On Wed, Jan 27, 2021 at 9:01 PM George Kennedy <george.kenn...@oracle.com> wrote: > > 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.w...@oracle.com> 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?
Most of these files are disabled because they cause recursion in instrumentation, or execute too early in bootstrap process (before kasan_init). Somehow the table pointer in ibft_init points to a freed page. I tracked it down to here: https://elixir.bootlin.com/linux/v5.4.17/source/drivers/acpi/acpica/tbutils.c#L399 but I can't find where this table_desc->pointer comes from. Perhaps it uses some allocation method that's not supported by KASAN? However, it's the only such case that I've seen, so it's a bit weird. Could it use something like memblock_alloc? Or maybe that page was in fact freed?... Too bad KASAN does not print free stack for pages, maybe it's not too hard to do if CONFIG_PAGE_OWNER is enabled... > Thank you, > George > > > Signed-off-by: George Kennedy <george.kenn...@oracle.com> > --- > 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 > >
