Linux: >> Linux Kernel >> 6.6.144 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
powerpc/64s: Fix unmap race with PMD migration entries
The following race is possible with migration swap entries or
device-private THP entries. e.g. when move_pages is called on a PMD THP
page, then there maybe an intermediate state, where PMD entry acts as
a migration swap entry (pmd_present() is true). Then if an munmap
happens at the same time, then this VM_BUG_ON() can happen in
pmdp_huge_get_and_clear_full().
This patch fixes that.
Thread A: move_pages() syscall
add_folio_for_migration()
mmap_read_lock(mm)
folio_isolate_lru(folio)
mmap_read_unlock(mm)
do_move_pages_to_node()
migrate_pages()
try_to_migrate_one()
spin_lock(ptl)
set_pmd_migration_entry()
pmdp_invalidate() # PMD: _PAGE_INVALID | _PAGE_PTE | pfn
set_pmd_at() # PMD: migration swap entry (pmd_present=0)
spin_unlock(ptl)
[page copy phase] # <--- RACE WINDOW -->
Thread B: munmap()
mmap_write_downgrade(mm)
unmap_vmas() -> zap_pmd_range()
zap_huge_pmd()
__pmd_trans_huge_lock()
pmd_is_huge(): # !pmd_present && !pmd_none -> TRUE (swap entry)
pmd_lock() -> # spin_lock(ptl), waits for Thread A to release ptl
pmdp_huge_get_and_clear_full()
VM_BUG_ON(!pmd_present(*pmdp)) # HITS!
[ 287.738700][ T1867] ------------[ cut here ]------------
[ 287.743843][ T1867] kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:187!
cpu 0x0: Vector: 700 (Program Check) at [c00000044037f4f0]
pc: c000000000094ca4: pmdp_huge_get_and_clear_full+0x6c/0x23c
lr: c000000000645dec: zap_huge_pmd+0xb0/0x868
sp: c00000044037f790
msr: 800000000282b033
current = 0xc0000004032c1a00
paca = 0xc000000004fe0000 irqmask: 0x03 irq_happened: 0x09
pid = 1867, comm = a.out
kernel BUG at :187!
Linux version 6.19.0-12136-g14360d4f917c-dirty (powerpc64le-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #27 SMP PREEMPT Sun Feb 22 10:38:56 IST 2026
enter ? for help
[link register ] c000000000645dec zap_huge_pmd+0xb0/0x868
[c00000044037f790] c00000044037f7d0 (unreliable)
[c00000044037f7d0] c000000000645dcc zap_huge_pmd+0x90/0x868
[c00000044037f840] c0000000005724cc unmap_page_range+0x176c/0x1f40
[c00000044037fa00] c000000000572ea0 unmap_vmas+0xb0/0x1d8
[c00000044037fa90] c0000000005af254 unmap_region+0xb4/0x128
[c00000044037fb50] c0000000005af400 vms_complete_munmap_vmas+0x138/0x310
[c00000044037fbe0] c0000000005b0f1c do_vmi_align_munmap+0x1ec/0x238
[c00000044037fd30] c0000000005b3688 __vm_munmap+0x170/0x1f8
[c00000044037fdf0] c000000000587f74 sys_munmap+0x2c/0x40
[c00000044037fe10] c000000000032668 system_call_exception+0x128/0x350
[c00000044037fe50] c00000000000d05c system_call_vectored_common+0x15c/0x2ec
---- Exception: 3000 (System Call Vectored) at 0000000010064a2c
SP (7fff9b1ee9c0) is in userspace
0:mon> zh
commit a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone device pages"),
enabled migration for device-private PMD entries. Hence this is one
other path where this warning could get trigger from.
------------[ cut here ]------------
WARNING: arch/powerpc/mm/book3s64/hash_pgtable.c:199 at hash__pmd_hugepage_update+0x48/0x284, CPU#3: hmm-tests/1905
Modules linked in: test_hmm
CPU: 3 UID: 0 PID: 1905 Comm: hmm-tests Tainted: G B W L N 7.0.0-rc1-01438-g7e2f0ee7581c #21 PREEMPT
Tainted: [B]=BAD_PAGE, [W]=WARN, [L]=SOFTLOCKUP, [N]=TEST
Hardware name: IBM pSeries (emulated by qemu) POWER10 (architected) 0x801200 0xf000006 of:SLOF,git-ee03ae pSeries
NIP [c000000000096b70] hash__pmd_hugepage_update+0x48/0x284
LR [c000000000096e7c] hash__pmdp_huge_get_and_clear+0xd0/0xd4
Call Trace:
[c000000604707670] [c000000004e102b8] 0xc000000004e102b8 (unreliable)
[c000000604707700] [c00000000064ec3c] set_pmd_migration_entry+0x414/0x498
[c000000604707760] [c00000000063e5a4] migrate_vma_col
---truncated---
CVSS Score
4.7
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
powerpc/pgtable-frag: Fix bad page state in pte_frag_destroy
powerpc uses pt_frag_refcount as a reference counter for tracking it's
pte and pmd page table fragments. For PTE table, in case of Hash with
64K pagesize, we have 16 fragments of 4K size in one 64K page.
Patch series [1] "mm: free retracted page table by RCU"
added pte_free_defer() to defer the freeing of PTE tables when
retract_page_tables() is called for madvise MADV_COLLAPSE on shmem
range.
[1]: https://lore.kernel.org/all/7cd843a9-aa80-14f-5eb2-33427363c20@google.com/
pte_free_defer() sets the active flag on the corresponding fragment's
folio & calls pte_fragment_free(), which reduces the pt_frag_refcount.
When pt_frag_refcount reaches 0 (no active fragment using the folio), it
checks if the folio active flag is set, if set, it calls call_rcu to
free the folio, it the active flag is unset then it calls pte_free_now().
Now, this can lead to following problem in a corner case...
[ 265.351553][ T183] BUG: Bad page state in process a.out pfn:20d62
[ 265.353555][ T183] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x20d62
[ 265.355457][ T183] flags: 0x3ffff800000100(active|node=0|zone=0|lastcpupid=0x7ffff)
[ 265.358719][ T183] raw: 003ffff800000100 0000000000000000 5deadbeef0000122 0000000000000000
[ 265.360177][ T183] raw: 0000000000000000 c0000000119caf58 00000000ffffffff 0000000000000000
[ 265.361438][ T183] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
[ 265.362572][ T183] Modules linked in:
[ 265.364622][ T183] CPU: 0 UID: 0 PID: 183 Comm: a.out Not tainted 6.18.0-rc3-00141-g1ddeaaace7ff-dirty #53 VOLUNTARY
[ 265.364785][ T183] Hardware name: IBM pSeries (emulated by qemu) POWER10 (architected) 0x801200 0xf000006 of:SLOF,git-ee03ae pSeries
[ 265.364908][ T183] Call Trace:
[ 265.364955][ T183] [c000000011e6f7c0] [c000000001cfaa18] dump_stack_lvl+0x130/0x148 (unreliable)
[ 265.365202][ T183] [c000000011e6f7f0] [c000000000794758] bad_page+0xb4/0x1c8
[ 265.365384][ T183] [c000000011e6f890] [c00000000079c020] __free_frozen_pages+0x838/0xd08
[ 265.365554][ T183] [c000000011e6f980] [c0000000000a70ac] pte_frag_destroy+0x298/0x310
[ 265.365729][ T183] [c000000011e6fa30] [c0000000000aa764] arch_exit_mmap+0x34/0x218
[ 265.365912][ T183] [c000000011e6fa80] [c000000000751698] exit_mmap+0xb8/0x820
[ 265.366080][ T183] [c000000011e6fc30] [c0000000001b1258] __mmput+0x98/0x300
[ 265.366244][ T183] [c000000011e6fc80] [c0000000001c81f8] do_exit+0x470/0x1508
[ 265.366421][ T183] [c000000011e6fd70] [c0000000001c95e4] do_group_exit+0x88/0x148
[ 265.366602][ T183] [c000000011e6fdc0] [c0000000001c96ec] pid_child_should_wake+0x0/0x178
[ 265.366780][ T183] [c000000011e6fdf0] [c00000000003a270] system_call_exception+0x1b0/0x4e0
[ 265.366958][ T183] [c000000011e6fe50] [c00000000000d05c] system_call_vectored_common+0x15c/0x2ec
The bad page state error occurs when such a folio gets freed (with
active flag set), from do_exit() path in parallel.
... this can happen when the pte fragment was allocated from this folio,
but when all the fragments get freed, the pte_frag_refcount still had some
unused fragments. Now, if this process exits, with such folio as it's cached
pte_frag in mm->context, then during pte_frag_destroy(), we simply call
pagetable_dtor() and pagetable_free(), meaning it doesn't clear the
active flag. This, can lead to the above bug. Since we are anyway in
do_exit() path, then if the refcount is 0, then I guess it should be
ok to simply clear the folio active flag before calling pagetable_dtor()
& pagetable_free().
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath11k: fix memory leaks in beacon template setup
The functions ath11k_mac_setup_bcn_tmpl_ema() and
ath11k_mac_setup_bcn_tmpl_mbssid() allocate memory for beacon templates
but fail to free it when parameter setup returns an error.
Since beacon templates must be released during normal execution, they
must also be released in the error handling paths to prevent memory
leaks.
Fix this by using unified exit paths with proper cleanup in the respective
error paths.
Compile tested only. Issue found using a prototype static analysis tool
and code review.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
bus: fsl-mc: use generic driver_override infrastructure
When a driver is probed through __driver_attach(), the bus' match()
callback is called without the device lock held, thus accessing the
driver_override field without a lock, which can cause a UAF.
Fix this by using the driver-core driver_override infrastructure taking
care of proper locking internally.
Note that calling match() from __driver_attach() without the device lock
held is intentional. [1]
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: Fix memory leak after mt76_connac_mcu_alloc_sta_req()
mt76_connac_mcu_alloc_sta_req() allocates an skb which is expected to
be freed eventually by mt76_mcu_skb_send_msg(). However, currently if
an intermediate function fails before sending, the allocated skb is
leaked.
Specifically, mt76_connac_mcu_sta_wed_update() and
mt76_connac_mcu_sta_key_tlv() may fail, leading to an immediate memory
leak in the error path.
Fix this by explicitly freeing the skb in these error paths.
Commit 7c0f63fe37a5 ("wifi: mt76: mt7996: fix memory leak on
mt7996_mcu_sta_key_tlv error") made a similar change.
Compile tested only. Issue found using a prototype static analysis tool
and code review.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
bpf: Do not allow deleting local storage in NMI
Currently, local storage may deadlock when deferring freeing selem or
local storage through kfree_rcu(), call_rcu() or call_rcu_tasks_trace()
in NMI or reentrant. Since deleting selem in NMI is an unlikely use
case, partially mitigate it by returning error when calling from
bpf_xxx_storage_delete() helpers in NMI. Note that, it is still possible
to deadlock through reentrant. A full mitigation requires returning
error when irqs_disabled() is true, which, however is too heavy-handed
for bpf_xxx_storage_delete().
The long-term solution requires _nolock versions of call_rcu. Another
possible solution is to defer the free through irq_work [0], but it
would grow the size of selem, which is non-ideal.
The check is only needed in bpf_selem_unlink(), which is used by helpers
and syscalls. bpf_selem_unlink_nofail() is fine as it is called during
map and owner tear down that never run in NMI or reentrant.
[0] https://lore.kernel.org/bpf/20260205190233.912-1-alexei.starovoitov@gmail.com/
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
wifi: libertas: don't kill URBs in interrupt context
Serialization for the TX path was enforced by calling
usb_kill_urb()/usb_kill_anchored_urbs(), to prevent transmission before
a previous URB was completed. usb_tx_block() can be called from
interrupt context (e.g. in the HCD giveback path), so we can't always
use it to kill in-flight URBs.
Prevent sleeping during interrupt context by checking the tx_submitted
anchor for existing URBs. We now return -EBUSY, to indicate there's
a pending request.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix use-after-free in offloaded map/prog info fill
When querying info for an offloaded BPF map or program,
bpf_map_offload_info_fill_ns() and bpf_prog_offload_info_fill_ns()
obtain the network namespace with get_net(dev_net(offmap->netdev)).
However, the associated netdev's netns may be racing with teardown
during netns destruction. If the netns refcount has already reached 0,
get_net() performs a refcount_t increment on 0, triggering:
refcount_t: addition on 0; use-after-free.
Although rtnl_lock and bpf_devs_lock ensure the netdev pointer remains
valid, they cannot prevent the netns refcount from reaching zero.
Fix this by using maybe_get_net() instead of get_net(). maybe_get_net()
uses refcount_inc_not_zero() and returns NULL if the refcount is already
zero, which causes ns_get_path_cb() to fail and the caller to return
-ENOENT -- the correct behavior when the netns is being destroyed.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix ld_{abs,ind} failure path analysis in subprogs
Usage of ld_{abs,ind} instructions got extended into subprogs some time
ago via commit 09b28d76eac4 ("bpf: Add abnormal return checks."). These
are only allowed in subprograms when the latter are BTF annotated and
have scalar return types.
The code generator in bpf_gen_ld_abs() has an abnormal exit path (r0=0 +
exit) from legacy cBPF times. While the enforcement is on scalar return
types, the verifier must also simulate the path of abnormal exit if the
packet data load via ld_{abs,ind} failed.
This is currently not the case. Fix it by having the verifier simulate
both success and failure paths, and extend it in similar ways as we do
for tail calls. The success path (r0=unknown, continue to next insn) is
pushed onto stack for later validation and the r0=0 and return to the
caller is done on the fall-through side.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
net: pull headers in qdisc_pkt_len_segs_init()
Most ndo_start_xmit() methods expects headers of gso packets
to be already in skb->head.
net/core/tso.c users are particularly at risk, because tso_build_hdr()
does a memcpy(hdr, skb->data, hdr_len);
qdisc_pkt_len_segs_init() already does a dissection of gso packets.
Use pskb_may_pull() instead of skb_header_pointer() to make
sure drivers do not have to reimplement this.
Some malicious packets could be fed, detect them so that we can
drop them sooner with a new SKB_DROP_REASON_SKB_BAD_GSO drop_reason.
CVSS Score
8.4
EPSS Score
0.001
Published
2026-06-24