Linux: >> Linux Kernel >> 5.15.211 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ceph: only d_add() negative dentries when they are unhashed
Ceph can call d_add(dentry, NULL) on a negative dentry that is already
present in the primary dcache hash.
In the current VFS that is not safe. d_add() goes through __d_add()
to __d_rehash(), which unconditionally reinserts dentry->d_hash into
the hlist_bl bucket. If the dentry is already hashed, reinserting the
same node can corrupt the bucket, including creating a self-loop.
Once that happens, __d_lookup() can spin forever in the hlist_bl walk,
typically looping only on the d_name.hash mismatch check and
eventually triggering RCU stall reports like this one:
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 87-....: (2100 ticks this GP) idle=3a4c/1/0x4000000000000000 softirq=25003319/25003319 fqs=829
rcu: (t=2101 jiffies g=79058445 q=698988 ncpus=192)
CPU: 87 UID: 2952868916 PID: 3933303 Comm: php-cgi8.3 Not tainted 6.18.17-i1-amd #950 NONE
Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.6 09/22/2023
RIP: 0010:__d_lookup+0x46/0xb0
Code: c1 e8 07 48 8d 04 c2 48 8b 00 49 89 fc 49 89 f5 48 89 c3 48 83 e3 fe 48 83 f8 01 77 0f eb 2d 0f 1f 44 00 00 48 8b 1b 48 85 db <74> 20 39 6b 18 75 f3 48 8d 7b 78 e8 ba 85 d0 00 4c 39 63 10 74 1f
RSP: 0018:ff745a70c8253898 EFLAGS: 00000282
RAX: ff26e470054cb208 RBX: ff26e470054cb208 RCX: 000000006e958966
RDX: ff26e48267340000 RSI: ff745a70c82539b0 RDI: ff26e458f74655c0
RBP: 000000006e958966 R08: 0000000000000180 R09: 9cd08d909b919a89
R10: ff26e458f74655c0 R11: 0000000000000000 R12: ff26e458f74655c0
R13: ff745a70c82539b0 R14: d0d0d0d0d0d0d0d0 R15: 2f2f2f2f2f2f2f2f
FS: 00007f5770896980(0000) GS:ff26e482c5d88000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5764de50c0 CR3: 000000a72abb5001 CR4: 0000000000771ef0
PKRU: 55555554
Call Trace:
<TASK>
lookup_fast+0x9f/0x100
walk_component+0x1f/0x150
link_path_walk+0x20e/0x3d0
path_lookupat+0x68/0x180
filename_lookup+0xdc/0x1e0
vfs_statx+0x6c/0x140
vfs_fstatat+0x67/0xa0
__do_sys_newfstatat+0x24/0x60
do_syscall_64+0x6a/0x230
entry_SYSCALL_64_after_hwframe+0x76/0x7e
This is reachable with reused cached negative dentries. A Ceph lookup
or atomic_open can be handed a negative dentry that is already hashed,
and fs/ceph/dir.c then hits one of two paths that incorrectly assume
"negative" also means "unhashed":
- ceph_finish_lookup():
MDS reply is -ENOENT with no trace
-> d_add(dentry, NULL)
- ceph_lookup():
local ENOENT fast path for a complete directory with shared caps
-> d_add(dentry, NULL)
Both paths can therefore re-add an already-hashed negative dentry.
Ceph already uses the correct pattern elsewhere: ceph_fill_trace() only
calls d_add(dn, NULL) for a negative null-dentry reply when d_unhashed(dn)
is true.
Fix both fs/ceph/dir.c sites the same way: only call d_add() for a
negative dentry when it is actually unhashed. If the negative dentry
is already hashed, leave it in place and reuse it as-is.
This preserves the existing behavior for unhashed dentries while
avoiding d_hash list corruption for reused hashed negatives.
CVSS Score
7.5
EPSS Score
0.005
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
net: qrtr: ns: Free the node during ctrl_cmd_bye()
A node sends the BYE packet when it is about to go down. So the nameserver
should advertise the removal of the node to all remote and local observers
and free the node finally. But currently, the nameserver doesn't free the
node memory even after processing the BYE packet. This causes the node
memory to leak.
Hence, remove the node from Xarray list and free the node memory during
both success and failure case of ctrl_cmd_bye().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
KVM: nSVM: Triple fault if restore host CR3 fails on nested #VMEXIT
If loading L1's CR3 fails on a nested #VMEXIT, nested_svm_vmexit()
returns an error code that is ignored by most callers, and continues to
run L1 with corrupted state. A sane recovery is not possible in this
case, and HW behavior is to cause a shutdown. Inject a triple fault
instead, and do not return early from nested_svm_vmexit(). Continue
cleaning up the vCPU state (e.g. clear pending exceptions), to handle
the failure as gracefully as possible.
From the APM:
Upon #VMEXIT, the processor performs the following actions in order to
return to the host execution context:
...
if (illegal host state loaded, or exception while loading host state)
shutdown
else
execute first host instruction following the VMRUN
Remove the return value of nested_svm_vmexit(), which is mostly
unchecked anyway.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
net: qrtr: ns: Limit the maximum number of lookups
Current code does no bound checking on the number of lookups a client can
perform. Though the code restricts the lookups to local clients, there is
still a possibility of a malicious local client sending a flood of
NEW_LOOKUP messages over the same socket.
Fix this issue by limiting the maximum number of lookups to 64 globally.
Since the nameserver allows only atmost one local observer, this global
lookup count will ensure that the lookups stay within the limit.
Note that, limit of 64 is chosen based on the current platform
requirements. If requirement changes in the future, this limit can be
increased.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
mm: fix deferred split queue races during migration
migrate_folio_move() records the deferred split queue state from src and
replays it on dst. Replaying it after remove_migration_ptes(src, dst, 0)
makes dst visible before it is requeued, so a concurrent rmap-removal path
can mark dst partially mapped and trip the WARN in deferred_split_folio().
Move the requeue before remove_migration_ptes() so dst is back on the
deferred split queue before it becomes visible again.
Because migration still holds dst locked at that point, teach
deferred_split_scan() to requeue a folio when folio_trylock() fails.
Otherwise a fully mapped underused folio can be dequeued by the shrinker
and silently lost from split_queue.
[ziy@nvidia.com: move the comment]
CVSS Score
4.7
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
thermal: core: Fix thermal zone governor cleanup issues
If thermal_zone_device_register_with_trips() fails after adding
a thermal governor to the thermal zone being registered, the
governor is not removed from it as appropriate which may lead to
a memory leak.
In turn, thermal_zone_device_unregister() calls thermal_set_governor()
without acquiring the thermal zone lock beforehand which may race with
a governor update via sysfs and may lead to a use-after-free in that
case.
Address these issues by adding two thermal_set_governor() calls, one to
thermal_release() to remove the governor from the given thermal zone,
and one to the thermal zone registration error path to cover failures
preceding the thermal zone device registration.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix memory leaks in rxkad_verify_response()
Fix rxkad_verify_response() to free the ticket and the server key under all
circumstances by initialising the ticket pointer to NULL and then making
all paths through the function after the first allocation has been done go
through a single common epilogue that just releases everything - where all
the releases skip on a NULL pointer.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Add missing save/restore handling of LBR MSRs
MSR_IA32_DEBUGCTLMSR and LBR MSRs are currently not enumerated by
KVM_GET_MSR_INDEX_LIST, and LBR MSRs cannot be set with KVM_SET_MSRS. So
save/restore is completely broken.
Fix it by adding the MSRs to msrs_to_save_base, and allowing writes to
LBR MSRs from userspace only (as they are read-only MSRs) if LBR
virtualization is enabled. Additionally, to correctly restore L1's LBRs
while L2 is running, make sure the LBRs are copied from the captured
VMCB01 save area in svm_copy_vmrun_state().
Note, for VMX, this also fixes a flaw where MSR_IA32_DEBUGCTLMSR isn't
reported as an MSR to save/restore.
Note #2, over-reporting MSR_IA32_LASTxxx on Intel is ok, as KVM already
handles unsupported reads and writes thanks to commit b5e2fec0ebc3 ("KVM:
Ignore DEBUGCTL MSRs with no effect") (kvm_do_msr_access() will morph the
unsupported userspace write into a nop).
[sean: guard with lbrv checks, massage changelog]
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
net: qrtr: ns: Limit the total number of nodes
Currently, the nameserver doesn't limit the number of nodes it handles.
This can be an attack vector if a malicious client starts registering
random nodes, leading to memory exhaustion.
Hence, limit the maximum number of nodes to 64. Note that, limit of 64 is
chosen based on the current platform requirements. If requirement changes
in the future, this limit can be increased.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
scsi: sd: fix missing put_disk() when device_add(&disk_dev) fails
If device_add(&sdkp->disk_dev) fails, put_device() runs
scsi_disk_release(), which frees the scsi_disk but leaves the gendisk
referenced. The device_add_disk() error path in sd_probe() calls
put_disk(gd); call put_disk(gd) here to mirror that cleanup.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27