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Message-ID: <a43179e8-b063-569c-f27d-dda84133322e@oracle.com>
Date: Thu, 25 Feb 2021 11:06:12 -0500
From: George Kennedy <george.kennedy@...cle.com>
To: Mike Rapoport <rppt@...ux.ibm.com>
Cc: David Hildenbrand <david@...hat.com>,
Andrey Konovalov <andreyknvl@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Catalin Marinas <catalin.marinas@....com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Konrad Rzeszutek Wilk <konrad@...nok.org>,
Will Deacon <will.deacon@....com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Alexander Potapenko <glider@...gle.com>,
Marco Elver <elver@...gle.com>,
Peter Collingbourne <pcc@...gle.com>,
Evgenii Stepanov <eugenis@...gle.com>,
Branislav Rankov <Branislav.Rankov@....com>,
Kevin Brodsky <kevin.brodsky@....com>,
Christoph Hellwig <hch@...radead.org>,
kasan-dev <kasan-dev@...glegroups.com>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux Memory Management List <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
Dhaval Giani <dhaval.giani@...cle.com>
Subject: Re: [PATCH] mm, kasan: don't poison boot memory
On 2/25/2021 10:22 AM, George Kennedy wrote:
>
>
> On 2/25/2021 9:57 AM, Mike Rapoport wrote:
>> On Thu, Feb 25, 2021 at 07:38:19AM -0500, George Kennedy wrote:
>>> On 2/25/2021 3:53 AM, Mike Rapoport wrote:
>>>> Hi George,
>>>>
>>>>> On 2/24/2021 5:37 AM, Mike Rapoport wrote:
>>>>>> On Tue, Feb 23, 2021 at 04:46:28PM -0500, George Kennedy wrote:
>>>>>>> Mike,
>>>>>>>
>>>>>>> Still no luck.
>>>>>>>
>>>>>>> [ 30.193723] iscsi: registered transport (iser)
>>>>>>> [ 30.195970] iBFT detected.
>>>>>>> [ 30.196571] BUG: unable to handle page fault for address:
>>>>>>> ffffffffff240004
>>>>>> Hmm, we cannot set ibft_addr to early pointer to the ACPI table.
>>>>>> Let's try something more disruptive and move the reservation back to
>>>>>> iscsi_ibft_find.c.
>>>>>>
>>>>>> diff --git a/arch/x86/kernel/acpi/boot.c
>>>>>> b/arch/x86/kernel/acpi/boot.c
>>>>>> index 7bdc0239a943..c118dd54a747 100644
>>>>>> --- a/arch/x86/kernel/acpi/boot.c
>>>>>> +++ b/arch/x86/kernel/acpi/boot.c
>>>>>> @@ -1551,6 +1551,7 @@ void __init acpi_boot_table_init(void)
>>>>>> if (acpi_disabled)
>>>>>> return;
>>>>>> +#if 0
>>>>>> /*
>>>>>> * Initialize the ACPI boot-time table parser.
>>>>>> */
>>>>>> @@ -1558,6 +1559,7 @@ void __init acpi_boot_table_init(void)
>>>>>> disable_acpi();
>>>>>> return;
>>>>>> }
>>>>>> +#endif
>>>>>> acpi_table_parse(ACPI_SIG_BOOT, acpi_parse_sbf);
>>>>>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>>>>>> index d883176ef2ce..c615ce96c9a2 100644
>>>>>> --- a/arch/x86/kernel/setup.c
>>>>>> +++ b/arch/x86/kernel/setup.c
>>>>>> @@ -570,16 +570,6 @@ void __init reserve_standard_io_resources(void)
>>>>>> }
>>>>>> -static __init void reserve_ibft_region(void)
>>>>>> -{
>>>>>> - unsigned long addr, size = 0;
>>>>>> -
>>>>>> - addr = find_ibft_region(&size);
>>>>>> -
>>>>>> - if (size)
>>>>>> - memblock_reserve(addr, size);
>>>>>> -}
>>>>>> -
>>>>>> static bool __init snb_gfx_workaround_needed(void)
>>>>>> {
>>>>>> #ifdef CONFIG_PCI
>>>>>> @@ -1032,6 +1022,12 @@ void __init setup_arch(char **cmdline_p)
>>>>>> */
>>>>>> find_smp_config();
>>>>>> + /*
>>>>>> + * Initialize the ACPI boot-time table parser.
>>>>>> + */
>>>>>> + if (acpi_table_init())
>>>>>> + disable_acpi();
>>>>>> +
>>>>>> reserve_ibft_region();
>>>>>> early_alloc_pgt_buf();
>>>>>> diff --git a/drivers/firmware/iscsi_ibft_find.c
>>>>>> b/drivers/firmware/iscsi_ibft_find.c
>>>>>> index 64bb94523281..01be513843d6 100644
>>>>>> --- a/drivers/firmware/iscsi_ibft_find.c
>>>>>> +++ b/drivers/firmware/iscsi_ibft_find.c
>>>>>> @@ -47,7 +47,25 @@ static const struct {
>>>>>> #define VGA_MEM 0xA0000 /* VGA buffer */
>>>>>> #define VGA_SIZE 0x20000 /* 128kB */
>>>>>> -static int __init find_ibft_in_mem(void)
>>>>>> +static void __init *acpi_find_ibft_region(void)
>>>>>> +{
>>>>>> + int i;
>>>>>> + struct acpi_table_header *table = NULL;
>>>>>> + acpi_status status;
>>>>>> +
>>>>>> + if (acpi_disabled)
>>>>>> + return NULL;
>>>>>> +
>>>>>> + for (i = 0; i < ARRAY_SIZE(ibft_signs) && !ibft_addr; i++) {
>>>>>> + status = acpi_get_table(ibft_signs[i].sign, 0, &table);
>>>>>> + if (ACPI_SUCCESS(status))
>>>>>> + return table;
>>>>>> + }
>>>>>> +
>>>>>> + return NULL;
>>>>>> +}
>>>>>> +
>>>>>> +static void __init *find_ibft_in_mem(void)
>>>>>> {
>>>>>> unsigned long pos;
>>>>>> unsigned int len = 0;
>>>>>> @@ -70,35 +88,44 @@ static int __init find_ibft_in_mem(void)
>>>>>> /* if the length of the table extends past 1M,
>>>>>> * the table cannot be valid. */
>>>>>> if (pos + len <= (IBFT_END-1)) {
>>>>>> - ibft_addr = (struct acpi_table_ibft *)virt;
>>>>>> pr_info("iBFT found at 0x%lx.\n", pos);
>>>>>> - goto done;
>>>>>> + return virt;
>>>>>> }
>>>>>> }
>>>>>> }
>>>>>> }
>>>>>> -done:
>>>>>> - return len;
>>>>>> +
>>>>>> + return NULL;
>>>>>> }
>>>>>> +
>>>>>> +static void __init *find_ibft(void)
>>>>>> +{
>>>>>> + /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
>>>>>> + * only use ACPI for this */
>>>>>> + if (!efi_enabled(EFI_BOOT))
>>>>>> + return find_ibft_in_mem();
>>>>>> + else
>>>>>> + return acpi_find_ibft_region();
>>>>>> +}
>>>>>> +
>>>>>> /*
>>>>>> * Routine used to find the iSCSI Boot Format Table. The logical
>>>>>> * kernel address is set in the ibft_addr global variable.
>>>>>> */
>>>>>> -unsigned long __init find_ibft_region(unsigned long *sizep)
>>>>>> +void __init reserve_ibft_region(void)
>>>>>> {
>>>>>> - ibft_addr = NULL;
>>>>>> + struct acpi_table_ibft *table;
>>>>>> + unsigned long size;
>>>>>> - /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
>>>>>> - * only use ACPI for this */
>>>>>> + table = find_ibft();
>>>>>> + if (!table)
>>>>>> + return;
>>>>>> - if (!efi_enabled(EFI_BOOT))
>>>>>> - find_ibft_in_mem();
>>>>>> -
>>>>>> - if (ibft_addr) {
>>>>>> - *sizep = PAGE_ALIGN(ibft_addr->header.length);
>>>>>> - return (u64)virt_to_phys(ibft_addr);
>>>>>> - }
>>>>>> + size = PAGE_ALIGN(table->header.length);
>>>>>> + memblock_reserve(virt_to_phys(table), size);
>>>>>> - *sizep = 0;
>>>>>> - return 0;
>>>>>> + if (efi_enabled(EFI_BOOT))
>>>>>> + acpi_put_table(&table->header);
>>>>>> + else
>>>>>> + ibft_addr = table;
>>>>>> }
>>>>>> diff --git a/include/linux/iscsi_ibft.h b/include/linux/iscsi_ibft.h
>>>>>> index b7b45ca82bea..da813c891990 100644
>>>>>> --- a/include/linux/iscsi_ibft.h
>>>>>> +++ b/include/linux/iscsi_ibft.h
>>>>>> @@ -26,13 +26,9 @@ extern struct acpi_table_ibft *ibft_addr;
>>>>>> * mapped address is set in the ibft_addr variable.
>>>>>> */
>>>>>> #ifdef CONFIG_ISCSI_IBFT_FIND
>>>>>> -unsigned long find_ibft_region(unsigned long *sizep);
>>>>>> +void reserve_ibft_region(void);
>>>>>> #else
>>>>>> -static inline unsigned long find_ibft_region(unsigned long *sizep)
>>>>>> -{
>>>>>> - *sizep = 0;
>>>>>> - return 0;
>>>>>> -}
>>>>>> +static inline void reserve_ibft_region(void) {}
>>>>>> #endif
>>>>>> #endif /* ISCSI_IBFT_H */
>>>>> Still no luck Mike,
>>>>>
>>>>> We're back to the original problem where the only thing that
>>>>> worked was to
>>>>> run "SetPageReserved(page)" before calling "kmap(page)". The page
>>>>> is being
>>>>> "freed" before ibft_init() is called as a result of the recent
>>>>> buddy page
>>>>> freeing changes.
>>>> I keep missing some little details each time :(
>>> No worries. Thanks for all your help. Does this patch go on top of your
>>> previous patch or is it standalone?
>> This is standalone.
>>> George
>>>> Ok, let's try from the different angle.
>>>>
>>>> diff --git a/drivers/acpi/acpica/tbutils.c
>>>> b/drivers/acpi/acpica/tbutils.c
>>>> index 4b9b329a5a92..ec43e1447336 100644
>>>> --- a/drivers/acpi/acpica/tbutils.c
>>>> +++ b/drivers/acpi/acpica/tbutils.c
>>>> @@ -7,6 +7,8 @@
>>>> *
>>>> *****************************************************************************/
>>>> +#include <linux/memblock.h>
>>>> +
>>>> #include <acpi/acpi.h>
>>>> #include "accommon.h"
>>>> #include "actables.h"
>>>> @@ -339,6 +341,21 @@ acpi_tb_parse_root_table(acpi_physical_address
>>>> rsdp_address)
>>>> acpi_tb_parse_fadt();
>>>> }
>>>> + if (ACPI_SUCCESS(status) &&
>>>> + ACPI_COMPARE_NAMESEG(&acpi_gbl_root_table_list.
>>>> + tables[table_index].signature,
>>>> + ACPI_SIG_IBFT)) {
>>>> + struct acpi_table_header *ibft;
>>>> + struct acpi_table_desc *desc;
>>>> +
>>>> + desc = &acpi_gbl_root_table_list.tables[table_index];
>>>> + status = acpi_tb_get_table(desc, &ibft);
>>>> + if (ACPI_SUCCESS(status)) {
>>>> + memblock_reserve(address, ibft->length);
>>>> + acpi_tb_put_table(desc);
>>>> +
>>>> + }
>>>> +
>>>> next_table:
>>>> table_entry += table_entry_size;
>>>>
>>>>
> Applied just your latest patch, but same failure.
>
> I thought there was an earlier comment (which I can't find now) that
> stated that memblock_reserve() wouldn't reserve the page, which is
> what's needed here.
Mike,
Here was David's explanation of what he thinks is going on (or should be
going on) from a few days ago:
QUOTE...
I assume that acpi_map()/acpi_unmap() map some firmware blob that is
provided via firmware/bios/... to us.
should_use_kmap() tells us whether
a) we have a "struct page" and should kmap() that one
b) we don't have a "struct page" and should ioremap.
As it is a blob, the firmware should always reserve that memory region
via memblock (e.g., memblock_reserve()), such that we either
1) don't create a memmap ("struct page") at all (-> case b) )
2) if we have to create e memmap, we mark the page PG_reserved and
*never* expose it to the buddy (-> case a) )
Are you telling me that in this case we might have a memmap for the HW
blob that is *not* PG_reserved? In that case it most probably got
exposed to the buddy where it can happily get allocated/freed.
The latent BUG would be that that blob gets exposed to the system like
ordinary RAM, and not reserved via memblock early during boot. Assuming
that blob has a low physical address, with my patch it will get
allocated/used a lot earlier - which would mean we trigger this latent
BUG now more easily.
...END_QUOTE
Your most recent patch has added the memblock_reserve(), but it's still
missing the PG_reserved setting.
Thanks,
George
>
> [ 30.308229] iBFT detected..
> [ 30.308796]
> ==================================================================
> [ 30.308890] BUG: KASAN: use-after-free in ibft_init+0x134/0xc33
> [ 30.308890] Read of size 4 at addr ffff8880be453004 by task
> swapper/0/1
> [ 30.308890]
> [ 30.308890] CPU: 1 PID: 1 Comm: swapper/0 Not tainted
> 5.11.0-f9593a0 #12
> [ 30.308890] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 0.0.0 02/06/2015
> [ 30.308890] Call Trace:
> [ 30.308890] dump_stack+0xdb/0x120
> [ 30.308890] ? ibft_init+0x134/0xc33
> [ 30.308890] print_address_description.constprop.7+0x41/0x60
> [ 30.308890] ? ibft_init+0x134/0xc33
> [ 30.308890] ? ibft_init+0x134/0xc33
> [ 30.308890] kasan_report.cold.10+0x78/0xd1
> [ 30.308890] ? ibft_init+0x134/0xc33
> [ 30.308890] __asan_report_load_n_noabort+0xf/0x20
> [ 30.308890] ibft_init+0x134/0xc33
> [ 30.308890] ? write_comp_data+0x2f/0x90
> [ 30.308890] ? ibft_check_initiator_for+0x159/0x159
> [ 30.308890] ? write_comp_data+0x2f/0x90
> [ 30.308890] ? ibft_check_initiator_for+0x159/0x159
> [ 30.308890] do_one_initcall+0xc4/0x3e0
> [ 30.308890] ? perf_trace_initcall_level+0x3e0/0x3e0
> [ 30.308890] ? unpoison_range+0x14/0x40
> [ 30.308890] ? ____kasan_kmalloc.constprop.5+0x8f/0xc0
> [ 30.308890] ? kernel_init_freeable+0x420/0x652
> [ 30.308890] ? __kasan_kmalloc+0x9/0x10
> [ 30.308890] ? __sanitizer_cov_trace_pc+0x21/0x50
> [ 30.308890] kernel_init_freeable+0x596/0x652
> [ 30.308890] ? console_on_rootfs+0x7d/0x7d
> [ 30.308890] ? __sanitizer_cov_trace_pc+0x21/0x50
> [ 30.308890] ? rest_init+0xf0/0xf0
> [ 30.308890] kernel_init+0x16/0x1d0
> [ 30.308890] ? rest_init+0xf0/0xf0
> [ 30.308890] ret_from_fork+0x22/0x30
> [ 30.308890]
> [ 30.308890] The buggy address belongs to the page:
> [ 30.308890] page:0000000001b7b17c refcount:0 mapcount:0
> mapping:0000000000000000 index:0x1 pfn:0xbe453
> [ 30.308890] flags: 0xfffffc0000000()
> [ 30.308890] raw: 000fffffc0000000 ffffea0002ef9788 ffffea0002f91488
> 0000000000000000
> [ 30.308890] raw: 0000000000000001 0000000000000000 00000000ffffffff
> 0000000000000000
> [ 30.308890] page dumped because: kasan: bad access detected
> [ 30.308890] page_owner tracks the page as freed
> [ 30.308890] page last allocated via order 0, migratetype Movable,
> gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 204, ts
> 28121288605
> [ 30.308890] prep_new_page+0xfb/0x140
> [ 30.308890] get_page_from_freelist+0x3503/0x5730
> [ 30.308890] __alloc_pages_nodemask+0x2d8/0x650
> [ 30.308890] alloc_pages_vma+0xe2/0x560
> [ 30.308890] __handle_mm_fault+0x930/0x26c0
> [ 30.308890] handle_mm_fault+0x1f9/0x810
> [ 30.308890] do_user_addr_fault+0x6f7/0xca0
> [ 30.308890] exc_page_fault+0xaf/0x1a0
> [ 30.308890] asm_exc_page_fault+0x1e/0x30
> [ 30.308890] page last free stack trace:
> [ 30.308890] free_pcp_prepare+0x122/0x290
> [ 30.308890] free_unref_page_list+0xe6/0x490
> [ 30.308890] release_pages+0x2ed/0x1270
> [ 30.308890] free_pages_and_swap_cache+0x245/0x2e0
> [ 30.308890] tlb_flush_mmu+0x11e/0x680
> [ 30.308890] tlb_finish_mmu+0xa6/0x3e0
> [ 30.308890] exit_mmap+0x2b3/0x540
> [ 30.308890] mmput+0x11d/0x450
> [ 30.308890] do_exit+0xaa6/0x2d40
> [ 30.308890] do_group_exit+0x128/0x340
> [ 30.308890] __x64_sys_exit_group+0x43/0x50
> [ 30.308890] do_syscall_64+0x37/0x50
> [ 30.308890] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 30.308890]
> [ 30.308890] Memory state around the buggy address:
> [ 30.308890] ffff8880be452f00: ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff
> [ 30.308890] ffff8880be452f80: ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff
> [ 30.308890] >ffff8880be453000: ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff
> [ 30.308890] ^
> [ 30.308890] ffff8880be453080: ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff
> [ 30.308890] ffff8880be453100: ff ff ff ff ff ff ff ff ff ff ff ff
> ff ff ff ff
> [ 30.308890]
> ==================================================================
>
> George
>
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