In the Linux kernel, the following vulnerability has been resolved:
USB: core: Limit the length of unkillable synchronous timeouts
The usb_control_msg(), usb_bulk_msg(), and usb_interrupt_msg() APIs in
usbcore allow unlimited timeout durations. And since they use
uninterruptible waits, this leaves open the possibility of hanging a
task for an indefinitely long time, with no way to kill it short of
unplugging the target device.
To prevent this sort of problem, enforce a maximum limit on the length
of these unkillable timeouts. The limit chosen here, somewhat
arbitrarily, is 60 seconds. On many systems (although not all) this
is short enough to avoid triggering the kernel's hung-task detector.
In addition, clear up the ambiguity of negative timeout values by
treating them the same as 0, i.e., using the maximum allowed timeout.
In the Linux kernel, the following vulnerability has been resolved:
scsi: ufs: core: Fix SError in ufshcd_rtc_work() during UFS suspend
In __ufshcd_wl_suspend(), cancel_delayed_work_sync() is called to cancel
the UFS RTC work, but it is placed after ufshcd_vops_suspend(hba, pm_op,
POST_CHANGE). This creates a race condition where ufshcd_rtc_work() can
still be running while ufshcd_vops_suspend() is executing. When
UFSHCD_CAP_CLK_GATING is not supported, the condition
!hba->clk_gating.active_reqs is always true, causing ufshcd_update_rtc()
to be executed. Since ufshcd_vops_suspend() typically performs clock
gating operations, executing ufshcd_update_rtc() at that moment triggers
an SError. The kernel panic trace is as follows:
Kernel panic - not syncing: Asynchronous SError Interrupt
Call trace:
dump_backtrace+0xec/0x128
show_stack+0x18/0x28
dump_stack_lvl+0x40/0xa0
dump_stack+0x18/0x24
panic+0x148/0x374
nmi_panic+0x3c/0x8c
arm64_serror_panic+0x64/0x8c
do_serror+0xc4/0xc8
el1h_64_error_handler+0x34/0x4c
el1h_64_error+0x68/0x6c
el1_interrupt+0x20/0x58
el1h_64_irq_handler+0x18/0x24
el1h_64_irq+0x68/0x6c
ktime_get+0xc4/0x12c
ufshcd_mcq_sq_stop+0x4c/0xec
ufshcd_mcq_sq_cleanup+0x64/0x1dc
ufshcd_clear_cmd+0x38/0x134
ufshcd_issue_dev_cmd+0x298/0x4d0
ufshcd_exec_dev_cmd+0x1a4/0x1c4
ufshcd_query_attr+0xbc/0x19c
ufshcd_rtc_work+0x10c/0x1c8
process_scheduled_works+0x1c4/0x45c
worker_thread+0x32c/0x3e8
kthread+0x120/0x1d8
ret_from_fork+0x10/0x20
Fix this by moving cancel_delayed_work_sync() before the call to
ufshcd_vops_suspend(hba, pm_op, PRE_CHANGE), ensuring the UFS RTC work is
fully completed or cancelled at that point.
In the Linux kernel, the following vulnerability has been resolved:
powerpc, perf: Check that current->mm is alive before getting user callchain
It may happen that mm is already released, which leads to kernel panic.
This adds the NULL check for current->mm, similarly to
commit 20afc60f892d ("x86, perf: Check that current->mm is alive before getting user callchain").
I was getting this panic when running a profiling BPF program
(profile.py from bcc-tools):
[26215.051935] Kernel attempted to read user page (588) - exploit attempt? (uid: 0)
[26215.051950] BUG: Kernel NULL pointer dereference on read at 0x00000588
[26215.051952] Faulting instruction address: 0xc00000000020fac0
[26215.051957] Oops: Kernel access of bad area, sig: 11 [#1]
[...]
[26215.052049] Call Trace:
[26215.052050] [c000000061da6d30] [c00000000020fc10] perf_callchain_user_64+0x2d0/0x490 (unreliable)
[26215.052054] [c000000061da6dc0] [c00000000020f92c] perf_callchain_user+0x1c/0x30
[26215.052057] [c000000061da6de0] [c0000000005ab2a0] get_perf_callchain+0x100/0x360
[26215.052063] [c000000061da6e70] [c000000000573bc8] bpf_get_stackid+0x88/0xf0
[26215.052067] [c000000061da6ea0] [c008000000042258] bpf_prog_16d4ab9ab662f669_do_perf_event+0xf8/0x274
[...]
In addition, move storing the top-level stack entry to generic
perf_callchain_user to make sure the top-evel entry is always captured,
even if current->mm is NULL.
[Maddy: fixed message to avoid checkpatch format style error]
In the Linux kernel, the following vulnerability has been resolved:
sched/mmcid: Handle vfork()/CLONE_VM correctly
Matthieu and Jiri reported stalls where a task endlessly loops in
mm_get_cid() when scheduling in.
It turned out that the logic which handles vfork()'ed tasks is broken. It
is invoked when the number of tasks associated to a process is smaller than
the number of MMCID users. It then walks the task list to find the
vfork()'ed task, but accounts all the already processed tasks as well.
If that double processing brings the number of to be handled tasks to 0,
the walk stops and the vfork()'ed task's CID is not fixed up. As a
consequence a subsequent schedule in fails to acquire a (transitional) CID
and the machine stalls.
Cure this by removing the accounting condition and make the fixup always
walk the full task list if it could not find the exact number of users in
the process' thread list.
In the Linux kernel, the following vulnerability has been resolved:
sched/mmcid: Prevent CID stalls due to concurrent forks
A newly forked task is accounted as MMCID user before the task is visible
in the process' thread list and the global task list. This creates the
following problem:
CPU1 CPU2
fork()
sched_mm_cid_fork(tnew1)
tnew1->mm.mm_cid_users++;
tnew1->mm_cid.cid = getcid()
-> preemption
fork()
sched_mm_cid_fork(tnew2)
tnew2->mm.mm_cid_users++;
// Reaches the per CPU threshold
mm_cid_fixup_tasks_to_cpus()
for_each_other(current, p)
....
As tnew1 is not visible yet, this fails to fix up the already allocated CID
of tnew1. As a consequence a subsequent schedule in might fail to acquire a
(transitional) CID and the machine stalls.
Move the invocation of sched_mm_cid_fork() after the new task becomes
visible in the thread and the task list to prevent this.
This also makes it symmetrical vs. exit() where the task is removed as CID
user before the task is removed from the thread and task lists.
In the Linux kernel, the following vulnerability has been resolved:
ceph: fix memory leaks in ceph_mdsc_build_path()
Add __putname() calls to error code paths that did not free the "path"
pointer obtained by __getname(). If ownership of this pointer is not
passed to the caller via path_info.path, the function must free it
before returning.
In the Linux kernel, the following vulnerability has been resolved:
libceph: Use u32 for non-negative values in ceph_monmap_decode()
This patch fixes unnecessary implicit conversions that change signedness
of blob_len and num_mon in ceph_monmap_decode().
Currently blob_len and num_mon are (signed) int variables. They are used
to hold values that are always non-negative and get assigned in
ceph_decode_32_safe(), which is meant to assign u32 values. Both
variables are subsequently used as unsigned values, and the value of
num_mon is further assigned to monmap->num_mon, which is of type u32.
Therefore, both variables should be of type u32. This is especially
relevant for num_mon. If the value read from the incoming message is
very large, it is interpreted as a negative value, and the check for
num_mon > CEPH_MAX_MON does not catch it. This leads to the attempt to
allocate a very large chunk of memory for monmap, which will most likely
fail. In this case, an unnecessary attempt to allocate memory is
performed, and -ENOMEM is returned instead of -EINVAL.
In the Linux kernel, the following vulnerability has been resolved:
libceph: prevent potential out-of-bounds reads in process_message_header()
If the message frame is (maliciously) corrupted in a way that the
length of the control segment ends up being less than the size of the
message header or a different frame is made to look like a message
frame, out-of-bounds reads may ensue in process_message_header().
Perform an explicit bounds check before decoding the message header.