Re: ppc64el kernel access of bad area (ext4_htree_store_dirent->rb_insert_color)

From: Dmitry Vyukov <dvyukov@google.com>
To: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>
Cc: Eric Biggers <ebiggers3@gmail.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	syzbot 
	<bot+eb13811afcefe99cfe45081054e7883f569f949d@syzkaller.appspotmail.com>,
	linux-ext4@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	"Theodore Ts'o" <tytso@mit.edu>
Subject: Re: ppc64el kernel access of bad area (ext4_htree_store_dirent->rb_insert_color)
Date: Mon, 9 Dec 2019 14:46:27 +0100	[thread overview]
Message-ID: <CACT4Y+YtpOZ1c0QV4-q_b-CrGMGRALwoFTNPgxZuUC9S9J3gfA@mail.gmail.com> (raw)
In-Reply-To: <20191209132914.907306-1-rafaeldtinoco@ubuntu.com>

On Mon, Dec 9, 2019 at 2:29 PM Rafael David Tinoco
<rafaeldtinoco@ubuntu.com> wrote:
>
> It looks like the same stacktrace that was reported in this thread. This has
> been reported to ppc64el AND we got a reproducer (ocfs2-tools autopkgtests).
>
> [ 85.605850] Faulting instruction address: 0xc000000000e81168
> [ 85.605901] Oops: Kernel access of bad area, sig: 11 [#1]
> [ 85.605970] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
> [ 85.606029] Modules linked in: ocfs2 quota_tree ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue iptable_mangle xt_TCPMSS xt_tcpudp bpfilter dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua vmx_crypto crct10dif_vpmsum sch_fq_codel ip_tables x_tables autofs4 btrfs xor zstd_compress raid6_pq libcrc32c crc32c_vpmsum virtio_net virtio_blk net_failover failover
> [ 85.606291] CPU: 0 PID: 1 Comm: systemd Not tainted 5.3.0-18-generic #19-Ubuntu
> [ 85.606350] NIP: c000000000e81168 LR: c00000000054f240 CTR: 0000000000000000
> [ 85.606410] REGS: c00000005a3e3700 TRAP: 0300 Not tainted (5.3.0-18-generic)
> [ 85.606469] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 28024448 XER: 00000000
> [ 85.606531] CFAR: 0000701f9806f638 DAR: 0000000001744098 DSISR: 40000000 IRQMASK: 0
> [ 85.606531] GPR00: 0000000000007374 c00000005a3e3990 c0000000019c9100 c00000004fe462a8
> [ 85.606531] GPR04: c00000005856d840 000000000000000e 0000000074656772 c00000004fe4a568
> [ 85.606531] GPR08: 0000000000000000 c000000058568004 0000000001744090 0000000000000000
> [ 85.606531] GPR12: 00000000e8086002 c000000001d60000 00007fffddd522d0 0000000000000000
> [ 85.606531] GPR16: 0000000000000000 0000000000000000 0000000000000000 c00000000755e07c
> [ 85.606531] GPR20: c0000000598caca8 c00000005a3e3a58 0000000000000000 c000000058292f00
> [ 85.606531] GPR24: c000000000eea710 0000000000000000 c00000005856d840 c00000000755e074
> [ 85.606531] GPR28: 000000006518907d c00000005a3e3a68 c00000004fe4b160 00000000027c47b6
> [ 85.607079] NIP [c000000000e81168] rb_insert_color+0x18/0x1c0
> [ 85.607137] LR [c00000000054f240] ext4_htree_store_dirent+0x140/0x1c0
> [ 85.607186] Call Trace:
> [ 85.607208] [c00000005a3e3990] [c00000000054f158] ext4_htree_store_dirent+0x58/0x1c0 (unreliable)
> [ 85.607279] [c00000005a3e39e0] [c000000000594cd8] htree_dirblock_to_tree+0x1b8/0x380
> [ 85.607340] [c00000005a3e3b00] [c0000000005962c0] ext4_htree_fill_tree+0xc0/0x3f0
> [ 85.607401] [c00000005a3e3c00] [c00000000054ebe4] ext4_readdir+0x814/0xce0
> [ 85.607459] [c00000005a3e3d40] [c000000000472d6c] iterate_dir+0x1fc/0x280
> [ 85.607511] [c00000005a3e3d90] [c0000000004746f0] ksys_getdents64+0xa0/0x1f0
> [ 85.607572] [c00000005a3e3e00] [c000000000474868] sys_getdents64+0x28/0x130
> [ 85.607622] [c00000005a3e3e20] [c00000000000b388] system_call+0x5c/0x70
> [ 85.607672] Instruction dump:
> [ 85.607703] 4082ffe8 4e800020 38600000 4e800020 60000000 60000000 e9230000 2c290000
> [ 85.607764] 4182018c e9490000 71480001 4c820020 <e90a0008> 7c284840 2fa80000 4182006c
> [ 85.607827] ---[ end trace cfc53af0f8d62cef ]---
> [ 85.610600]
> [ 86.611522] BUG: Unable to handle kernel data access at 0xc000030058567eff
> [ 86.611604] Faulting instruction address: 0xc000000000403aa8
> [ 86.611656] Oops: Kernel access of bad area, sig: 11 [#2]
> [ 86.611697] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
> [ 86.611748] Modules linked in: ocfs2 quota_tr
>
> Thread from beginning 2018, so I guess this issue is pretty intermittent but
> might exist, and, perhaps, its related to specific arches/machines ?

FTR, here is the original thread/bug (at least my email client did not
thread them together):
https://groups.google.com/g/syzkaller-bugs/c/YBhhSkrImIM/m/3HMv_dFUCwAJ
https://syzkaller.appspot.com/bug?extid=eb13811afcefe99cfe45081054e7883f569f949d