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Message-ID: <20181005130506.GA5972@hc>
Date: Fri, 5 Oct 2018 13:05:24 +0000
From: Jan Glauber <Jan.Glauber@...ium.com>
To: Dmitry Vyukov <dvyukov@...gle.com>
CC: Theodore Ts'o <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
"kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>
Subject: Re: KASAN: use-after-scope in ext4_group_desc_csum
On Fri, Oct 05, 2018 at 01:13:52PM +0200, Dmitry Vyukov wrote:
> On Fri, Oct 5, 2018 at 12:16 PM, Jan Glauber <Jan.Glauber@...ium.com> wrote:
> > Hi,
> >
> > I'm getting below warning when I enable CONFIG_KASAN_EXTRA=y on a arm64 ThunderX2 system.
> > As far as I can tell this is present since KASAN_EXTRA was introduced (4.16).
> >
> > [ 64.547333] ==================================================================
> > [ 64.561933] BUG: KASAN: use-after-scope in ext4_es_lookup_extent+0x130/0x980
> > [ 64.576105] Write of size 4 at addr ffff80222d81f0ec by task exe/4075
> >
> > [ 64.592044] CPU: 102 PID: 4075 Comm: exe Not tainted 4.19.0-rc6-jang+ #29
> > [ 64.605690] Hardware name: To be filled by O.E.M. Saber/To be filled by O.E.M., BIOS 0ACKL018 03/30/2018
> > [ 64.624750] Call trace:
> > [ 64.629666] dump_backtrace+0x0/0x360
> > [ 64.637024] show_stack+0x24/0x30
> > [ 64.643687] dump_stack+0x12c/0x1b4
> > [ 64.650699] print_address_description+0x68/0x2c8
> > [ 64.660152] kasan_report+0x130/0x300
> > [ 64.667509] __asan_store4+0x84/0xa8
> > [ 64.674693] ext4_es_lookup_extent+0x130/0x980
> > [ 64.683623] ext4_map_blocks+0xe0/0x990
> > [ 64.691330] _ext4_get_block+0x130/0x2b8
> > [ 64.699211] ext4_get_block+0x40/0x50
> > [ 64.706571] generic_block_bmap+0x104/0x178
> > [ 64.714977] ext4_bmap+0xc4/0x198
> > [ 64.721636] bmap+0x54/0x70
> > [ 64.727250] jbd2_journal_init_inode+0x2c/0x208
> > [ 64.736355] ext4_fill_super+0x5080/0x5c90
> > [ 64.744587] mount_bdev+0x1e0/0x228
> > [ 64.751597] ext4_mount+0x44/0x58
> > [ 64.758255] mount_fs+0x58/0x1b8
> > [ 64.764740] vfs_kern_mount.part.2+0xc0/0x2a8
> > [ 64.773495] do_mount+0x7a8/0x13e8
> > [ 64.780327] ksys_mount+0x9c/0x110
> > [ 64.787160] __arm64_sys_mount+0x70/0x88
> > [ 64.795043] el0_svc_handler+0xac/0x150
> > [ 64.802749] el0_svc+0x8/0xc
> >
> > [ 64.811521] The buggy address belongs to the page:
> > [ 64.821149] page:ffff7e0088b607c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
> > [ 64.837249] flags: 0x1ffff00000000000()
> > [ 64.844959] raw: 1ffff00000000000 ffff7e0088b607c8 ffff7e0088b607c8 0000000000000000
> > [ 64.860527] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> > [ 64.876093] page dumped because: kasan: bad access detected
> >
> > [ 64.890278] Memory state around the buggy address:
> > [ 64.899907] ffff80222d81ef80: f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2
> > [ 64.914426] ffff80222d81f000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > [ 64.928945] >ffff80222d81f080: f8 f8 f8 f8 f8 f8 f1 f1 f1 f1 f8 f8 f8 f8 00 f2
> > [ 64.943463] ^
> > [ 64.956759] ffff80222d81f100: f2 f2 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > [ 64.971278] ffff80222d81f180: f8 f8 f8 f8 f1 f1 f1 f1 00 00 00 f2 f8 f8 f8 f8
> > [ 64.985795] ==================================================================
> > [ 65.000312] Disabling lock debugging due to kernel taint
> > [ 65.037509] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null)
> >
> > I'm not seeing any issues like filesystem corruption or misbehaviour that could be related
> > the warning.
> >
> > Is this a false positive? Any thoughts?
>
>
> Hi Jan,
>
> What kernel commit are you using? Kernel config? Compiler?
> Please symbolize the report with scripts/decode_stacktrace.sh in
> kernel tree or https://github.com/google/sanitizers/blob/master/address-sanitizer/tools/kasan_symbolize.py
Hi Dmitry,
I can reproduce this since 4.16, the report above is from 4.19-rc6.
Kernel config:
https://paste.debian.net/1046031/
Compiler is the stock gcc from Ubuntu 18.04.1:
gcc version 7.3.0 (Ubuntu/Linaro 7.3.0-27ubuntu1~18.04)
Here is the decoded stacktrace:
[ 64.547333] ==================================================================
[ 64.561933] BUG: KASAN: use-after-scope in ext4_es_lookup_extent (fs/ext4/extents_status.c:795)
[ 64.576105] Write of size 4 at addr ffff80222d81f0ec by task exe/4075
[ 64.592044] CPU: 102 PID: 4075 Comm: exe Not tainted 4.19.0-rc6-jang+ #29
[ 64.605690] Hardware name: To be filled by O.E.M. Saber/To be filled by O.E.M., BIOS 0ACKL018 03/30/2018
[ 64.624750] Call trace:
[ 64.629666] dump_backtrace (arch/arm64/kernel/traps.c:102)
[ 64.637024] show_stack (arch/arm64/kernel/traps.c:154)
[ 64.643687] dump_stack (lib/dump_stack.c:115)
[ 64.650699] print_address_description (mm/kasan/report.c:257)
[ 64.660152] kasan_report (mm/kasan/report.c:355 mm/kasan/report.c:412)
[ 64.667509] __asan_store4 (mm/kasan/kasan.c:699)
[ 64.674693] ext4_es_lookup_extent (fs/ext4/extents_status.c:795)
[ 64.683623] ext4_map_blocks (fs/ext4/inode.c:526)
[ 64.691330] _ext4_get_block (fs/ext4/inode.c:783 (discriminator 3))
[ 64.699211] ext4_get_block (fs/ext4/inode.c:802)
[ 64.706571] generic_block_bmap (fs/buffer.c:2969)
[ 64.714977] ext4_bmap (fs/ext4/inode.c:3314)
[ 64.721636] bmap (fs/inode.c:1595)
[ 64.727250] jbd2_journal_init_inode (fs/jbd2/journal.c:1257)
[ 64.736355] ext4_fill_super (fs/ext4/super.c:4615 fs/ext4/super.c:4770 fs/ext4/super.c:4157)
[ 64.744587] mount_bdev (fs/super.c:1158)
[ 64.751597] ext4_mount (fs/ext4/super.c:5869)
[ 64.758255] mount_fs (fs/super.c:1261)
[ 64.764740] vfs_kern_mount.part.2 (fs/namespace.c:961)
[ 64.773495] do_mount (fs/namespace.c:2454 fs/namespace.c:2457 fs/namespace.c:2787)
[ 64.780327] ksys_mount (fs/namespace.c:3003)
[ 64.787160] __arm64_sys_mount (fs/namespace.c:3014)
[ 64.795043] el0_svc_handler (arch/arm64/kernel/syscall.c:36 arch/arm64/kernel/syscall.c:48 arch/arm64/kernel/syscall.c:84 arch/arm64/kernel/syscall.c:130)
[ 64.802749] el0_svc (arch/arm64/kernel/entry.S:918)
[ 64.811521] The buggy address belongs to the page:
[ 64.821149] page:ffff7e0088b607c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
[ 64.837249] flags: 0x1ffff00000000000()
[ 64.844959] raw: 1ffff00000000000 ffff7e0088b607c8 ffff7e0088b607c8 0000000000000000
[ 64.860527] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[ 64.876093] page dumped because: kasan: bad access detected
[ 64.890278] Memory state around the buggy address:
[ 64.899907] ffff80222d81ef80: f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2
[ 64.914426] ffff80222d81f000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
[ 64.928945] >ffff80222d81f080: f8 f8 f8 f8 f8 f8 f1 f1 f1 f1 f8 f8 f8 f8 00 f2
[ 64.943463] ^
[ 64.956759] ffff80222d81f100: f2 f2 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
[ 64.971278] ffff80222d81f180: f8 f8 f8 f8 f1 f1 f1 f1 00 00 00 f2 f8 f8 f8 f8
[ 64.985795] ==================================================================
[ 65.000312] Disabling lock debugging due to kernel taint
[ 65.037509] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null)
--Jan
View attachment "config-4.19-rc6" of type "text/plain" (96491 bytes)
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