vdanen/rhvex-cve huggingface dataset:
CVE-2025-37788 (Low severity, published 2025-04-30)
CVSS score: 3.3 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L)
CWE: CWE-401
Description: In the Linux kernel, the following vulnerability has been resolved:

cxgb4: fix memory leak in cxgb4_init_ethtool_filters() error path

In the for loop used to allocate the loc_array and bmap for each port, a
memory leak is possible when the allocation for loc_array succeeds,
but the allocation for bmap fails. This is because when the control flow
goes to the label free_eth_finfo, only the allocations starting from
(i-1)th iteration are freed.

Fix that by freeing the loc_array in the bmap allocation error path.
CVE-2025-2720 (None severity, published 2025-03-24)
CVSS score: 3.3 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)
CWE: CWE-457
Description: A vulnerability was found in GNOME libgsf, affecting the gsf_base64_encode_simple function. The attack needs to be approached locally, and manipulation of the size argument can lead to use of an uninitialized variable.
Statement: This CVE has been marked as Rejected by the assigning CNA. According to the code maintainer the call of the POC is invalid because the buffer pointed to by "data" must have "len" valid bytes. The docs were updated to make that clear.
CVE-2025-27788 (Important severity, published 2025-03-12)
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-125
Description: A flaw was found in the JSON gem for Ruby. This vulnerability causes an out-of-bounds read via a specially crafted document, possibly resulting in a crash.
Statement: No Red Hat products are vulnerable to this CVE, as it does not affect the versions or configurations of the products used in its distributions.
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-2025-22070 (Moderate severity, published 2025-04-15)
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-476
Description: In the Linux kernel, the following vulnerability has been resolved:

fs/9p: fix NULL pointer dereference on mkdir

When a 9p tree was mounted with option 'posixacl', parent directory had a
default ACL set for its subdirectories, e.g.:

  setfacl -m default:group:simpsons:rwx parentdir

then creating a subdirectory crashed 9p client, as v9fs_fid_add() call in
function v9fs_vfs_mkdir_dotl() sets the passed 'fid' pointer to NULL
(since dafbe689736) even though the subsequent v9fs_set_create_acl() call
expects a valid non-NULL 'fid' pointer:

  [   37.273191] BUG: kernel NULL pointer dereference, address: 0000000000000000
  ...
  [   37.322338] Call Trace:
  [   37.323043]  <TASK>
  [   37.323621] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434)
  [   37.324448] ? page_fault_oops (arch/x86/mm/fault.c:714)
  [   37.325532] ? search_module_extables (kernel/module/main.c:3733)
  [   37.326742] ? p9_client_walk (net/9p/client.c:1165) 9pnet
  [   37.328006] ? search_bpf_extables (kernel/bpf/core.c:804)
  [   37.329142] ? exc_page_fault (./arch/x86/include/asm/paravirt.h:686 arch/x86/mm/fault.c:1488 arch/x86/mm/fault.c:1538)
  [   37.330196] ? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:574)
  [   37.331330] ? p9_client_walk (net/9p/client.c:1165) 9pnet
  [   37.332562] ? v9fs_fid_xattr_get (fs/9p/xattr.c:30) 9p
  [   37.333824] v9fs_fid_xattr_set (fs/9p/fid.h:23 fs/9p/xattr.c:121) 9p
  [   37.335077] v9fs_set_acl (fs/9p/acl.c:276) 9p
  [   37.336112] v9fs_set_create_acl (fs/9p/acl.c:307) 9p
  [   37.337326] v9fs_vfs_mkdir_dotl (fs/9p/vfs_inode_dotl.c:411) 9p
  [   37.338590] vfs_mkdir (fs/namei.c:4313)
  [   37.339535] do_mkdirat (fs/namei.c:4336)
  [   37.340465] __x64_sys_mkdir (fs/namei.c:4354)
  [   37.341455] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
  [   37.342447] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Fix this by simply swapping the sequence of these two calls in
v9fs_vfs_mkdir_dotl(), i.e. calling v9fs_set_create_acl() before
v9fs_fid_add().
CVE-2025-27622 (Moderate severity, published 2025-03-05)
CVSS score: 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)
CWE: CWE-319
Description: A flaw was found in Jenkins and LTS. Affected versions of Jenkins do not redact the encrypted value of secrets when accessing `config.xml` agents via REST API or CLI, allowing attackers with Agent/Extended Read permission to view the encrypted value of secrets.
CVE-2025-38304 (Moderate severity, published 2025-07-09)
CVSS score: 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: Fix NULL pointer deference on eir_get_service_data

The len parameter is considered optional so it can be NULL so it cannot
be used for skipping to next entry of EIR_SERVICE_DATA.
CVE-2025-21575 (Moderate severity, published 2025-04-15)
CVSS score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Parser).  Supported versions that are affected are 8.0.0-8.0.41, 8.4.0-8.4.4 and  9.0.0-9.2.0. Easily exploitable vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Server.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.1 Base Score 6.5 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
CVE-2025-21826 (Moderate severity, published 2025-03-05)
CVSS score: 6.1 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H)
CWE: CWE-682
Description: In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: reject mismatching sum of field_len with set key length

The field length description provides the length of each separated key
field in the concatenation, each field gets rounded up to 32-bits to
calculate the pipapo rule width from pipapo_init(). The set key length
provides the total size of the key aligned to 32-bits.

Register-based arithmetics still allows for combining mismatching set
key length and field length description, eg. set key length 10 and field
description [ 5, 4 ] leading to pipapo width of 12.
CVE-2025-31125 (Moderate severity, published 2025-03-31)
CVSS score: 5.3 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N)
CWE: CWE-284
Description: A flaw was found in the Vite Node.js package. Vite exposes content of non-allowed files using `?inline&import` or `?raw?import`. Only apps explicitly exposing the Vite dev server to the network (using the `--host` or `server.host` config options) are affected.
CVE-2025-37858 (Moderate severity, published 2025-05-08)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

fs/jfs: Prevent integer overflow in AG size calculation

The JFS filesystem calculates allocation group (AG) size using 1 <<
l2agsize in dbExtendFS(). When l2agsize exceeds 31 (possible with >2TB
aggregates on 32-bit systems), this 32-bit shift operation causes undefined
behavior and improper AG sizing.

On 32-bit architectures:
- Left-shifting 1 by 32+ bits results in 0 due to integer overflow
- This creates invalid AG sizes (0 or garbage values) in
sbi->bmap->db_agsize
- Subsequent block allocations would reference invalid AG structures
- Could lead to:
  - Filesystem corruption during extend operations
  - Kernel crashes due to invalid memory accesses
  - Security vulnerabilities via malformed on-disk structures

Fix by casting to s64 before shifting:
bmp->db_agsize = (s64)1 << l2agsize;

This ensures 64-bit arithmetic even on 32-bit architectures. The cast
matches the data type of db_agsize (s64) and follows similar patterns in
JFS block calculation code.

Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVE-2025-21963 (Moderate severity, published 2025-03-31)
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-190
Description: In the Linux kernel, the following vulnerability has been resolved:

cifs: Fix integer overflow while processing acdirmax mount option

User-provided mount parameter acdirmax of type u32 is intended to have
an upper limit, but before it is validated, the value is converted from
seconds to jiffies which can lead to an integer overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVE-2025-50089 (Moderate severity, published 2025-07-15)
CVSS score: 4.9 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H)
Description: Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer).  Supported versions that are affected are 9.0.0-9.1.0. Easily exploitable vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.1 Base Score 4.9 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).
CVE-2025-43963 (Low severity, published 2025-04-19)
CVSS score: 2.9 (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L)
CWE: CWE-125
Description: In LibRaw before 0.21.4, phase_one_correct in decoders/load_mfbacks.cpp allows out-of-buffer access because split_col and split_row values are not checked in 0x041f tag processing.
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-2025-37771 (Moderate severity, published 2025-04-30)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

drm/amd/pm: Prevent division by zero

The user can set any speed value.
If speed is greater than UINT_MAX/8, division by zero is possible.

Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVE-2025-22123 (Moderate severity, published 2025-04-15)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to avoid accessing uninitialized curseg

syzbot reports a f2fs bug as below:

F2FS-fs (loop3): Stopped filesystem due to reason: 7
kworker/u8:7: attempt to access beyond end of device
BUG: unable to handle page fault for address: ffffed1604ea3dfa
RIP: 0010:get_ckpt_valid_blocks fs/f2fs/segment.h:361 [inline]
RIP: 0010:has_curseg_enough_space fs/f2fs/segment.h:570 [inline]
RIP: 0010:__get_secs_required fs/f2fs/segment.h:620 [inline]
RIP: 0010:has_not_enough_free_secs fs/f2fs/segment.h:633 [inline]
RIP: 0010:has_enough_free_secs+0x575/0x1660 fs/f2fs/segment.h:649
 <TASK>
 f2fs_is_checkpoint_ready fs/f2fs/segment.h:671 [inline]
 f2fs_write_inode+0x425/0x540 fs/f2fs/inode.c:791
 write_inode fs/fs-writeback.c:1525 [inline]
 __writeback_single_inode+0x708/0x10d0 fs/fs-writeback.c:1745
 writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976
 wb_writeback+0x413/0xb80 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x410/0x1080 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Commit 8b10d3653735 ("f2fs: introduce FAULT_NO_SEGMENT") allows to trigger
no free segment fault in allocator, then it will update curseg->segno to
NULL_SEGNO, though, CP_ERROR_FLAG has been set, f2fs_write_inode() missed
to check the flag, and access invalid curseg->segno directly in below call
path, then resulting in panic:

- f2fs_write_inode
 - f2fs_is_checkpoint_ready
  - has_enough_free_secs
   - has_not_enough_free_secs
    - __get_secs_required
     - has_curseg_enough_space
      - get_ckpt_valid_blocks
      : access invalid curseg->segno

To avoid this issue, let's:
- check CP_ERROR_FLAG flag in prior to f2fs_is_checkpoint_ready() in
f2fs_write_inode().
- in has_curseg_enough_space(), save curseg->segno into a temp variable,
and verify its validation before use.
CVE-2025-22066 (Moderate severity, published 2025-04-15)
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-476
Description: In the Linux kernel, the following vulnerability has been resolved:

ASoC: imx-card: Add NULL check in imx_card_probe()

devm_kasprintf() returns NULL when memory allocation fails. Currently,
imx_card_probe() does not check for this case, which results in a NULL
pointer dereference.

Add NULL check after devm_kasprintf() to prevent this issue.
CVE-2025-49178 (Moderate severity, published 2025-06-16)
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-667
Description: A flaw was found in the X server's request handling. Non-zero 'bytes to ignore' in a client's request can cause the server to skip processing another client's request, potentially leading to a denial of service.
Statement: This vulnerability is rated as a moderate severity because the flaw exists in the X server’s request handling logic, where the “bytes to ignore” field in a client request is not properly validated. A malicious client can submit a request specifying a non-zero 'bytes to ignore' value that exceeds the actual request size, causing the server to advance its internal input pointer incorrectly. As a result, the server may skip over pending requests from other clients, disrupting normal processing and effectively denying service to legitimate users. This vulnerability primarily impacts system availability
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-2025-38191 (Moderate severity, published 2025-07-03)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix null pointer dereference in destroy_previous_session

If client set ->PreviousSessionId on kerberos session setup stage,
NULL pointer dereference error will happen. Since sess->user is not
set yet, It can pass the user argument as NULL to destroy_previous_session.
sess->user will be set in ksmbd_krb5_authenticate(). So this patch move
calling destroy_previous_session() after ksmbd_krb5_authenticate().
CVE-2025-21830 (Low severity, published 2025-03-05)
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-20
Description: In the Linux kernel, the following vulnerability has been resolved:

landlock: Handle weird files

A corrupted filesystem (e.g. bcachefs) might return weird files.
Instead of throwing a warning and allowing access to such file, treat
them as regular files.
CVE-2025-5270 (Low severity, published 2025-05-27)
CVSS score: 3.4 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N)
CWE: CWE-319
Description: A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue: In certain cases, SNI could be sent unencrypted, even when encrypted DNS is enabled.
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
CVE-2025-30688 (Moderate severity, published 2025-04-15)
CVSS score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer).  Supported versions that are affected are 8.0.0-8.0.41, 8.4.0-8.4.4 and  9.0.0-9.2.0. Easily exploitable vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Server.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.1 Base Score 6.5 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
CVE-2025-38312 (Moderate severity, published 2025-07-09)
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-369
Description: In the Linux kernel, the following vulnerability has been resolved:

fbdev: core: fbcvt: avoid division by 0 in fb_cvt_hperiod()

In fb_find_mode_cvt(), iff mode->refresh somehow happens to be 0x80000000,
cvt.f_refresh will become 0 when multiplying it by 2 due to overflow. It's
then passed to fb_cvt_hperiod(), where it's used as a divider -- division
by 0 will result in kernel oops. Add a sanity check for cvt.f_refresh to
avoid such overflow...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.
Statement: A division-by-zero bug was fixed in the fb_cvt_hperiod() function of the framebuffer subsystem. Specifically, a malformed or extremely large refresh rate value could cause integer overflow in cvt.f_refresh, resulting in zero being passed to a division operation. This could lead to a kernel oops. The impact on availability is high, since it may cause the kernel to crash if invalid input is not filtered. The bug was found using the Svace static analyzer. Normally, framebuffer settings are modifiable only by root or kernel modules, so for the CVSS the required privileges High.
CVE-2025-30722 (Moderate severity, published 2025-04-15)
CVSS score: 5.9 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N)
Description: Vulnerability in the MySQL Client product of Oracle MySQL (component: Client: mysqldump).  Supported versions that are affected are 8.0.0-8.0.41, 8.4.0-8.4.4 and  9.0.0-9.2.0. Difficult to exploit vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Client.  Successful attacks of this vulnerability can result in  unauthorized access to critical data or complete access to all MySQL Client accessible data as well as  unauthorized update, insert or delete access to some of MySQL Client accessible data. CVSS 3.1 Base Score 5.9 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N).
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-2025-4877 (Moderate severity, published 2025-06-23)
CVSS score: 4.5 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L)
CWE: CWE-787
Description: No description is available for this CVE.
Statement: Red Hat Product Security classified this vulnerability as having a Moderate severity. This happens because of the complexity of the attack, the possible misusage of the libssh API and the fact the attacker may not have full control over the positions and contents written into the heap.

No supported Red Hat products are affected by this issue since only 32-bit builds are vulnerable.
CVE-2025-38257 (Moderate severity, published 2025-07-08)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

s390/pkey: Prevent overflow in size calculation for memdup_user()

Number of apqn target list entries contained in 'nr_apqns' variable is
determined by userspace via an ioctl call so the result of the product in
calculation of size passed to memdup_user() may overflow.

In this case the actual size of the allocated area and the value
describing it won't be in sync leading to various types of unpredictable
behaviour later.

Use a proper memdup_array_user() helper which returns an error if an
overflow is detected. Note that it is different from when nr_apqns is
initially zero - that case is considered valid and should be handled in
subsequent pkey_handler implementations.

Found by Linux Verification Center (linuxtesting.org).
CVE-2025-21975 (Moderate severity, published 2025-03-31)
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-476
Description: In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: handle errors in mlx5_chains_create_table()

In mlx5_chains_create_table(), the return value of mlx5_get_fdb_sub_ns()
and mlx5_get_flow_namespace() must be checked to prevent NULL pointer
dereferences. If either function fails, the function should log error
message with mlx5_core_warn() and return error pointer.
CVE-2025-1376 (Low severity, published 2025-02-16)
CVSS score: 2.5 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L)
CWE: CWE-404
Description: A flaw was found in GNU elfutils. This vulnerability allows denial of service via manipulation of the function elf_strptr in /libelf/elf_strptr.c.
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-2025-38083 (Moderate severity, published 2025-06-19)
CVSS score: 6.3 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H)
CWE: CWE-366
Description: In the Linux kernel, the following vulnerability has been resolved:

net_sched: prio: fix a race in prio_tune()

Gerrard Tai reported a race condition in PRIO, whenever SFQ perturb timer
fires at the wrong time.

The race is as follows:

CPU 0                                 CPU 1
[1]: lock root
[2]: qdisc_tree_flush_backlog()
[3]: unlock root
 |
 |                                    [5]: lock root
 |                                    [6]: rehash
 |                                    [7]: qdisc_tree_reduce_backlog()
 |
[4]: qdisc_put()

This can be abused to underflow a parent's qlen.

Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog()
should fix the race, because all packets will be purged from the qdisc
before releasing the lock.
CVE-2025-21758 (Moderate severity, published 2025-02-26)
CVSS score: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Description: In the Linux kernel, the following vulnerability has been resolved:

ipv6: mcast: add RCU protection to mld_newpack()

mld_newpack() can be called without RTNL or RCU being held.

Note that we no longer can use sock_alloc_send_skb() because
ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep.

Instead use alloc_skb() and charge the net->ipv6.igmp_sk
socket under RCU protection.