AllocatePages() UEFI boot service, a low-level code sequence is used that traverses the EFI memory map and carves out the requested number of pages from a free region. This is needed, e.g., for allocating as low as possible, or for allocating pages at random. While AllocatePages() should presumably avoid special purpose memory and cold plugged regions, this manual approach needs to incorporate this logic itself, in order to prevent the kernel itself from ending up in a hot unpluggable region, preventing it from being unplugged. So add the EFI_MEMORY_HOTPLUGGABLE macro definition, and check for it where appropriate. Cc: stable@vger.kernel.org Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman