Re: [PATCH 1/1] iscsi_ibft: KASAN false positive failure occurs in ibft_init()
From: George Kennedy
Date: Wed Jan 27 2021 - 15:48:41 EST
Hi Dmitry,
On 1/27/2021 1:48 PM, Dmitry Vyukov wrote:
> On Wed, Jan 27, 2021 at 7:44 PM Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx> wrote:
>> On Tue, Jan 26, 2021 at 01:03:21PM -0500, George Kennedy wrote:
>>> During boot of kernel with CONFIG_KASAN the following KASAN false
>>> positive failure will occur when ibft_init() reads the
>>> ACPI iBFT table: BUG: KASAN: use-after-free in ibft_init
>>>
>>> The ACPI iBFT table is not allocated, and the iscsi driver uses
>>> a pointer to it to calculate checksum, etc. KASAN complains
>>> about this pointer with use-after-free, which this is not.
>>>
>> Andrey, Alexander, Dmitry,
>>
>> I think this is the right way for this, but was wondering if you have
>> other suggestions?
>>
>> Thanks!
> Hi George, Konrad,
>
> Please provide a sample KASAN report and kernel version to match line numbers.
5.4.17-2102.200.0.0.20210106_0000
[ 24.413536] iBFT detected.
[ 24.414074]
==================================================================
[ 24.407342] BUG: KASAN: use-after-free in ibft_init+0x134/0xb8b
[ 24.407342] Read of size 4 at addr ffff8880be452004 by task swapper/0/1
[ 24.407342]
[ 24.407342] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.4.17-2102.200.0.0.20210106_0000.syzk #1
[ 24.407342] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
[ 24.407342] Call Trace:
[ 24.407342] dump_stack+0xd4/0x119
[ 24.407342] ? ibft_init+0x134/0xb8b
[ 24.407342] print_address_description.constprop.6+0x20/0x220
[ 24.407342] ? ibft_init+0x134/0xb8b
[ 24.407342] ? ibft_init+0x134/0xb8b
[ 24.407342] __kasan_report.cold.9+0x37/0x77
[ 24.407342] ? ibft_init+0x134/0xb8b
[ 24.407342] kasan_report+0x14/0x1b
[ 24.407342] __asan_report_load_n_noabort+0xf/0x11
[ 24.407342] ibft_init+0x134/0xb8b
[ 24.407342] ? dmi_sysfs_init+0x1a5/0x1a5
[ 24.407342] ? dmi_walk+0x72/0x89
[ 24.407342] ? ibft_check_initiator_for+0x159/0x159
[ 24.407342] ? rvt_init_port+0x110/0x101
[ 24.407342] ? ibft_check_initiator_for+0x159/0x159
[ 24.407342] do_one_initcall+0xc3/0x44d
[ 24.407342] ? perf_trace_initcall_level+0x410/0x405
[ 24.407342] kernel_init_freeable+0x551/0x673
[ 24.407342] ? start_kernel+0x94b/0x94b
[ 24.407342] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x1c
[ 24.407342] ? __kasan_check_write+0x14/0x16
[ 24.407342] ? rest_init+0xe6/0xe6
[ 24.407342] kernel_init+0x16/0x1bd
[ 24.407342] ? rest_init+0xe6/0xe6
[ 24.407342] ret_from_fork+0x2b/0x36
[ 24.407342]
[ 24.407342] The buggy address belongs to the page:
[ 24.407342] page:ffffea0002f91480 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1
[ 24.407342] flags: 0xfffffc0000000()
[ 24.407342] raw: 000fffffc0000000 ffffea0002fca588 ffffea0002fb1a88 0000000000000000
[ 24.407342] raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
[ 24.407342] page dumped because: kasan: bad access detected
[ 24.407342]
[ 24.407342] Memory state around the buggy address:
[ 24.407342] ffff8880be451f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 24.407342] ffff8880be451f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 24.407342] >ffff8880be452000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 24.407342] ^
[ 24.407342] ffff8880be452080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 24.407342] ffff8880be452100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 24.407342]
==================================================================
[ 24.407342] Disabling lock debugging due to kernel taint
[ 24.451021] Kernel panic - not syncing: panic_on_warn set ...
[ 24.452002] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G B 5.4.17-2102.200.0.0.20210106_0000.syzk #1
[ 24.452002] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
[ 24.452002] Call Trace:
[ 24.452002] dump_stack+0xd4/0x119
[ 24.452002] ? ibft_init+0x102/0xb8b
[ 24.452002] panic+0x28f/0x6e0
[ 24.452002] ? __warn_printk+0xe0/0xe0
[ 24.452002] ? ibft_init+0x134/0xb8b
[ 24.452002] ? add_taint+0x68/0xb3
[ 24.452002] ? add_taint+0x68/0xb3
[ 24.452002] ? ibft_init+0x134/0xb8b
[ 24.452002] ? ibft_init+0x134/0xb8b
[ 24.452002] end_report+0x4c/0x54
[ 24.452002] __kasan_report.cold.9+0x55/0x77
[ 24.452002] ? ibft_init+0x134/0xb8b
[ 24.452002] kasan_report+0x14/0x1b
[ 24.452002] __asan_report_load_n_noabort+0xf/0x11
[ 24.452002] ibft_init+0x134/0xb8b
[ 24.452002] ? dmi_sysfs_init+0x1a5/0x1a5
[ 24.452002] ? dmi_walk+0x72/0x89
[ 24.452002] ? ibft_check_initiator_for+0x159/0x159
[ 24.452002] ? rvt_init_port+0x110/0x101
[ 24.452002] ? ibft_check_initiator_for+0x159/0x159
[ 24.452002] do_one_initcall+0xc3/0x44d
[ 24.452002] ? perf_trace_initcall_level+0x410/0x405
[ 24.452002] kernel_init_freeable+0x551/0x673
[ 24.452002] ? start_kernel+0x94b/0x94b
[ 24.452002] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x1c
[ 24.452002] ? __kasan_check_write+0x14/0x16
[ 24.452002] ? rest_init+0xe6/0xe6
[ 24.452002] kernel_init+0x16/0x1bd
[ 24.452002] ? rest_init+0xe6/0xe6
[ 24.452002] ret_from_fork+0x2b/0x36
[ 24.452002] Dumping ftrace buffer:
[ 24.452002] ---------------------------------
[ 24.452002] swapper/-1 1.... 24564337us : rdmaip_init: 2924: rdmaip_init: Active Bonding is DISABLED
[ 24.452002] ---------------------------------
[ 24.452002] Kernel Offset: disabled
[ 24.452002] Rebooting in 1 seconds..
> Why does KASAN think the address is freed? For that to happen that
> memory should have been freed. I don't remember any similar false
> positives from KASAN, so this looks a bit suspicious.
I'm not sure why KASAN thinks the address is freed. There are other modules where KASAN/KCOV is disabled on boot.
Could this be for a similar reason?
Thank you,
George
>>> Signed-off-by: George Kennedy <george.kennedy@xxxxxxxxxx>
>>> ---
>>> drivers/firmware/Makefile | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
>>> index 5e013b6..30ddab5 100644
>>> --- a/drivers/firmware/Makefile
>>> +++ b/drivers/firmware/Makefile
>>> @@ -14,6 +14,9 @@ obj-$(CONFIG_INTEL_STRATIX10_SERVICE) += stratix10-svc.o
>>> obj-$(CONFIG_INTEL_STRATIX10_RSU) += stratix10-rsu.o
>>> obj-$(CONFIG_ISCSI_IBFT_FIND) += iscsi_ibft_find.o
>>> obj-$(CONFIG_ISCSI_IBFT) += iscsi_ibft.o
>>> +KASAN_SANITIZE_iscsi_ibft.o := n
>>> +KCOV_INSTRUMENT_iscsi_ibft.o := n
>>> +
>>> obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
>>> obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
>>> obj-$(CONFIG_FW_CFG_SYSFS) += qemu_fw_cfg.o
>>> --
>>> 1.8.3.1
>>>