| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: ufs: core: Fix invalid probe error return value
After DME Link Startup, the error return value is set to the MIPI UniPro
GenericErrorCode which can be 0 (SUCCESS) or 1 (FAILURE). Upon failure
during driver probe, the error code 1 is propagated back to the driver
probe function which must return a negative value to indicate an error,
but 1 is not negative, so the probe is considered to be successful even
though it failed. Subsequently, removing the driver results in an oops
because it is not in a valid state.
This happens because none of the callers of ufshcd_init() expect a
non-negative error code.
Fix the return value and documentation to match actual usage. |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: core: Fix a regression triggered by scsi_host_busy()
Commit 995412e23bb2 ("blk-mq: Replace tags->lock with SRCU for tag
iterators") introduced the following regression:
Call trace:
__srcu_read_lock+0x30/0x80 (P)
blk_mq_tagset_busy_iter+0x44/0x300
scsi_host_busy+0x38/0x70
ufshcd_print_host_state+0x34/0x1bc
ufshcd_link_startup.constprop.0+0xe4/0x2e0
ufshcd_init+0x944/0xf80
ufshcd_pltfrm_init+0x504/0x820
ufs_rockchip_probe+0x2c/0x88
platform_probe+0x5c/0xa4
really_probe+0xc0/0x38c
__driver_probe_device+0x7c/0x150
driver_probe_device+0x40/0x120
__driver_attach+0xc8/0x1e0
bus_for_each_dev+0x7c/0xdc
driver_attach+0x24/0x30
bus_add_driver+0x110/0x230
driver_register+0x68/0x130
__platform_driver_register+0x20/0x2c
ufs_rockchip_pltform_init+0x1c/0x28
do_one_initcall+0x60/0x1e0
kernel_init_freeable+0x248/0x2c4
kernel_init+0x20/0x140
ret_from_fork+0x10/0x20
Fix this regression by making scsi_host_busy() check whether the SCSI
host tag set has already been initialized. tag_set->ops is set by
scsi_mq_setup_tags() just before blk_mq_alloc_tag_set() is called. This
fix is based on the assumption that scsi_host_busy() and
scsi_mq_setup_tags() calls are serialized. This is the case in the UFS
driver. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check NULL before accessing
[WHAT]
IGT kms_cursor_legacy's long-nonblocking-modeset-vs-cursor-atomic
fails with NULL pointer dereference. This can be reproduced with
both an eDP panel and a DP monitors connected.
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 13 UID: 0 PID: 2960 Comm: kms_cursor_lega Not tainted
6.16.0-99-custom #8 PREEMPT(voluntary)
Hardware name: AMD ........
RIP: 0010:dc_stream_get_scanoutpos+0x34/0x130 [amdgpu]
Code: 57 4d 89 c7 41 56 49 89 ce 41 55 49 89 d5 41 54 49
89 fc 53 48 83 ec 18 48 8b 87 a0 64 00 00 48 89 75 d0 48 c7 c6 e0 41 30
c2 <48> 8b 38 48 8b 9f 68 06 00 00 e8 8d d7 fd ff 31 c0 48 81 c3 e0 02
RSP: 0018:ffffd0f3c2bd7608 EFLAGS: 00010292
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffd0f3c2bd7668
RDX: ffffd0f3c2bd7664 RSI: ffffffffc23041e0 RDI: ffff8b32494b8000
RBP: ffffd0f3c2bd7648 R08: ffffd0f3c2bd766c R09: ffffd0f3c2bd7760
R10: ffffd0f3c2bd7820 R11: 0000000000000000 R12: ffff8b32494b8000
R13: ffffd0f3c2bd7664 R14: ffffd0f3c2bd7668 R15: ffffd0f3c2bd766c
FS: 000071f631b68700(0000) GS:ffff8b399f114000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001b8105000 CR4: 0000000000f50ef0
PKRU: 55555554
Call Trace:
<TASK>
dm_crtc_get_scanoutpos+0xd7/0x180 [amdgpu]
amdgpu_display_get_crtc_scanoutpos+0x86/0x1c0 [amdgpu]
? __pfx_amdgpu_crtc_get_scanout_position+0x10/0x10[amdgpu]
amdgpu_crtc_get_scanout_position+0x27/0x50 [amdgpu]
drm_crtc_vblank_helper_get_vblank_timestamp_internal+0xf7/0x400
drm_crtc_vblank_helper_get_vblank_timestamp+0x1c/0x30
drm_crtc_get_last_vbltimestamp+0x55/0x90
drm_crtc_next_vblank_start+0x45/0xa0
drm_atomic_helper_wait_for_fences+0x81/0x1f0
...
(cherry picked from commit 621e55f1919640acab25383362b96e65f2baea3c) |
| In the Linux kernel, the following vulnerability has been resolved:
NFS: Check the TLS certificate fields in nfs_match_client()
If the TLS security policy is of type RPC_XPRTSEC_TLS_X509, then the
cert_serial and privkey_serial fields need to match as well since they
define the client's identity, as presented to the server. |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: ipc: fix use-after-free in ipc_msg_send_request
ipc_msg_send_request() waits for a generic netlink reply using an
ipc_msg_table_entry on the stack. The generic netlink handler
(handle_generic_event()/handle_response()) fills entry->response under
ipc_msg_table_lock, but ipc_msg_send_request() used to validate and free
entry->response without holding the same lock.
Under high concurrency this allows a race where handle_response() is
copying data into entry->response while ipc_msg_send_request() has just
freed it, leading to a slab-use-after-free reported by KASAN in
handle_generic_event():
BUG: KASAN: slab-use-after-free in handle_generic_event+0x3c4/0x5f0 [ksmbd]
Write of size 12 at addr ffff888198ee6e20 by task pool/109349
...
Freed by task:
kvfree
ipc_msg_send_request [ksmbd]
ksmbd_rpc_open -> ksmbd_session_rpc_open [ksmbd]
Fix by:
- Taking ipc_msg_table_lock in ipc_msg_send_request() while validating
entry->response, freeing it when invalid, and removing the entry from
ipc_msg_table.
- Returning the final entry->response pointer to the caller only after
the hash entry is removed under the lock.
- Returning NULL in the error path, preserving the original API
semantics.
This makes all accesses to entry->response consistent with
handle_response(), which already updates and fills the response buffer
under ipc_msg_table_lock, and closes the race that allowed the UAF. |
| In the Linux kernel, the following vulnerability has been resolved:
clk: thead: th1520-ap: set all AXI clocks to CLK_IS_CRITICAL
The AXI crossbar of TH1520 has no proper timeout handling, which means
gating AXI clocks can easily lead to bus timeout and thus system hang.
Set all AXI clock gates to CLK_IS_CRITICAL. All these clock gates are
ungated by default on system reset.
In addition, convert all current CLK_IGNORE_UNUSED usage to
CLK_IS_CRITICAL to prevent unwanted clock gating. |
| In the Linux kernel, the following vulnerability has been resolved:
nvme-multipath: fix lockdep WARN due to partition scan work
Blktests test cases nvme/014, 057 and 058 fail occasionally due to a
lockdep WARN. As reported in the Closes tag URL, the WARN indicates that
a deadlock can happen due to the dependency among disk->open_mutex,
kblockd workqueue completion and partition_scan_work completion.
To avoid the lockdep WARN and the potential deadlock, cut the dependency
by running the partition_scan_work not by kblockd workqueue but by
nvme_wq. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/plane: Fix create_in_format_blob() return value
create_in_format_blob() is either supposed to return a valid
pointer or an error, but never NULL. The caller will dereference
the blob when it is not an error, and thus will oops if NULL
returned. Return proper error values in the failure cases. |
| In the Linux kernel, the following vulnerability has been resolved:
s390/pci: Avoid deadlock between PCI error recovery and mlx5 crdump
Do not block PCI config accesses through pci_cfg_access_lock() when
executing the s390 variant of PCI error recovery: Acquire just
device_lock() instead of pci_dev_lock() as powerpc's EEH and
generig PCI AER processing do.
During error recovery testing a pair of tasks was reported to be hung:
mlx5_core 0000:00:00.1: mlx5_health_try_recover:338:(pid 5553): health recovery flow aborted, PCI reads still not working
INFO: task kmcheck:72 blocked for more than 122 seconds.
Not tainted 5.14.0-570.12.1.bringup7.el9.s390x #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kmcheck state:D stack:0 pid:72 tgid:72 ppid:2 flags:0x00000000
Call Trace:
[<000000065256f030>] __schedule+0x2a0/0x590
[<000000065256f356>] schedule+0x36/0xe0
[<000000065256f572>] schedule_preempt_disabled+0x22/0x30
[<0000000652570a94>] __mutex_lock.constprop.0+0x484/0x8a8
[<000003ff800673a4>] mlx5_unload_one+0x34/0x58 [mlx5_core]
[<000003ff8006745c>] mlx5_pci_err_detected+0x94/0x140 [mlx5_core]
[<0000000652556c5a>] zpci_event_attempt_error_recovery+0xf2/0x398
[<0000000651b9184a>] __zpci_event_error+0x23a/0x2c0
INFO: task kworker/u1664:6:1514 blocked for more than 122 seconds.
Not tainted 5.14.0-570.12.1.bringup7.el9.s390x #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u1664:6 state:D stack:0 pid:1514 tgid:1514 ppid:2 flags:0x00000000
Workqueue: mlx5_health0000:00:00.0 mlx5_fw_fatal_reporter_err_work [mlx5_core]
Call Trace:
[<000000065256f030>] __schedule+0x2a0/0x590
[<000000065256f356>] schedule+0x36/0xe0
[<0000000652172e28>] pci_wait_cfg+0x80/0xe8
[<0000000652172f94>] pci_cfg_access_lock+0x74/0x88
[<000003ff800916b6>] mlx5_vsc_gw_lock+0x36/0x178 [mlx5_core]
[<000003ff80098824>] mlx5_crdump_collect+0x34/0x1c8 [mlx5_core]
[<000003ff80074b62>] mlx5_fw_fatal_reporter_dump+0x6a/0xe8 [mlx5_core]
[<0000000652512242>] devlink_health_do_dump.part.0+0x82/0x168
[<0000000652513212>] devlink_health_report+0x19a/0x230
[<000003ff80075a12>] mlx5_fw_fatal_reporter_err_work+0xba/0x1b0 [mlx5_core]
No kernel log of the exact same error with an upstream kernel is
available - but the very same deadlock situation can be constructed there,
too:
- task: kmcheck
mlx5_unload_one() tries to acquire devlink lock while the PCI error
recovery code has set pdev->block_cfg_access by way of
pci_cfg_access_lock()
- task: kworker
mlx5_crdump_collect() tries to set block_cfg_access through
pci_cfg_access_lock() while devlink_health_report() had acquired
the devlink lock.
A similar deadlock situation can be reproduced by requesting a
crdump with
> devlink health dump show pci/<BDF> reporter fw_fatal
while PCI error recovery is executed on the same <BDF> physical function
by mlx5_core's pci_error_handlers. On s390 this can be injected with
> zpcictl --reset-fw <BDF>
Tests with this patch failed to reproduce that second deadlock situation,
the devlink command is rejected with "kernel answers: Permission denied" -
and we get a kernel log message of:
mlx5_core 1ed0:00:00.1: mlx5_crdump_collect:50:(pid 254382): crdump: failed to lock vsc gw err -5
because the config read of VSC_SEMAPHORE is rejected by the underlying
hardware.
Two prior attempts to address this issue have been discussed and
ultimately rejected [see link], with the primary argument that s390's
implementation of PCI error recovery is imposing restrictions that
neither powerpc's EEH nor PCI AER handling need. Tests show that PCI
error recovery on s390 is running to completion even without blocking
access to PCI config space. |
| In the Linux kernel, the following vulnerability has been resolved:
io_uring/cmd_net: fix wrong argument types for skb_queue_splice()
If timestamp retriving needs to be retried and the local list of
SKB's already has entries, then it's spliced back into the socket
queue. However, the arguments for the splice helper are transposed,
causing exactly the wrong direction of splicing into the on-stack
list. Fix that up. |
| In the Linux kernel, the following vulnerability has been resolved:
libceph: prevent potential out-of-bounds writes in handle_auth_session_key()
The len field originates from untrusted network packets. Boundary
checks have been added to prevent potential out-of-bounds writes when
decrypting the connection secret or processing service tickets.
[ idryomov: changelog ] |
| In the Linux kernel, the following vulnerability has been resolved:
most: usb: fix double free on late probe failure
The MOST subsystem has a non-standard registration function which frees
the interface on registration failures and on deregistration.
This unsurprisingly leads to bugs in the MOST drivers, and a couple of
recent changes turned a reference underflow and use-after-free in the
USB driver into several double free and a use-after-free on late probe
failures. |
| In the Linux kernel, the following vulnerability has been resolved:
NFS: Fix LTP test failures when timestamps are delegated
The utimes01 and utime06 tests fail when delegated timestamps are
enabled, specifically in subtests that modify the atime and mtime
fields using the 'nobody' user ID.
The problem can be reproduced as follow:
# echo "/media *(rw,no_root_squash,sync)" >> /etc/exports
# export -ra
# mount -o rw,nfsvers=4.2 127.0.0.1:/media /tmpdir
# cd /opt/ltp
# ./runltp -d /tmpdir -s utimes01
# ./runltp -d /tmpdir -s utime06
This issue occurs because nfs_setattr does not verify the inode's
UID against the caller's fsuid when delegated timestamps are
permitted for the inode.
This patch adds the UID check and if it does not match then the
request is sent to the server for permission checking. |
| In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to detect potential corrupted nid in free_nid_list
As reported, on-disk footer.ino and footer.nid is the same and
out-of-range, let's add sanity check on f2fs_alloc_nid() to detect
any potential corruption in free_nid_list. |
| In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix incomplete backport in cfids_invalidation_worker()
The previous commit bdb596ceb4b7 ("smb: client: fix potential UAF in
smb2_close_cached_fid()") was an incomplete backport and missed one
kref_put() call in cfids_invalidation_worker() that should have been
converted to close_cached_dir(). |
| In the Linux kernel, the following vulnerability has been resolved:
mm/mempool: fix poisoning order>0 pages with HIGHMEM
The kernel test has reported:
BUG: unable to handle page fault for address: fffba000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
*pde = 03171067 *pte = 00000000
Oops: Oops: 0002 [#1]
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: G T 6.18.0-rc2-00031-gec7f31b2a2d3 #1 NONE a1d066dfe789f54bc7645c7989957d2bdee593ca
Tainted: [T]=RANDSTRUCT
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
EIP: memset (arch/x86/include/asm/string_32.h:168 arch/x86/lib/memcpy_32.c:17)
Code: a5 8b 4d f4 83 e1 03 74 02 f3 a4 83 c4 04 5e 5f 5d 2e e9 73 41 01 00 90 90 90 3e 8d 74 26 00 55 89 e5 57 56 89 c6 89 d0 89 f7 <f3> aa 89 f0 5e 5f 5d 2e e9 53 41 01 00 cc cc cc 55 89 e5 53 57 56
EAX: 0000006b EBX: 00000015 ECX: 001fefff EDX: 0000006b
ESI: fffb9000 EDI: fffba000 EBP: c611fbf0 ESP: c611fbe8
DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010287
CR0: 80050033 CR2: fffba000 CR3: 0316e000 CR4: 00040690
Call Trace:
poison_element (mm/mempool.c:83 mm/mempool.c:102)
mempool_init_node (mm/mempool.c:142 mm/mempool.c:226)
mempool_init_noprof (mm/mempool.c:250 (discriminator 1))
? mempool_alloc_pages (mm/mempool.c:640)
bio_integrity_initfn (block/bio-integrity.c:483 (discriminator 8))
? mempool_alloc_pages (mm/mempool.c:640)
do_one_initcall (init/main.c:1283)
Christoph found out this is due to the poisoning code not dealing
properly with CONFIG_HIGHMEM because only the first page is mapped but
then the whole potentially high-order page is accessed.
We could give up on HIGHMEM here, but it's straightforward to fix this
with a loop that's mapping, poisoning or checking and unmapping
individual pages. |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: target: tcm_loop: Fix segfault in tcm_loop_tpg_address_show()
If the allocation of tl_hba->sh fails in tcm_loop_driver_probe() and we
attempt to dereference it in tcm_loop_tpg_address_show() we will get a
segfault, see below for an example. So, check tl_hba->sh before
dereferencing it.
Unable to allocate struct scsi_host
BUG: kernel NULL pointer dereference, address: 0000000000000194
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 1 PID: 8356 Comm: tokio-runtime-w Not tainted 6.6.104.2-4.azl3 #1
Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 09/28/2024
RIP: 0010:tcm_loop_tpg_address_show+0x2e/0x50 [tcm_loop]
...
Call Trace:
<TASK>
configfs_read_iter+0x12d/0x1d0 [configfs]
vfs_read+0x1b5/0x300
ksys_read+0x6f/0xf0
... |
| In the Linux kernel, the following vulnerability has been resolved:
libceph: fix potential use-after-free in have_mon_and_osd_map()
The wait loop in __ceph_open_session() can race with the client
receiving a new monmap or osdmap shortly after the initial map is
received. Both ceph_monc_handle_map() and handle_one_map() install
a new map immediately after freeing the old one
kfree(monc->monmap);
monc->monmap = monmap;
ceph_osdmap_destroy(osdc->osdmap);
osdc->osdmap = newmap;
under client->monc.mutex and client->osdc.lock respectively, but
because neither is taken in have_mon_and_osd_map() it's possible for
client->monc.monmap->epoch and client->osdc.osdmap->epoch arms in
client->monc.monmap && client->monc.monmap->epoch &&
client->osdc.osdmap && client->osdc.osdmap->epoch;
condition to dereference an already freed map. This happens to be
reproducible with generic/395 and generic/397 with KASAN enabled:
BUG: KASAN: slab-use-after-free in have_mon_and_osd_map+0x56/0x70
Read of size 4 at addr ffff88811012d810 by task mount.ceph/13305
CPU: 2 UID: 0 PID: 13305 Comm: mount.ceph Not tainted 6.14.0-rc2-build2+ #1266
...
Call Trace:
<TASK>
have_mon_and_osd_map+0x56/0x70
ceph_open_session+0x182/0x290
ceph_get_tree+0x333/0x680
vfs_get_tree+0x49/0x180
do_new_mount+0x1a3/0x2d0
path_mount+0x6dd/0x730
do_mount+0x99/0xe0
__do_sys_mount+0x141/0x180
do_syscall_64+0x9f/0x100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
Allocated by task 13305:
ceph_osdmap_alloc+0x16/0x130
ceph_osdc_init+0x27a/0x4c0
ceph_create_client+0x153/0x190
create_fs_client+0x50/0x2a0
ceph_get_tree+0xff/0x680
vfs_get_tree+0x49/0x180
do_new_mount+0x1a3/0x2d0
path_mount+0x6dd/0x730
do_mount+0x99/0xe0
__do_sys_mount+0x141/0x180
do_syscall_64+0x9f/0x100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 9475:
kfree+0x212/0x290
handle_one_map+0x23c/0x3b0
ceph_osdc_handle_map+0x3c9/0x590
mon_dispatch+0x655/0x6f0
ceph_con_process_message+0xc3/0xe0
ceph_con_v1_try_read+0x614/0x760
ceph_con_workfn+0x2de/0x650
process_one_work+0x486/0x7c0
process_scheduled_works+0x73/0x90
worker_thread+0x1c8/0x2a0
kthread+0x2ec/0x300
ret_from_fork+0x24/0x40
ret_from_fork_asm+0x1a/0x30
Rewrite the wait loop to check the above condition directly with
client->monc.mutex and client->osdc.lock taken as appropriate. While
at it, improve the timeout handling (previously mount_timeout could be
exceeded in case wait_event_interruptible_timeout() slept more than
once) and access client->auth_err under client->monc.mutex to match
how it's set in finish_auth().
monmap_show() and osdmap_show() now take the respective lock before
accessing the map as well. |
| In the Linux kernel, the following vulnerability has been resolved:
lan966x: Fix sleeping in atomic context
The following warning was seen when we try to connect using ssh to the device.
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:575
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 104, name: dropbear
preempt_count: 1, expected: 0
INFO: lockdep is turned off.
CPU: 0 UID: 0 PID: 104 Comm: dropbear Tainted: G W 6.18.0-rc2-00399-g6f1ab1b109b9-dirty #530 NONE
Tainted: [W]=WARN
Hardware name: Generic DT based system
Call trace:
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x7c/0xac
dump_stack_lvl from __might_resched+0x16c/0x2b0
__might_resched from __mutex_lock+0x64/0xd34
__mutex_lock from mutex_lock_nested+0x1c/0x24
mutex_lock_nested from lan966x_stats_get+0x5c/0x558
lan966x_stats_get from dev_get_stats+0x40/0x43c
dev_get_stats from dev_seq_printf_stats+0x3c/0x184
dev_seq_printf_stats from dev_seq_show+0x10/0x30
dev_seq_show from seq_read_iter+0x350/0x4ec
seq_read_iter from seq_read+0xfc/0x194
seq_read from proc_reg_read+0xac/0x100
proc_reg_read from vfs_read+0xb0/0x2b0
vfs_read from ksys_read+0x6c/0xec
ksys_read from ret_fast_syscall+0x0/0x1c
Exception stack(0xf0b11fa8 to 0xf0b11ff0)
1fa0: 00000001 00001000 00000008 be9048d8 00001000 00000001
1fc0: 00000001 00001000 00000008 00000003 be905920 0000001e 00000000 00000001
1fe0: 0005404c be9048c0 00018684 b6ec2cd8
It seems that we are using a mutex in a atomic context which is wrong.
Change the mutex with a spinlock. |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Don't skip unrelated instruction if INT3/INTO is replaced
When re-injecting a soft interrupt from an INT3, INT0, or (select) INTn
instruction, discard the exception and retry the instruction if the code
stream is changed (e.g. by a different vCPU) between when the CPU
executes the instruction and when KVM decodes the instruction to get the
next RIP.
As effectively predicted by commit 6ef88d6e36c2 ("KVM: SVM: Re-inject
INT3/INTO instead of retrying the instruction"), failure to verify that
the correct INTn instruction was decoded can effectively clobber guest
state due to decoding the wrong instruction and thus specifying the
wrong next RIP.
The bug most often manifests as "Oops: int3" panics on static branch
checks in Linux guests. Enabling or disabling a static branch in Linux
uses the kernel's "text poke" code patching mechanism. To modify code
while other CPUs may be executing that code, Linux (temporarily)
replaces the first byte of the original instruction with an int3 (opcode
0xcc), then patches in the new code stream except for the first byte,
and finally replaces the int3 with the first byte of the new code
stream. If a CPU hits the int3, i.e. executes the code while it's being
modified, then the guest kernel must look up the RIP to determine how to
handle the #BP, e.g. by emulating the new instruction. If the RIP is
incorrect, then this lookup fails and the guest kernel panics.
The bug reproduces almost instantly by hacking the guest kernel to
repeatedly check a static branch[1] while running a drgn script[2] on
the host to constantly swap out the memory containing the guest's TSS.
[1]: https://gist.github.com/osandov/44d17c51c28c0ac998ea0334edf90b5a
[2]: https://gist.github.com/osandov/10e45e45afa29b11e0c7209247afc00b |
