Public bug reported:
[IMPACT]
Commit 3b9a907223d7 (ipmi: fix sleep-in-atomic in free_user at cleanup SRCU
user->release_barrier)
pushes the removal of an ipmi_user into the system's workqueue.
Whenever an ipmi_user struct is about to be removed it is scheduled as a
work on the system's workqueue to guarantee the free operation won't be
executed in atomic context. When the work is executed the
free_user_work() function is invoked which frees the ipmi_user.
When ipmi_msghandler module is removed in cleanup_ipmi() function, there is no
check if there are any pending works to be executed.
Therefore, there is a potential race condition :
An ipmi_user is scheduled for removal and shortly after to remove the
ipmi_msghandler module.
If the scheduled work delays execution for any reason and the module is removed
first, then when the work is executed the pages of free_user_work() are gone
and the system crashes with the following :
BUG: unable to handle page fault for address: ffffffffc05c3450
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 635420e067 P4D 635420e067 PUD 6354210067 PMD 4711e51067 PTE 0
Oops: 0010 [#1] SMP PTI
CPU: 19 PID: 29646 Comm: kworker/19:1 Kdump: loaded Not tainted
5.4.0-77-generic #86~18.04.1-Ubuntu
Hardware name: Ciara Technologies ORION RS610-G4-DTH4S/MR91-FS1-Y9, BIOS F29
05/23/2019
Workqueue: events 0xffffffffc05c3450
RIP: 0010:0xffffffffc05c3450
Code: Bad RIP value.
RSP: 0018:ffffb721333c3e88 EFLAGS: 00010286
RAX: ffffffffc05c3450 RBX: ffff92a95f56a740 RCX: ffffb7221cfd14e8
RDX: 0000000000000001 RSI: ffff92616040d4b0 RDI: ffffb7221cf404e0
RBP: ffffb721333c3ec0 R08: 000073746e657665 R09: 8080808080808080
R10: ffffb721333c3de0 R11: fefefefefefefeff R12: ffff92a95f570700
R13: ffff92a0a40ece40 R14: ffffb7221cf404e0 R15: 0ffff92a95f57070
FS: 0000000000000000(0000) GS:ffff92a95f540000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffc05c3426 CR3: 00000081e9bfc005 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
? process_one_work+0x20f/0x400
worker_thread+0x34/0x410
kthread+0x121/0x140
? process_one_work+0x400/0x400
? kthread_park+0x90/0x90
ret_from_fork+0x35/0x40
Modules linked in: xt_REDIRECT xt_owner ipt_rpfilter xt_CT xt_multiport xt_set
ip_set_hash_ip veth xt_statistic ipt_REJECT
... megaraid_sas ahci libahci wmi [last unloaded: ipmi_msghandler]
CR2: ffffffffc05c3450
[TEST CASE]
The user who reported the issue can reproduce reliably by stopping the ipmi
related services and then removing the ipmi modules.
I could reproduce the issue only when turning the normal 'work' to delayed work.
[WHERE PROBLEMS COULD OCCUR]
TBD
[OTHER]
Upstream is affected too, working on a patch to address this.
** Affects: linux (Ubuntu)
Importance: Medium
Assignee: Ioanna Alifieraki (joalif)
Status: In Progress
** Affects: linux (Ubuntu Focal)
Importance: Medium
Assignee: Ioanna Alifieraki (joalif)
Status: Confirmed
** Affects: linux (Ubuntu Hirsute)
Importance: Medium
Assignee: Ioanna Alifieraki (joalif)
Status: Confirmed
** Affects: linux (Ubuntu Impish)
Importance: Medium
Assignee: Ioanna Alifieraki (joalif)
Status: Confirmed
** Affects: linux (Ubuntu Jammy)
Importance: Medium
Assignee: Ioanna Alifieraki (joalif)
Status: In Progress
** Also affects: linux (Ubuntu Focal)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Hirsute)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Impish)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Jammy)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Focal)
Importance: Undecided => Medium
** Changed in: linux (Ubuntu Hirsute)
Importance: Undecided => Medium
** Changed in: linux (Ubuntu Impish)
Importance: Undecided => Medium
** Changed in: linux (Ubuntu Jammy)
Importance: Undecided => Medium
** Changed in: linux (Ubuntu Focal)
Status: New => Confirmed
** Changed in: linux (Ubuntu Hirsute)
Status: New => Confirmed
** Changed in: linux (Ubuntu Impish)
Status: New => Confirmed
** Changed in: linux (Ubuntu Jammy)
Status: New => In Progress
** Changed in: linux (Ubuntu Jammy)
Assignee: (unassigned) => Ioanna Alifieraki (joalif)
** Changed in: linux (Ubuntu Impish)
Assignee: (unassigned) => Ioanna Alifieraki (joalif)
** Changed in: linux (Ubuntu Hirsute)
Assignee: (unassigned) => Ioanna Alifieraki (joalif)
** Changed in: linux (Ubuntu Focal)
Assignee: (unassigned) => Ioanna Alifieraki (joalif)
** Description changed:
[IMPACT]
Commit 3b9a907223d7 (ipmi: fix sleep-in-atomic in free_user at cleanup SRCU
user->release_barrier)
pushes the removal of an ipmi_user into the system's workqueue.
- Whenever an ipmi_user struct is about to be removed it is scheduled as a work
on
- the system's workqueue to guarantee the free operation won't be executed in
atomic context.
- When the work is executed the free_user_work() function is invoked which
frees the ipmi_user.
+ Whenever an ipmi_user struct is about to be removed it is scheduled as a
+ work on the system's workqueue to guarantee the free operation won't be
+ executed in atomic context. When the work is executed the
+ free_user_work() function is invoked which frees the ipmi_user.
- When ipmi_msghandler module is removed in cleanup_ipmi() function, there is
no
- check if there are any pending works to be executed.
- Therefore, there is a potential race condition :
- An ipmi_user is scheduled for removal and shortly to remove ipmi_msghandler
module.
- If the scheduled work delays execution for any reason and the module is
removed
- first then when the work is executed the pages of free_user_work() are gone
and
- the system crashes with the following :
+ When ipmi_msghandler module is removed in cleanup_ipmi() function, there is
no check if there are any pending works to be executed.
+ Therefore, there is a potential race condition :
+ An ipmi_user is scheduled for removal and shortly after to remove the
ipmi_msghandler module.
+ If the scheduled work delays execution for any reason and the module is
removed first, then when the work is executed the pages of free_user_work() are
gone and the system crashes with the following :
BUG: unable to handle page fault for address: ffffffffc05c3450
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 635420e067 P4D 635420e067 PUD 6354210067 PMD 4711e51067 PTE 0
Oops: 0010 [#1] SMP PTI
CPU: 19 PID: 29646 Comm: kworker/19:1 Kdump: loaded Not tainted
5.4.0-77-generic #86~18.04.1-Ubuntu
Hardware name: Ciara Technologies ORION RS610-G4-DTH4S/MR91-FS1-Y9, BIOS F29
05/23/2019
Workqueue: events 0xffffffffc05c3450
RIP: 0010:0xffffffffc05c3450
Code: Bad RIP value.
RSP: 0018:ffffb721333c3e88 EFLAGS: 00010286
RAX: ffffffffc05c3450 RBX: ffff92a95f56a740 RCX: ffffb7221cfd14e8
RDX: 0000000000000001 RSI: ffff92616040d4b0 RDI: ffffb7221cf404e0
RBP: ffffb721333c3ec0 R08: 000073746e657665 R09: 8080808080808080
R10: ffffb721333c3de0 R11: fefefefefefefeff R12: ffff92a95f570700
R13: ffff92a0a40ece40 R14: ffffb7221cf404e0 R15: 0ffff92a95f57070
FS: 0000000000000000(0000) GS:ffff92a95f540000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffc05c3426 CR3: 00000081e9bfc005 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
? process_one_work+0x20f/0x400
worker_thread+0x34/0x410
kthread+0x121/0x140
? process_one_work+0x400/0x400
? kthread_park+0x90/0x90
ret_from_fork+0x35/0x40
- Modules linked in: xt_REDIRECT xt_owner ipt_rpfilter xt_CT xt_multiport
xt_set ip_set_hash_ip veth xt_statistic ipt_REJECT
+ Modules linked in: xt_REDIRECT xt_owner ipt_rpfilter xt_CT xt_multiport
xt_set ip_set_hash_ip veth xt_statistic ipt_REJECT
... megaraid_sas ahci libahci wmi [last unloaded: ipmi_msghandler]
CR2: ffffffffc05c3450
[TEST CASE]
+ The user who reported the issue can reproduce reliably by stopping the ipmi
related services and then removing the ipmi modules.
+ I could reproduce the issue only when turning the normal 'work' to delayed
work.
+
[WHERE PROBLEMS COULD OCCUR]
+
+ TBD
[OTHER]
Upstream is affected too, working on a patch to address this.
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https://bugs.launchpad.net/bugs/1950666
Title:
system crash when removing ipmi_msghandler module
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