This is a note to let you know that I've just added the patch titled
x86/efi: Don't allocate memmap through memblock after mm_init()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-efi-don-t-allocate-memmap-through-memblock-after-mm_init.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 20b1e22d01a4b0b11d3a1066e9feb04be38607ec Mon Sep 17 00:00:00 2001
From: Nicolai Stange <nicstange@xxxxxxxxx>
Date: Thu, 5 Jan 2017 13:51:29 +0100
Subject: x86/efi: Don't allocate memmap through memblock after mm_init()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Nicolai Stange <nicstange@xxxxxxxxx>
commit 20b1e22d01a4b0b11d3a1066e9feb04be38607ec upstream.
With the following commit:
4bc9f92e64c8 ("x86/efi-bgrt: Use efi_mem_reserve() to avoid copying image data")
... efi_bgrt_init() calls into the memblock allocator through
efi_mem_reserve() => efi_arch_mem_reserve() *after* mm_init() has been called.
Indeed, KASAN reports a bad read access later on in efi_free_boot_services():
BUG: KASAN: use-after-free in efi_free_boot_services+0xae/0x24c
at addr ffff88022de12740
Read of size 4 by task swapper/0/0
page:ffffea0008b78480 count:0 mapcount:-127
mapping: (null) index:0x1 flags: 0x5fff8000000000()
[...]
Call Trace:
dump_stack+0x68/0x9f
kasan_report_error+0x4c8/0x500
kasan_report+0x58/0x60
__asan_load4+0x61/0x80
efi_free_boot_services+0xae/0x24c
start_kernel+0x527/0x562
x86_64_start_reservations+0x24/0x26
x86_64_start_kernel+0x157/0x17a
start_cpu+0x5/0x14
The instruction at the given address is the first read from the memmap's
memory, i.e. the read of md->type in efi_free_boot_services().
Note that the writes earlier in efi_arch_mem_reserve() don't splat because
they're done through early_memremap()ed addresses.
So, after memblock is gone, allocations should be done through the "normal"
page allocator. Introduce a helper, efi_memmap_alloc() for this. Use
it from efi_arch_mem_reserve(), efi_free_boot_services() and, for the sake
of consistency, from efi_fake_memmap() as well.
Note that for the latter, the memmap allocations cease to be page aligned.
This isn't needed though.
Tested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Mika Penttilä <mika.penttila@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Fixes: 4bc9f92e64c8 ("x86/efi-bgrt: Use efi_mem_reserve() to avoid copying image data")
Link: http://lkml.kernel.org/r/20170105125130.2815-1-nicstange@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/platform/efi/quirks.c | 4 ++--
drivers/firmware/efi/fake_mem.c | 3 +--
drivers/firmware/efi/memmap.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/efi.h | 1 +
4 files changed, 42 insertions(+), 4 deletions(-)
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -214,7 +214,7 @@ void __init efi_arch_mem_reserve(phys_ad
new_size = efi.memmap.desc_size * num_entries;
- new_phys = memblock_alloc(new_size, 0);
+ new_phys = efi_memmap_alloc(num_entries);
if (!new_phys) {
pr_err("Could not allocate boot services memmap\n");
return;
@@ -355,7 +355,7 @@ void __init efi_free_boot_services(void)
}
new_size = efi.memmap.desc_size * num_entries;
- new_phys = memblock_alloc(new_size, 0);
+ new_phys = efi_memmap_alloc(num_entries);
if (!new_phys) {
pr_err("Failed to allocate new EFI memmap\n");
return;
--- a/drivers/firmware/efi/fake_mem.c
+++ b/drivers/firmware/efi/fake_mem.c
@@ -71,8 +71,7 @@ void __init efi_fake_memmap(void)
}
/* allocate memory for new EFI memmap */
- new_memmap_phy = memblock_alloc(efi.memmap.desc_size * new_nr_map,
- PAGE_SIZE);
+ new_memmap_phy = efi_memmap_alloc(new_nr_map);
if (!new_memmap_phy)
return;
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -9,6 +9,44 @@
#include <linux/efi.h>
#include <linux/io.h>
#include <asm/early_ioremap.h>
+#include <linux/memblock.h>
+#include <linux/slab.h>
+
+static phys_addr_t __init __efi_memmap_alloc_early(unsigned long size)
+{
+ return memblock_alloc(size, 0);
+}
+
+static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
+{
+ unsigned int order = get_order(size);
+ struct page *p = alloc_pages(GFP_KERNEL, order);
+
+ if (!p)
+ return 0;
+
+ return PFN_PHYS(page_to_pfn(p));
+}
+
+/**
+ * efi_memmap_alloc - Allocate memory for the EFI memory map
+ * @num_entries: Number of entries in the allocated map.
+ *
+ * Depending on whether mm_init() has already been invoked or not,
+ * either memblock or "normal" page allocation is used.
+ *
+ * Returns the physical address of the allocated memory map on
+ * success, zero on failure.
+ */
+phys_addr_t __init efi_memmap_alloc(unsigned int num_entries)
+{
+ unsigned long size = num_entries * efi.memmap.desc_size;
+
+ if (slab_is_available())
+ return __efi_memmap_alloc_late(size);
+
+ return __efi_memmap_alloc_early(size);
+}
/**
* __efi_memmap_init - Common code for mapping the EFI memory map
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -931,6 +931,7 @@ static inline efi_status_t efi_query_var
#endif
extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);
+extern phys_addr_t __init efi_memmap_alloc(unsigned int num_entries);
extern int __init efi_memmap_init_early(struct efi_memory_map_data *data);
extern int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size);
extern void __init efi_memmap_unmap(void);
Patches currently in stable-queue which might be from nicstange@xxxxxxxxx are
queue-4.9/x86-efi-don-t-allocate-memmap-through-memblock-after-mm_init.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html