Linux: >> Linux Kernel >> 5.15.191 Security Vulnerabilities
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
0.002
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
tcp: call sk_data_ready() after listener migration
When inet_csk_listen_stop() migrates an established child socket from
a closing listener to another socket in the same SO_REUSEPORT group,
the target listener gets a new accept-queue entry via
inet_csk_reqsk_queue_add(), but that path never notifies the target
listener's waiters. A nonblocking accept() still works because it
checks the queue directly, but poll()/epoll_wait() waiters and
blocking accept() callers can also remain asleep indefinitely.
Call READ_ONCE(nsk->sk_data_ready)(nsk) after a successful migration
in inet_csk_listen_stop().
However, after inet_csk_reqsk_queue_add() succeeds, the ref acquired
in reuseport_migrate_sock() is effectively transferred to
nreq->rsk_listener. Another CPU can then dequeue nreq via accept()
or listener shutdown, hit reqsk_put(), and drop that listener ref.
Since listeners are SOCK_RCU_FREE, wrap the post-queue_add()
dereferences of nsk in rcu_read_lock()/rcu_read_unlock(), which also
covers the existing sock_net(nsk) access in that path.
The reqsk_timer_handler() path does not need the same changes for two
reasons: half-open requests become readable only after the final ACK,
where tcp_child_process() already wakes the listener; and once nreq is
visible via inet_ehash_insert(), the success path no longer touches
nsk directly.
CVSS Score
7.8
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
0.002
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
ALSA: caiaq: Handle probe errors properly
The probe procedure of setup_card() in caiaq driver doesn't treat the
error cases gracefully, e.g. the error from snd_card_register() calls
snd_card_free() but continues. This would lead to a UAF for the
further calls like snd_usb_caiaq_control_init(), as Berk suggested in
another patch in the link below.
However, the problem is not only that; in general, this function drops
the all error handlings (as it's a void function) although its caller
can propagate an error to snd_probe(), which eventually calls
snd_card_free() as a proper error path. That said, we should treat
each error case in setup_card(), and just return the error code
promptly, which is then handled later as a fatal error in snd_probe().
This patch achieves it by changing the setup_card() to return an error
code. Also, the superfluous snd_card_free() call is removed, too.
Note that card->private_free can be set still safely at returning an
error. All called functions in card_free() have checks of the
unassigned resources or NULL checks.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau: fix u32 overflow in pushbuf reloc bounds check
nouveau_gem_pushbuf_reloc_apply() validates each relocation with
if (r->reloc_bo_offset + 4 > nvbo->bo.base.size)
but reloc_bo_offset is __u32 (uapi/drm/nouveau_drm.h) and the integer
literal 4 promotes to unsigned int, so the addition is performed in 32
bits and wraps before the comparison against the size_t bo size.
Cast to u64 so the addition happens in 64-bit arithmetic.
[ Add Fixes: tag. - Danilo ]
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
PCI: endpoint: pci-epf-ntb: Remove duplicate resource teardown
epf_ntb_epc_destroy() duplicates the teardown that the caller is
supposed to do later. This leads to an oops when .allow_link fails or
when .drop_link is performed. Remove the helper.
Also drop pci_epc_put(). EPC device refcounting is tied to configfs EPC
group lifetime, and pci_epc_put() in the .drop_link path is sufficient.
CVSS Score
5.5
EPSS Score
0.002
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
0.002
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap()
Some crafted images can have illegal (!partial_decoding &&
m_llen < m_plen) extents, and the LZ4 inplace decompression path
can be wrongly hit, but it cannot handle (outpages < inpages)
properly: "outpages - inpages" wraps to a large value and
the subsequent rq->out[] access reads past the decompressed_pages
array.
However, such crafted cases can correctly result in a corruption
report in the normal LZ4 non-inplace path.
Let's add an additional check to fix this for backporting.
Reproducible image (base64-encoded gzipped blob):
H4sIAJGR12kCA+3SPUoDQRgG4MkmkkZk8QRbRFIIi9hbpEjrHQI5ghfwCN5BLCzTGtLbBI+g
dilSJo1CnIm7GEXFxhT6PDDwfrs73/ywIQD/1ePD4r7Ou6ETsrq4mu7XcWfj++Pb58nJU/9i
PNtbjhan04/9GtX4qVYc814WDqt6FaX5s+ZwXXeq52lndT6IuVvlblytLMvh4Gzwaf90nsvz
2DF/21+20T/ldgp5s1jXRaN4t/8izsy/OUB6e/Qa79r+JwAAAAAAAL52vQVuGQAAAP6+my1w
ywAAAAAAAADwu14ATsEYtgBQAAA=
$ mount -t erofs -o cache_strategy=disabled foo.erofs /mnt
$ dd if=/mnt/data of=/dev/null bs=4096 count=1
CVSS Score
7.1
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix conn-level packet handling to unshare RESPONSE packets
The security operations that verify the RESPONSE packets decrypt bits of it
in place - however, the sk_buff may be shared with a packet sniffer, which
would lead to the sniffer seeing an apparently corrupt packet (actually
decrypted).
Fix this by handing a copy of the packet off to the specific security
handler if the packet was cloned.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
ext2: reject inodes with zero i_nlink and valid mode in ext2_iget()
ext2_iget() already rejects inodes with i_nlink == 0 when i_mode is
zero or i_dtime is set, treating them as deleted. However, the case of
i_nlink == 0 with a non-zero mode and zero dtime slips through. Since
ext2 has no orphan list, such a combination can only result from
filesystem corruption - a legitimate inode deletion always sets either
i_dtime or clears i_mode before freeing the inode.
A crafted image can exploit this gap to present such an inode to the
VFS, which then triggers WARN_ON inside drop_nlink() (fs/inode.c) via
ext2_unlink(), ext2_rename() and ext2_rmdir():
WARNING: CPU: 3 PID: 609 at fs/inode.c:336 drop_nlink+0xad/0xd0 fs/inode.c:336
CPU: 3 UID: 0 PID: 609 Comm: syz-executor Not tainted 6.12.77+ #1
Call Trace:
<TASK>
inode_dec_link_count include/linux/fs.h:2518 [inline]
ext2_unlink+0x26c/0x300 fs/ext2/namei.c:295
vfs_unlink+0x2fc/0x9b0 fs/namei.c:4477
do_unlinkat+0x53e/0x730 fs/namei.c:4541
__x64_sys_unlink+0xc6/0x110 fs/namei.c:4587
do_syscall_64+0xf5/0x220 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
WARNING: CPU: 0 PID: 646 at fs/inode.c:336 drop_nlink+0xad/0xd0 fs/inode.c:336
CPU: 0 UID: 0 PID: 646 Comm: syz.0.17 Not tainted 6.12.77+ #1
Call Trace:
<TASK>
inode_dec_link_count include/linux/fs.h:2518 [inline]
ext2_rename+0x35e/0x850 fs/ext2/namei.c:374
vfs_rename+0xf2f/0x2060 fs/namei.c:5021
do_renameat2+0xbe2/0xd50 fs/namei.c:5178
__x64_sys_rename+0x7e/0xa0 fs/namei.c:5223
do_syscall_64+0xf5/0x220 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
WARNING: CPU: 0 PID: 634 at fs/inode.c:336 drop_nlink+0xad/0xd0 fs/inode.c:336
CPU: 0 UID: 0 PID: 634 Comm: syz-executor Not tainted 6.12.77+ #1
Call Trace:
<TASK>
inode_dec_link_count include/linux/fs.h:2518 [inline]
ext2_rmdir+0xca/0x110 fs/ext2/namei.c:311
vfs_rmdir+0x204/0x690 fs/namei.c:4348
do_rmdir+0x372/0x3e0 fs/namei.c:4407
__x64_sys_unlinkat+0xf0/0x130 fs/namei.c:4577
do_syscall_64+0xf5/0x220 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
Extend the existing i_nlink == 0 check to also catch this case,
reporting the corruption via ext2_error() and returning -EFSCORRUPTED.
This rejects the inode at load time and prevents it from reaching any
of the namei.c paths.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-05-27