Security Vulnerabilities - CVEs Published In April 2026
In the Linux kernel, the following vulnerability has been resolved:
mm/huge_memory: fix folio isn't locked in softleaf_to_folio()
On arm64 server, we found folio that get from migration entry isn't locked
in softleaf_to_folio(). This issue triggers when mTHP splitting and
zap_nonpresent_ptes() races, and the root cause is lack of memory barrier
in softleaf_to_folio(). The race is as follows:
CPU0 CPU1
deferred_split_scan() zap_nonpresent_ptes()
lock folio
split_folio()
unmap_folio()
change ptes to migration entries
__split_folio_to_order() softleaf_to_folio()
set flags(including PG_locked) for tail pages folio = pfn_folio(softleaf_to_pfn(entry))
smp_wmb() VM_WARN_ON_ONCE(!folio_test_locked(folio))
prep_compound_page() for tail pages
In __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages
are visible before the tail page becomes non-compound. smp_wmb() should
be paired with smp_rmb() in softleaf_to_folio(), which is missed. As a
result, if zap_nonpresent_ptes() accesses migration entry that stores tail
pfn, softleaf_to_folio() may see the updated compound_head of tail page
before page->flags.
This issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()
because of the race between folio split and zap_nonpresent_ptes()
leading to a folio incorrectly undergoing modification without a folio
lock being held.
This is a BUG_ON() before commit 93976a20345b ("mm: eliminate further
swapops predicates"), which in merged in v6.19-rc1.
To fix it, add missing smp_rmb() if the softleaf entry is migration entry
in softleaf_to_folio() and softleaf_to_page().
[tujinjiang@huawei.com: update function name and comments]
CVSS Score
4.7
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
erofs: add GFP_NOIO in the bio completion if needed
The bio completion path in the process context (e.g. dm-verity)
will directly call into decompression rather than trigger another
workqueue context for minimal scheduling latencies, which can
then call vm_map_ram() with GFP_KERNEL.
Due to insufficient memory, vm_map_ram() may generate memory
swapping I/O, which can cause submit_bio_wait to deadlock
in some scenarios.
Trimmed down the call stack, as follows:
f2fs_submit_read_io
submit_bio //bio_list is initialized.
mmc_blk_mq_recovery
z_erofs_endio
vm_map_ram
__pte_alloc_kernel
__alloc_pages_direct_reclaim
shrink_folio_list
__swap_writepage
submit_bio_wait //bio_list is non-NULL, hang!!!
Use memalloc_noio_{save,restore}() to wrap up this path.
CVSS Score
7.5
EPSS Score
0.004
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/sysfs: check contexts->nr in repeat_call_fn
damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(),
damon_sysfs_upd_schemes_stats(), and
damon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr.
If nr_contexts is set to 0 via sysfs while DAMON is running, these
functions dereference contexts_arr[0] and cause a NULL pointer
dereference. Add the missing check.
For example, the issue can be reproduced using DAMON sysfs interface and
DAMON user-space tool (damo) [1] like below.
$ sudo damo start --refresh_interval 1s
$ echo 0 | sudo tee \
/sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]
Multiple sysfs command paths dereference contexts_arr[0] without first
verifying that kdamond->contexts->nr == 1. A user can set nr_contexts to
0 via sysfs while DAMON is running, causing NULL pointer dereferences.
In more detail, the issue can be triggered by privileged users like
below.
First, start DAMON and make contexts directory empty
(kdamond->contexts->nr == 0).
# damo start
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/nr_contexts
Then, each of below commands will cause the NULL pointer dereference.
# echo update_schemes_stats > state
# echo update_schemes_tried_regions > state
# echo update_schemes_tried_bytes > state
# echo update_schemes_effective_quotas > state
# echo update_tuned_intervals > state
Guard all commands (except OFF) at the entry point of
damon_sysfs_handle_cmd().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/sysfs: fix param_ctx leak on damon_sysfs_new_test_ctx() failure
Patch series "mm/damon/sysfs: fix memory leak and NULL dereference
issues", v4.
DAMON_SYSFS can leak memory under allocation failure, and do NULL pointer
dereference when a privileged user make wrong sequences of control. Fix
those.
This patch (of 3):
When damon_sysfs_new_test_ctx() fails in damon_sysfs_commit_input(),
param_ctx is leaked because the early return skips the cleanup at the out
label. Destroy param_ctx before returning.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: check if ext_caps is valid in BL setup
LVDS connectors don't have extended backlight caps so check
if the pointer is valid before accessing it.
(cherry picked from commit 3f797396d7f4eb9bb6eded184bbc6f033628a6f6)
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Fix drm_edid leak in amdgpu_dm
[WHAT]
When a sink is connected, aconnector->drm_edid was overwritten without
freeing the previous allocation, causing a memory leak on resume.
[HOW]
Free the previous drm_edid before updating it.
(cherry picked from commit 52024a94e7111366141cfc5d888b2ef011f879e5)
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: prevent immediate PASID reuse case
PASID resue could cause interrupt issue when process
immediately runs into hw state left by previous
process exited with the same PASID, it's possible that
page faults are still pending in the IH ring buffer when
the process exits and frees up its PASID. To prevent the
case, it uses idr cyclic allocator same as kernel pid's.
(cherry picked from commit 8f1de51f49be692de137c8525106e0fce2d1912d)
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
xfs: stop reclaim before pushing AIL during unmount
The unmount sequence in xfs_unmount_flush_inodes() pushed the AIL while
background reclaim and inodegc are still running. This is broken
independently of any use-after-free issues - background reclaim and
inodegc should not be running while the AIL is being pushed during
unmount, as inodegc can dirty and insert inodes into the AIL during the
flush, and background reclaim can race to abort and free dirty inodes.
Reorder xfs_unmount_flush_inodes() to stop inodegc and cancel background
reclaim before pushing the AIL. Stop inodegc before cancelling
m_reclaim_work because the inodegc worker can re-queue m_reclaim_work
via xfs_inodegc_set_reclaimable.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-04-22
In the Linux kernel, the following vulnerability has been resolved:
mm/pagewalk: fix race between concurrent split and refault
The splitting of a PUD entry in walk_pud_range() can race with a
concurrent thread refaulting the PUD leaf entry causing it to try walking
a PMD range that has disappeared.
An example and reproduction of this is to try reading numa_maps of a
process while VFIO-PCI is setting up DMA (specifically the
vfio_pin_pages_remote call) on a large BAR for that process.
This will trigger a kernel BUG:
vfio-pci 0000:03:00.0: enabling device (0000 -> 0002)
BUG: unable to handle page fault for address: ffffa23980000000
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
...
RIP: 0010:walk_pgd_range+0x3b5/0x7a0
Code: 8d 43 ff 48 89 44 24 28 4d 89 ce 4d 8d a7 00 00 20 00 48 8b 4c 24
28 49 81 e4 00 00 e0 ff 49 8d 44 24 ff 48 39 c8 4c 0f 43 e3 <49> f7 06
9f ff ff ff 75 3b 48 8b 44 24 20 48 8b 40 28 48 85 c0 74
RSP: 0018:ffffac23e1ecf808 EFLAGS: 00010287
RAX: 00007f44c01fffff RBX: 00007f4500000000 RCX: 00007f44ffffffff
RDX: 0000000000000000 RSI: 000ffffffffff000 RDI: ffffffff93378fe0
RBP: ffffac23e1ecf918 R08: 0000000000000004 R09: ffffa23980000000
R10: 0000000000000020 R11: 0000000000000004 R12: 00007f44c0200000
R13: 00007f44c0000000 R14: ffffa23980000000 R15: 00007f44c0000000
FS: 00007fe884739580(0000) GS:ffff9b7d7a9c0000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffa23980000000 CR3: 000000c0650e2005 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
__walk_page_range+0x195/0x1b0
walk_page_vma+0x62/0xc0
show_numa_map+0x12b/0x3b0
seq_read_iter+0x297/0x440
seq_read+0x11d/0x140
vfs_read+0xc2/0x340
ksys_read+0x5f/0xe0
do_syscall_64+0x68/0x130
? get_page_from_freelist+0x5c2/0x17e0
? mas_store_prealloc+0x17e/0x360
? vma_set_page_prot+0x4c/0xa0
? __alloc_pages_noprof+0x14e/0x2d0
? __mod_memcg_lruvec_state+0x8d/0x140
? __lruvec_stat_mod_folio+0x76/0xb0
? __folio_mod_stat+0x26/0x80
? do_anonymous_page+0x705/0x900
? __handle_mm_fault+0xa8d/0x1000
? __count_memcg_events+0x53/0xf0
? handle_mm_fault+0xa5/0x360
? do_user_addr_fault+0x342/0x640
? arch_exit_to_user_mode_prepare.constprop.0+0x16/0xa0
? irqentry_exit_to_user_mode+0x24/0x100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fe88464f47e
Code: c0 e9 b6 fe ff ff 50 48 8d 3d be 07 0b 00 e8 69 01 02 00 66 0f 1f
84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00
f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
RSP: 002b:00007ffe6cd9a9b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fe88464f47e
RDX: 0000000000020000 RSI: 00007fe884543000 RDI: 0000000000000003
RBP: 00007fe884543000 R08: 00007fe884542010 R09: 0000000000000000
R10: fffffffffffffbc5 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
</TASK>
Fix this by validating the PUD entry in walk_pmd_range() using a stable
snapshot (pudp_get()). If the PUD is not present or is a leaf, retry the
walk via ACTION_AGAIN instead of descending further. This mirrors the
retry logic in walk_pte_range(), which lets walk_pmd_range() retry if the
PTE is not being got by pte_offset_map_lock().
CVSS Score
4.7
EPSS Score
0.001
Published
2026-04-22