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[x86] efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y

This commit is contained in:
Ben Hutchings 2016-11-13 21:00:47 +00:00
parent b15e0cf459
commit 9ab8cb710b
3 changed files with 214 additions and 0 deletions
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1
debian/changelog vendored
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@ -19,6 +19,7 @@ linux (4.9~rc5-1~exp1) UNRELEASED; urgency=medium
* [armel] Drop versatile flavour, which has been broken since version
4.5~rc4-1~exp1
* [x86] ethernet: Enable ENA_ETHERNET as module
* [x86] efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y
-- Aurelien Jarno <aurel32@debian.org> Sat, 05 Nov 2016 23:17:01 +0100

212
debian/patches/bugfix/x86/x86-efi-prevent-mixed-mode-boot-corruption-with-conf.patch vendored Normal file
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@ -0,0 +1,212 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Sat, 12 Nov 2016 21:04:24 +0000
Subject: x86/efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y
Origin: https://git.kernel.org/linus/f6697df36bdf0bf7fce984605c2918d4a7b4269f
Booting an EFI mixed mode kernel has been crashing since commit:
e37e43a497d5 ("x86/mm/64: Enable vmapped stacks (CONFIG_HAVE_ARCH_VMAP_STACK=y)")
The user-visible effect in my test setup was the kernel being unable
to find the root file system ramdisk. This was likely caused by silent
memory or page table corruption.
Enabling CONFIG_DEBUG_VIRTUAL=y immediately flagged the thunking code as
abusing virt_to_phys() because it was passing addresses that were not
part of the kernel direct mapping.
Use the slow version instead, which correctly handles all memory
regions by performing a page table walk.
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112210424.5157-3-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/platform/efi/efi_64.c | 80 ++++++++++++++++++++++++++++++------------
1 file changed, 57 insertions(+), 23 deletions(-)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -31,6 +31,7 @@
#include <linux/io.h>
#include <linux/reboot.h>
#include <linux/slab.h>
+#include <linux/ucs2_string.h>
#include <asm/setup.h>
#include <asm/page.h>
@@ -211,6 +212,35 @@ void efi_sync_low_kernel_mappings(void)
memcpy(pud_efi, pud_k, sizeof(pud_t) * num_entries);
}
+/*
+ * Wrapper for slow_virt_to_phys() that handles NULL addresses.
+ */
+static inline phys_addr_t
+virt_to_phys_or_null_size(void *va, unsigned long size)
+{
+ bool bad_size;
+
+ if (!va)
+ return 0;
+
+ if (virt_addr_valid(va))
+ return virt_to_phys(va);
+
+ /*
+ * A fully aligned variable on the stack is guaranteed not to
+ * cross a page bounary. Try to catch strings on the stack by
+ * checking that 'size' is a power of two.
+ */
+ bad_size = size > PAGE_SIZE || !is_power_of_2(size);
+
+ WARN_ON(!IS_ALIGNED((unsigned long)va, size) || bad_size);
+
+ return slow_virt_to_phys(va);
+}
+
+#define virt_to_phys_or_null(addr) \
+ virt_to_phys_or_null_size((addr), sizeof(*(addr)))
+
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
unsigned long pfn, text;
@@ -494,8 +524,8 @@ static efi_status_t efi_thunk_get_time(e
spin_lock(&rtc_lock);
- phys_tm = virt_to_phys(tm);
- phys_tc = virt_to_phys(tc);
+ phys_tm = virt_to_phys_or_null(tm);
+ phys_tc = virt_to_phys_or_null(tc);
status = efi_thunk(get_time, phys_tm, phys_tc);
@@ -511,7 +541,7 @@ static efi_status_t efi_thunk_set_time(e
spin_lock(&rtc_lock);
- phys_tm = virt_to_phys(tm);
+ phys_tm = virt_to_phys_or_null(tm);
status = efi_thunk(set_time, phys_tm);
@@ -529,9 +559,9 @@ efi_thunk_get_wakeup_time(efi_bool_t *en
spin_lock(&rtc_lock);
- phys_enabled = virt_to_phys(enabled);
- phys_pending = virt_to_phys(pending);
- phys_tm = virt_to_phys(tm);
+ phys_enabled = virt_to_phys_or_null(enabled);
+ phys_pending = virt_to_phys_or_null(pending);
+ phys_tm = virt_to_phys_or_null(tm);
status = efi_thunk(get_wakeup_time, phys_enabled,
phys_pending, phys_tm);
@@ -549,7 +579,7 @@ efi_thunk_set_wakeup_time(efi_bool_t ena
spin_lock(&rtc_lock);
- phys_tm = virt_to_phys(tm);
+ phys_tm = virt_to_phys_or_null(tm);
status = efi_thunk(set_wakeup_time, enabled, phys_tm);
@@ -558,6 +588,10 @@ efi_thunk_set_wakeup_time(efi_bool_t ena
return status;
}
+static unsigned long efi_name_size(efi_char16_t *name)
+{
+ return ucs2_strsize(name, EFI_VAR_NAME_LEN) + 1;
+}
static efi_status_t
efi_thunk_get_variable(efi_char16_t *name, efi_guid_t *vendor,
@@ -567,11 +601,11 @@ efi_thunk_get_variable(efi_char16_t *nam
u32 phys_name, phys_vendor, phys_attr;
u32 phys_data_size, phys_data;
- phys_data_size = virt_to_phys(data_size);
- phys_vendor = virt_to_phys(vendor);
- phys_name = virt_to_phys(name);
- phys_attr = virt_to_phys(attr);
- phys_data = virt_to_phys(data);
+ phys_data_size = virt_to_phys_or_null(data_size);
+ phys_vendor = virt_to_phys_or_null(vendor);
+ phys_name = virt_to_phys_or_null_size(name, efi_name_size(name));
+ phys_attr = virt_to_phys_or_null(attr);
+ phys_data = virt_to_phys_or_null_size(data, *data_size);
status = efi_thunk(get_variable, phys_name, phys_vendor,
phys_attr, phys_data_size, phys_data);
@@ -586,9 +620,9 @@ efi_thunk_set_variable(efi_char16_t *nam
u32 phys_name, phys_vendor, phys_data;
efi_status_t status;
- phys_name = virt_to_phys(name);
- phys_vendor = virt_to_phys(vendor);
- phys_data = virt_to_phys(data);
+ phys_name = virt_to_phys_or_null_size(name, efi_name_size(name));
+ phys_vendor = virt_to_phys_or_null(vendor);
+ phys_data = virt_to_phys_or_null_size(data, data_size);
/* If data_size is > sizeof(u32) we've got problems */
status = efi_thunk(set_variable, phys_name, phys_vendor,
@@ -605,9 +639,9 @@ efi_thunk_get_next_variable(unsigned lon
efi_status_t status;
u32 phys_name_size, phys_name, phys_vendor;
- phys_name_size = virt_to_phys(name_size);
- phys_vendor = virt_to_phys(vendor);
- phys_name = virt_to_phys(name);
+ phys_name_size = virt_to_phys_or_null(name_size);
+ phys_vendor = virt_to_phys_or_null(vendor);
+ phys_name = virt_to_phys_or_null_size(name, *name_size);
status = efi_thunk(get_next_variable, phys_name_size,
phys_name, phys_vendor);
@@ -621,7 +655,7 @@ efi_thunk_get_next_high_mono_count(u32 *
efi_status_t status;
u32 phys_count;
- phys_count = virt_to_phys(count);
+ phys_count = virt_to_phys_or_null(count);
status = efi_thunk(get_next_high_mono_count, phys_count);
return status;
@@ -633,7 +667,7 @@ efi_thunk_reset_system(int reset_type, e
{
u32 phys_data;
- phys_data = virt_to_phys(data);
+ phys_data = virt_to_phys_or_null_size(data, data_size);
efi_thunk(reset_system, reset_type, status, data_size, phys_data);
}
@@ -661,9 +695,9 @@ efi_thunk_query_variable_info(u32 attr,
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- phys_storage = virt_to_phys(storage_space);
- phys_remaining = virt_to_phys(remaining_space);
- phys_max = virt_to_phys(max_variable_size);
+ phys_storage = virt_to_phys_or_null(storage_space);
+ phys_remaining = virt_to_phys_or_null(remaining_space);
+ phys_max = virt_to_phys_or_null(max_variable_size);
status = efi_thunk(query_variable_info, attr, phys_storage,
phys_remaining, phys_max);

1
debian/patches/series vendored
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@ -47,6 +47,7 @@ debian/fanotify-taint-on-use-of-fanotify_access_permissions.patch
# Arch bug fixes
bugfix/arm64/arm64-mm-limit-task_size_64-for-compatibility.patch
bugfix/x86/x86-efi-prevent-mixed-mode-boot-corruption-with-conf.patch
# Arch features
features/mips/MIPS-increase-MAX-PHYSMEM-BITS-on-Loongson-3-only.patch