vdanen/rhvex-cve huggingface dataset:
CVE-2021-47292 (Low severity, published 2024-05-20)
CVSS score: 4.4 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

io_uring: fix memleak in io_init_wq_offload()

I got memory leak report when doing fuzz test:

BUG: memory leak
unreferenced object 0xffff888107310a80 (size 96):
comm "syz-executor.6", pid 4610, jiffies 4295140240 (age 20.135s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
backtrace:
[<000000001974933b>] kmalloc include/linux/slab.h:591 [inline]
[<000000001974933b>] kzalloc include/linux/slab.h:721 [inline]
[<000000001974933b>] io_init_wq_offload fs/io_uring.c:7920 [inline]
[<000000001974933b>] io_uring_alloc_task_context+0x466/0x640 fs/io_uring.c:7955
[<0000000039d0800d>] __io_uring_add_tctx_node+0x256/0x360 fs/io_uring.c:9016
[<000000008482e78c>] io_uring_add_tctx_node fs/io_uring.c:9052 [inline]
[<000000008482e78c>] __do_sys_io_uring_enter fs/io_uring.c:9354 [inline]
[<000000008482e78c>] __se_sys_io_uring_enter fs/io_uring.c:9301 [inline]
[<000000008482e78c>] __x64_sys_io_uring_enter+0xabc/0xc20 fs/io_uring.c:9301
[<00000000b875f18f>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<00000000b875f18f>] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
[<000000006b0a8484>] entry_SYSCALL_64_after_hwframe+0x44/0xae

CPU0                          CPU1
io_uring_enter                io_uring_enter
io_uring_add_tctx_node        io_uring_add_tctx_node
__io_uring_add_tctx_node      __io_uring_add_tctx_node
io_uring_alloc_task_context   io_uring_alloc_task_context
io_init_wq_offload            io_init_wq_offload
hash = kzalloc                hash = kzalloc
ctx->hash_map = hash          ctx->hash_map = hash <- one of the hash is leaked

When calling io_uring_enter() in parallel, the 'hash_map' will be leaked,
add uring_lock to protect 'hash_map'.
CVE-2021-47338 (Moderate severity, published 2024-05-20)
CVSS score: 5.1 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H)
CWE: CWE-416
Description: A vulnerability was found in the Linux kernel's fbmem subsystem. This issue arises when the system attempts to delete a video mode that is still in use, leading to potential use-after-free errors. This improper handling can result in system crashes or undefined behavior when accessing freed memory.
Statement: This vulnerability is rated as a moderate severity because this issue affects system reliability by potentially causing errors when video modes are incorrectly managed, but it does not compromise the system's overall security posture or data integrity.
Mitigation: Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.
CVE-2021-3587 (None severity, published 2021-05-31)
CVSS score: 0 (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:N)
CWE: CWE-476
Description: A flaw was found in the Linux kernel. A null pointer dereference in llcp_sock_getname in net/nfc/llcp_sock.c can lead to an unprivileged user triggering this bug, causing denial of service.
Statement: This flaw was found to be a duplicate of CVE-2021-38208. Please see https://access.redhat.com/security/cve/CVE-2021-38208 for information about affected products and security errata.
CVE-2021-37939 (Low severity, published 2021-11-09)
CVSS score: 2.7 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N)
CWE: CWE-319
Description: An information disclosure flaw was found in kibana. A malicious user with the ability to create connectors could utilize the JIRA and IBM Resilient connectors to view limited HTTP response data on hosts accessible to the cluster.
CVE-2021-20205 (Low severity, published 2021-03-09)
CVSS score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)
CWE: CWE-369
Description: A flaw was found in libjpeg-turbo (versions 2.0.91 and 2.0.90) and is vulnerable to a denial of service issue caused by a divide by zero when processing a crafted GIF image. The highest threat from this vulnerability	is to system availability.
Statement: This flaw does not affect versions of libjpeg-turbo shipped with Red Hat Enterprise Linux versions 6, 7, or 8. Additionally, it is not in the library, only the cjpeg utility.
CVE-2021-33096 (Moderate severity, published 2022-02-18)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-668
Description: A denial-of-service flaw was found due to improper isolation of shared resources in the network on chip for the Intel(R) 82599 Ethernet Controllers and Adapters. This may allow an authenticated user to potentially create a denial of service via local access.
Statement: There was no shipped kernel version that was seen affected by this problem.
Mitigation: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
CVE-2021-23995 (Important severity, published 2021-04-18)
CVSS score: 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
CWE: CWE-416
Description: When Responsive Design Mode was enabled, it used references to objects that were previously freed. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.
CVE-2021-32687 (Important severity, published 2021-10-03)
CVSS score: 7.5 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H)
CWE: CWE-787
Description: An integer overflow issue was found in redis. The vulnerability involves changing the default "set-max-intset-entries" configuration parameter to a very large value and constructing specially crafted commands to manipulate sets. This flaw allows a remote attacker to leak arbitrary contents of the heap or potentially trigger remote code execution. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
Mitigation: The flaw can be mitigated by disallowing usage of the CONFIG SET command via ACL configuration. This will prevent clients from setting the `set-max-intset-entries` configuration parameter. Please see https://redis.io/topics/acl for more information on how to do this.
CVE-2021-4184 (Moderate severity, published 2021-12-28)
CVSS score: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-835
Description: An infinite-loop flaw was found in Wireshark's DHT dissector module. This flaw allows an attacker with local network access to pass specially crafted capture files, causing an application to halt, crash or go into an infinite loop.
CVE-2021-33645 (Moderate severity, published 2022-08-09)
CVSS score: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-401
Description: A flaw was found in libtar. This security vulnerability occurs because the th_read() function in libtar doesn’t free a variable t->th_buf.gnu_longlink after allocating memory, which may cause a memory leak.
CVE-2021-47154 (Moderate severity, published 2024-03-17)
CVSS score: 6.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L)
CWE: CWE-20
Description: A vulnerability was found in the Perl module Net::CIDR::Lite, where extraneous zero characters at the start of an IP address string are not adequately handled. This flaw may enable attackers to circumvent IP address-based access controls in certain scenarios.
CVE-2021-23215 (Low severity, published 2021-03-16)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)
CWE: CWE-400
Description: An integer overflow leading to a heap-buffer overflow was found in the DwaCompressor of  OpenEXR. An attacker could use this flaw to crash an application compiled with OpenEXR.
CVE-2021-47504 (Low severity, published 2024-05-23)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-99
Description: In the Linux kernel, the following vulnerability has been resolved:

io_uring: ensure task_work gets run as part of cancelations

If we successfully cancel a work item but that work item needs to be
processed through task_work, then we can be sleeping uninterruptibly
in io_uring_cancel_generic() and never process it. Hence we don't
make forward progress and we end up with an uninterruptible sleep
warning.

While in there, correct a comment that should be IFF, not IIF.
CVE-2021-47011 (Moderate severity, published 2024-02-27)
CVSS score: 7.1 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H)
CWE: CWE-416
Description: In the Linux kernel, the following vulnerability has been resolved:

mm: memcontrol: slab: fix obtain a reference to a freeing memcg

Patch series "Use obj_cgroup APIs to charge kmem pages", v5.

Since Roman's series "The new cgroup slab memory controller" applied.
All slab objects are charged with the new APIs of obj_cgroup.  The new
APIs introduce a struct obj_cgroup to charge slab objects.  It prevents
long-living objects from pinning the original memory cgroup in the
memory.  But there are still some corner objects (e.g.  allocations
larger than order-1 page on SLUB) which are not charged with the new
APIs.  Those objects (include the pages which are allocated from buddy
allocator directly) are charged as kmem pages which still hold a
reference to the memory cgroup.

E.g.  We know that the kernel stack is charged as kmem pages because the
size of the kernel stack can be greater than 2 pages (e.g.  16KB on
x86_64 or arm64).  If we create a thread (suppose the thread stack is
charged to memory cgroup A) and then move it from memory cgroup A to
memory cgroup B.  Because the kernel stack of the thread hold a
reference to the memory cgroup A.  The thread can pin the memory cgroup
A in the memory even if we remove the cgroup A.  If we want to see this
scenario by using the following script.  We can see that the system has
added 500 dying cgroups (This is not a real world issue, just a script
to show that the large kmallocs are charged as kmem pages which can pin
the memory cgroup in the memory).

	#!/bin/bash

	cat /proc/cgroups | grep memory

	cd /sys/fs/cgroup/memory
	echo 1 > memory.move_charge_at_immigrate

	for i in range{1..500}
	do
		mkdir kmem_test
		echo $$ > kmem_test/cgroup.procs
		sleep 3600 &
		echo $$ > cgroup.procs
		echo `cat kmem_test/cgroup.procs` > cgroup.procs
		rmdir kmem_test
	done

	cat /proc/cgroups | grep memory

This patchset aims to make those kmem pages to drop the reference to
memory cgroup by using the APIs of obj_cgroup.  Finally, we can see that
the number of the dying cgroups will not increase if we run the above test
script.

This patch (of 7):

The rcu_read_lock/unlock only can guarantee that the memcg will not be
freed, but it cannot guarantee the success of css_get (which is in the
refill_stock when cached memcg changed) to memcg.

  rcu_read_lock()
  memcg = obj_cgroup_memcg(old)
  __memcg_kmem_uncharge(memcg)
      refill_stock(memcg)
          if (stock->cached != memcg)
              // css_get can change the ref counter from 0 back to 1.
              css_get(&memcg->css)
  rcu_read_unlock()

This fix is very like the commit:

  eefbfa7fd678 ("mm: memcg/slab: fix use after free in obj_cgroup_charge")

Fix this by holding a reference to the memcg which is passed to the
__memcg_kmem_uncharge() before calling __memcg_kmem_uncharge().
CVE-2021-21697 (Important severity, published 2021-11-04)
CVSS score: 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
CWE: CWE-22
Description: An incorrect access restriction vulnerability was found in Jenkins. The directories agents are allowed to access include the directories where there are stored build-related information intended to allow agents to store build-related metadata during build execution. As a consequence, this allows an attacker who controls agent process to read and write the contents of any build directory stored in Jenkins with very few restrictions (build.xml and some Pipeline-related metadata).
Mitigation: Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.
CVE-2021-25284 (Moderate severity, published 2021-02-24)
CVSS score: 4.1 (CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N)
CWE: CWE-312
Description: A flaw was found in salt. Webutils write passwords in cleartext to /var/log/salt/minion.
CVE-2021-28662 (Moderate severity, published 2021-05-09)
CVSS score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)
CWE: CWE-20
Description: An input validation flaw was found in Squid. This issue could allow a remote server to perform a denial of service against all clients using the proxy when delivering HTTP response messages. The highest threat from this vulnerability is to system availability.
Statement: The versions of `squid` as shipped with Red Hat Enterprise Linux 6 and 7 are not affected by this flaw, as the vulnerable code was introduced in a later version of the package.
Mitigation: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
CVE-2021-29970 (Important severity, published 2021-07-12)
CVSS score: 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
CWE: CWE-416
Description: A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*. This vulnerability affects Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.
CVE-2021-20252 (Moderate severity, published 2021-01-21)
CVSS score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-20
Description: A flaw was found in 3scale. The 3scale backend does not perform preventive handling on user-requested date ranges in certain queries allowing a malicious authenticated user to submit a request with a sufficiently large date range to eventually yield an internal server error resulting in denial of service. The highest threat from this vulnerability is to system availability.
CVE-2021-36386 (Moderate severity, published 2021-07-27)
CVSS score: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-665
Description: A flaw was found in fetchmail. The flaw lies in how fetchmail when running in verbose mode using the -v flag tries to log long messages that are created from long headers. An attacker could potentially use this flaw to cause a Denial of Service attack or crash. The highest threat from this vulnerability is to data availability. This flaw was earlier identified by CVE-2008-2711 and fixed, however it recently got reintroduced due to a code refactoring issue. The current bug fix applies a different approach than the earlier one.
CVE-2021-46987 (Moderate severity, published 2024-02-27)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-833
Description: A vulnerability was found in the Linux kernel’s btrfs module, where there are a few exceptional cases when cloning an inline extent needs to copy the inline extent data into a page of the destination inode.  When this happens, a transaction starts while having a dirty page for the destination inode and while having the range locked in the destination's inode iotree. When reserving metadata space for a transaction, flushing the existing delalloc is needed in case there is not enough free space. There is a mechanism in place to prevent a deadlock, which was introduced in commit 3d45f221ce627d ("btrfs: fix deadlock when cloning inline extent and low on free metadata space").

However, when using qgroups, a transaction also reserves metadata qgroup space, which can also result in flushing delalloc in case there is not enough available space. When this happens, a deadlock occurs, since flushing delalloc requires locking the file range in the inode's iotree and the range was already locked at the very beginning of the clone operation, before attempting to start the transaction.
Statement: Red Hat Enterprise Linux 8 and 9 are not affected by this CVE, as they do not include Btrfs filesystem support (CONFIG_BTRFS_FS is not set).
Mitigation: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
CVE-2021-3929 (Moderate severity, published 2021-12-15)
CVSS score: 8.2 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H)
CWE: CWE-416
Description: A DMA reentrancy issue was found in the NVM Express Controller (NVME) emulation in QEMU. This CVE is similar to CVE-2021-3750 and, just like it, when the reentrancy write triggers the reset function nvme_ctrl_reset(), data structs will be freed leading to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition or, potentially, executing arbitrary code within the context of the QEMU process on the host.
Statement: The `qemu-kvm` package as shipped with Red Hat Enterprise Linux is not affected by this flaw as it does not include support for NVMe device emulation.
CVE-2021-0606 (Moderate severity, published 2021-06-21)
CVSS score: 5.1 (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
CWE: CWE-200
Description: A flaw was found in the Linux kernel. The function drm_syncobj_handle_to_fd first calls drm_syncobj_find which increments the refcount of the object on success. In all of the drm_syncobj_handle_to_fd error paths, the refcount is decremented, but in the success path the refcount should remain at +1 as the struct drm_syncobj now belongs to the newly opened file. Instead, the refcount was incremented again to +2.
Statement: This is Android kernel specific backport problem, not present in Red Hat supported kernels.
CVE-2021-46968 (Low severity, published 2024-02-26)
CVSS score: 2.3 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L)
CWE: CWE-402
Description: In the Linux kernel, the following vulnerability has been resolved:

s390/zcrypt: fix zcard and zqueue hot-unplug memleak

Tests with kvm and a kmemdebug kernel showed, that on hot unplug the
zcard and zqueue structs for the unplugged card or queue are not
properly freed because of a mismatch with get/put for the embedded
kref counter.

This fix now adjusts the handling of the kref counters. With init the
kref counter starts with 1. This initial value needs to drop to zero
with the unregister of the card or queue to trigger the release and
free the object.
Statement: No Red Hat Products are affected by this vulnerability.
CVE-2021-32280 (Moderate severity, published 2020-08-09)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)
CWE: CWE-476
Description: The transfig package is susceptible to a NULL pointer dereference on crafted input. While translating fig code, patterns which include incomplete closed splines lead to this software flaw. The highest threat from this vulnerability is availability.
CVE-2021-47380 (Low severity, published 2024-05-20)
CVSS score: 4.4 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-476
Description: In the Linux kernel, the following vulnerability has been resolved:

HID: amd_sfh: Fix potential NULL pointer dereference

devm_add_action_or_reset() can suddenly invoke amd_mp2_pci_remove() at
registration that will cause NULL pointer dereference since
corresponding data is not initialized yet. The patch moves
initialization of data before devm_add_action_or_reset().

Found by Linux Driver Verification project (linuxtesting.org).

[jkosina@suse.cz: rebase]
CVE-2021-20317 (Moderate severity, published 2021-09-23)
CVSS score: 4.4 (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)
CWE: CWE-665
Description: A flaw was found in the Linux kernel. A corrupted timer tree caused the task wakeup to be missing in the timerqueue_add function in lib/timerqueue.c. This flaw allows a local attacker with special user privileges to cause a denial of service, slowing and eventually stopping the system while running OSP. The highest threat from this vulnerability is system availability.
Mitigation: In order to mitigate this issue, it is possible to prevent the affected code by loading the kvm module with "pi_inject_timer=0" parameter.
~~~
rmmod kvm_intel kvm
modprobe kvm pi_inject_timer=0 
modprobe kvm_intel
~~~
CVE-2021-3495 (Important severity, published 2021-05-11)
CVSS score: 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
CWE: CWE-281
Description: An incorrect access control flaw was found in the kiali-operator. This flaw allows an attacker with a basic level of access to the cluster (to deploy a kiali operand) to use this vulnerability and deploy a given image to anywhere in the cluster, potentially gaining access to privileged service account tokens. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Statement: In regards to the ServiceMesh `openshift-service-mesh/kiali-rhel7` container, it has been superseded by the `openshift-service-mesh/kiali-rhel8` container and is no longer supported.
CVE-2021-47553 (Moderate severity, published 2024-05-23)
CVSS score: 6.1 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L)
CWE: CWE-402
Description: In the Linux kernel, the following vulnerability has been resolved:

sched/scs: Reset task stack state in bringup_cpu()

To hot unplug a CPU, the idle task on that CPU calls a few layers of C
code before finally leaving the kernel. When KASAN is in use, poisoned
shadow is left around for each of the active stack frames, and when
shadow call stacks are in use. When shadow call stacks (SCS) are in use
the task's saved SCS SP is left pointing at an arbitrary point within
the task's shadow call stack.

When a CPU is offlined than onlined back into the kernel, this stale
state can adversely affect execution. Stale KASAN shadow can alias new
stackframes and result in bogus KASAN warnings. A stale SCS SP is
effectively a memory leak, and prevents a portion of the shadow call
stack being used. Across a number of hotplug cycles the idle task's
entire shadow call stack can become unusable.

We previously fixed the KASAN issue in commit:

  e1b77c92981a5222 ("sched/kasan: remove stale KASAN poison after hotplug")

... by removing any stale KASAN stack poison immediately prior to
onlining a CPU.

Subsequently in commit:

  f1a0a376ca0c4ef1 ("sched/core: Initialize the idle task with preemption disabled")

... the refactoring left the KASAN and SCS cleanup in one-time idle
thread initialization code rather than something invoked prior to each
CPU being onlined, breaking both as above.

We fixed SCS (but not KASAN) in commit:

  63acd42c0d4942f7 ("sched/scs: Reset the shadow stack when idle_task_exit")

... but as this runs in the context of the idle task being offlined it's
potentially fragile.

To fix these consistently and more robustly, reset the SCS SP and KASAN
shadow of a CPU's idle task immediately before we online that CPU in
bringup_cpu(). This ensures the idle task always has a consistent state
when it is running, and removes the need to so so when exiting an idle
task.

Whenever any thread is created, dup_task_struct() will give the task a
stack which is free of KASAN shadow, and initialize the task's SCS SP,
so there's no need to specially initialize either for idle thread within
init_idle(), as this was only necessary to handle hotplug cycles.

I've tested this on arm64 with:

* gcc 11.1.0, defconfig +KASAN_INLINE, KASAN_STACK
* clang 12.0.0, defconfig +KASAN_INLINE, KASAN_STACK, SHADOW_CALL_STACK

... offlining and onlining CPUS with:

| while true; do
|   for C in /sys/devices/system/cpu/cpu*/online; do
|     echo 0 > $C;
|     echo 1 > $C;
|   done
| done
CVE-2021-47103 (Moderate severity, published 2024-03-03)
CVSS score: 7.1 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H)
CWE: CWE-416
Description: A use-after-free vulnerability was found in the TCP IP protocol in the Linux Kernel, where a delete operation of the RCU-protected pointer is supposed to clear the pointer before the call_rcu()/synchronize_rcu() guarding the actual memory freeing. This flaw allows a local attacker to crash the system or leak kernel internal information.