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Date: Mon, 28 Mar 2016 00:43:39 -0400
From: Theodore Ts'o <tytso@....edu>
To: jack@...e.cz
Cc: linux-ext4@...r.kernel.org
Subject: GETNEXTQUOTA causes kernel crash if quota not enabled
Hi Jan, this looks like a recent change that just landed in the quota
tree. The crash is in dquot_get_next_id() because
sb_dqopt(sb)->ops[0] is NULL.
This looks like it was introduced in a fairly recent commit:
be6257b251ce ("quota: Add support for ->get_nextdqblk() for VFS
quota").
Please see reproduction below. It can also be easily reproduced using
"kvm-xfstests -c encrypt generic/244")
- Ted
root@...-xfstests:~# mke2fs -t ext4 -Fq /dev/vdc
/dev/vdc contains a ext4 file system
last mounted on Mon Mar 28 00:35:45 2016
root@...-xfstests:~# mount /vdc
root@...-xfstests:~# dmesg -n 7
root@...-xfstests:~# ./xfstests/src/test-nextquota -i 0 -u -d /dev/vdc
[ 29.881729] ------------[ cut here ]------------
[ 29.882608] WARNING: CPU: 0 PID: 2634 at /usr/projects/linux/ext4/fs/quota/dquot.c:2051 dquot_get_next_id+0x40/0xc2
[ 29.884416] Modules linked in:
[ 29.884832] CPU: 0 PID: 2634 Comm: test-nextquota Tainted: G W 4.5.0-11280-g3d43bcf-dirty #516
[ 29.886028] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 29.886742] 00000000 00000246 f34e3dc8 c13da85f 00000000 c11b86c9 f34e3de0 c10856e0
[ 29.887777] 00000803 f61f7800 f34e3e2c f61f78cc f34e3df4 c1085772 00000009 00000000
[ 29.888809] 00000000 f34e3e08 c11b86c9 c11b8689 f34e3e7c f61f7800 f34e3e20 c11ba297
[ 29.889861] Call Trace:
[ 29.890166] [<c13da85f>] dump_stack+0x72/0xa3
[ 29.890760] [<c11b86c9>] ? dquot_get_next_id+0x40/0xc2
[ 29.891402] [<c10856e0>] __warn+0xbc/0xd3
[ 29.891916] [<c1085772>] warn_slowpath_null+0x16/0x1b
[ 29.892552] [<c11b86c9>] dquot_get_next_id+0x40/0xc2
[ 29.893172] [<c11b8689>] ? dqgrab+0x5e/0x5e
[ 29.893702] [<c11ba297>] dquot_get_next_dqblk+0x23/0x116
[ 29.894362] [<c11bdef5>] quota_getnextquota+0x7b/0x18c
[ 29.895003] [<c107549f>] ? kvm_clock_read+0x1f/0x29
[ 29.895612] [<c10754be>] ? kvm_sched_clock_read+0x9/0x18
[ 29.896273] [<c1059960>] ? paravirt_sched_clock+0x9/0xd
[ 29.896930] [<c10bcb85>] ? lock_acquire+0x11c/0x188
[ 29.897541] [<c10baa64>] ? lock_acquired+0xdf/0x2d7
[ 29.898150] [<c1177f3c>] ? get_super+0x54/0x93
[ 29.898709] [<c16ec37d>] ? down_read+0x62/0x69
[ 29.899267] [<c138c7ea>] ? security_capable+0x2d/0x40
[ 29.899909] [<c108d13b>] ? ns_capable+0x3c/0x55
[ 29.900478] [<c11be917>] SyS_quotactl+0x355/0x691
[ 29.901069] [<c10b84a2>] ? up_read+0x22/0x25
[ 29.901612] [<c10779fb>] ? __do_page_fault+0x378/0x3f5
[ 29.902255] [<c1001640>] do_int80_syscall_32+0x4d/0x5f
[ 29.902901] [<c16edc83>] entry_INT80_32+0x2f/0x2f
[ 29.903518] ---[ end trace 41bdb730582c4072 ]---
[ 29.904090] quid->type is 0, NULL ops array
[ 29.904613] BUG: unable to handle kernel NULL pointer dereference at 0000001c
[ 29.905494] IP: [<c11b8712>] dquot_get_next_id+0x89/0xc2
[ 29.906255] *pdpt = 000000003402d001 *pde = 0000000000000000
[ 29.907028] Oops: 0000 [#1] SMP
[ 29.907466] Modules linked in:
[ 29.907859] CPU: 0 PID: 2634 Comm: test-nextquota Tainted: G W 4.5.0-11280-g3d43bcf-dirty #516
[ 29.909060] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 29.909778] task: f41be200 ti: f34e2000 task.ti: f34e2000
[ 29.910441] EIP: 0060:[<c11b8712>] EFLAGS: 00010246 CPU: 0
[ 29.911118] EIP is at dquot_get_next_id+0x89/0xc2
[ 29.911698] EAX: ffffffda EBX: f61f7800 ECX: f6873000 EDX: 00000000
[ 29.912464] ESI: f34e3e2c EDI: f61f78cc EBP: f34e3e08 ESP: f34e3dfc
[ 29.913236] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 29.913905] CR0: 80050033 CR2: 0000001c CR3: 359cb780 CR4: 000006f0
[ 29.914708] Stack:
[ 29.914969] c11b8689 f34e3e7c f61f7800 f34e3e20 c11ba297 f34e3e2c f41be200 f61f7800
[ 29.916037] c1727400 f34e3ef8 c11bdef5 00000000 00000000 00000000 c107549f f41be200
[ 29.917086] f34e3e48 c10754be f41be200 f34e3e54 c1059960 c1a81794 f41be200 f41be200
[ 29.918140] Call Trace:
[ 29.918449] [<c11b8689>] ? dqgrab+0x5e/0x5e
[ 29.918976] [<c11ba297>] dquot_get_next_dqblk+0x23/0x116
[ 29.919651] [<c11bdef5>] quota_getnextquota+0x7b/0x18c
[ 29.920293] [<c107549f>] ? kvm_clock_read+0x1f/0x29
[ 29.920905] [<c10754be>] ? kvm_sched_clock_read+0x9/0x18
[ 29.921571] [<c1059960>] ? paravirt_sched_clock+0x9/0xd
[ 29.922224] [<c10bcb85>] ? lock_acquire+0x11c/0x188
[ 29.922836] [<c10baa64>] ? lock_acquired+0xdf/0x2d7
[ 29.923447] [<c1177f3c>] ? get_super+0x54/0x93
[ 29.924009] [<c16ec37d>] ? down_read+0x62/0x69
[ 29.924570] [<c138c7ea>] ? security_capable+0x2d/0x40
[ 29.925202] [<c108d13b>] ? ns_capable+0x3c/0x55
[ 29.925773] [<c11be917>] SyS_quotactl+0x355/0x691
[ 29.926364] [<c10b84a2>] ? up_read+0x22/0x25
[ 29.926899] [<c10779fb>] ? __do_page_fault+0x378/0x3f5
[ 29.927542] [<c1001640>] do_int80_syscall_32+0x4d/0x5f
[ 29.928184] [<c16edc83>] entry_INT80_32+0x2f/0x2f
[ 29.928777] Code: eb 1a 85 f6 75 07 68 f8 a4 95 c1 eb ed ff 76 04 68 04 a5 95 c1 e8 be bb f7 ff 58 5a 8b 46 04 8b 94 83 14 02 00 00 b8 da ff ff ff <83> 7a 1c 00 74 2b 8d bb d0 00 00 00 31 d2 89 f8 e8 21 22 53 00
[ 29.931955] EIP: [<c11b8712>] dquot_get_next_id+0x89/0xc2 SS:ESP 0068:f34e3dfc
[ 29.932867] CR2: 000000000000001c
[ 29.933302] ---[ end trace 41bdb730582c4073 ]---
Killed
root@...-xfstests:~# QEMU: Terminated
--
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