3cc028619e
When installing the EFI virtual address map during early boot, we access the EFI system table to retrieve the 1:1 mapped address of the SetVirtualAddressMap() EFI runtime service. This memory is not known to KASAN, so on KASAN enabled builds, this may result in a splat like ================================================================== BUG: KASAN: user-memory-access in efi_set_virtual_address_map+0x141/0x354 Read of size 4 at addr 000000003fbeef38 by task swapper/0/0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.5.0-rc5+ #758 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack+0x8b/0xbb ? efi_set_virtual_address_map+0x141/0x354 ? efi_set_virtual_address_map+0x141/0x354 __kasan_report+0x176/0x192 ? efi_set_virtual_address_map+0x141/0x354 kasan_report+0xe/0x20 efi_set_virtual_address_map+0x141/0x354 ? efi_thunk_runtime_setup+0x148/0x148 ? __inc_numa_state+0x19/0x90 ? memcpy+0x34/0x50 efi_enter_virtual_mode+0x5fd/0x67d start_kernel+0x5cd/0x682 ? mem_encrypt_init+0x6/0x6 ? x86_family+0x5/0x20 ? load_ucode_bsp+0x46/0x154 secondary_startup_64+0xa4/0xb0 ================================================================== Since this code runs only a single time during early boot, let's annotate it as __no_sanitize_address so KASAN disregards it entirely. Fixes: 698294704573 ("efi/x86: Split SetVirtualAddresMap() wrappers into ...") Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.