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authorHans de Goede <hdegoede@redhat.com>2018-05-04 08:00:01 +0200
committerIngo Molnar <mingo@kernel.org>2018-05-14 08:57:49 +0200
commit1de3a1be8a9345fd0c7d9bb1009b21afe6b6b10f (patch)
treeff183153fffd8b0d699bb330502d1e7e0adffa80 /arch/x86/boot
parent2c3625cb9fa2c477d5877a1819e29d6a902e5fef (diff)
efi/x86: Ignore unrealistically large option ROMs
setup_efi_pci() tries to save a copy of each PCI option ROM as this may be necessary for the device driver for the PCI device to have access too. On some systems the efi_pci_io_protocol's romimage and romsize fields contain invalid data, which looks a bit like pointers pointing back into other EFI code or data. Interpreting these pointers as romsize leads to a very large value and if we then try to alloc this amount of memory to save a copy the alloc call fails. This leads to a "Failed to alloc mem for rom" error being printed on the EFI console for each PCI device. This commit avoids the printing of these errors, by checking romsize before doing the alloc and if it is larger then the EFI spec limit of 16 MiB silently ignore the ROM fields instead of trying to alloc mem and fail. Tested-by: Hans de Goede <hdegoede@redhat.com> [ardb: deduplicate 32/64 bit changes, use SZ_16M symbolic constant] Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20180504060003.19618-16-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/boot')
-rw-r--r--arch/x86/boot/compressed/eboot.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index dadf32312082..a8a8642d2b0b 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -123,10 +123,17 @@ __setup_efi_pci(efi_pci_io_protocol_t *pci, struct pci_setup_rom **__rom)
if (status != EFI_SUCCESS)
return status;
+ /*
+ * Some firmware images contain EFI function pointers at the place where the
+ * romimage and romsize fields are supposed to be. Typically the EFI
+ * code is mapped at high addresses, translating to an unrealistically
+ * large romsize. The UEFI spec limits the size of option ROMs to 16
+ * MiB so we reject any ROMs over 16 MiB in size to catch this.
+ */
romimage = (void *)(unsigned long)efi_table_attr(efi_pci_io_protocol,
romimage, pci);
romsize = efi_table_attr(efi_pci_io_protocol, romsize, pci);
- if (!romimage || !romsize)
+ if (!romimage || !romsize || romsize > SZ_16M)
return EFI_INVALID_PARAMETER;
size = romsize + sizeof(*rom);