Linux: >> Linux Kernel >> 6.6.48 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: clean up FDB, MDB, VLAN entries on unbind
As explained in many places such as commit b117e1e8a86d ("net: dsa:
delete dsa_legacy_fdb_add and dsa_legacy_fdb_del"), DSA is written given
the assumption that higher layers have balanced additions/deletions.
As such, it only makes sense to be extremely vocal when those
assumptions are violated and the driver unbinds with entries still
present.
But Ido Schimmel points out a very simple situation where that is wrong:
https://lore.kernel.org/netdev/ZDazSM5UsPPjQuKr@shredder/
(also briefly discussed by me in the aforementioned commit).
Basically, while the bridge bypass operations are not something that DSA
explicitly documents, and for the majority of DSA drivers this API
simply causes them to go to promiscuous mode, that isn't the case for
all drivers. Some have the necessary requirements for bridge bypass
operations to do something useful - see dsa_switch_supports_uc_filtering().
Although in tools/testing/selftests/net/forwarding/local_termination.sh,
we made an effort to popularize better mechanisms to manage address
filters on DSA interfaces from user space - namely macvlan for unicast,
and setsockopt(IP_ADD_MEMBERSHIP) - through mtools - for multicast, the
fact is that 'bridge fdb add ... self static local' also exists as
kernel UAPI, and might be useful to someone, even if only for a quick
hack.
It seems counter-productive to block that path by implementing shim
.ndo_fdb_add and .ndo_fdb_del operations which just return -EOPNOTSUPP
in order to prevent the ndo_dflt_fdb_add() and ndo_dflt_fdb_del() from
running, although we could do that.
Accepting that cleanup is necessary seems to be the only option.
Especially since we appear to be coming back at this from a different
angle as well. Russell King is noticing that the WARN_ON() triggers even
for VLANs:
https://lore.kernel.org/netdev/Z_li8Bj8bD4-BYKQ@shell.armlinux.org.uk/
What happens in the bug report above is that dsa_port_do_vlan_del() fails,
then the VLAN entry lingers on, and then we warn on unbind and leak it.
This is not a straight revert of the blamed commit, but we now add an
informational print to the kernel log (to still have a way to see
that bugs exist), and some extra comments gathered from past years'
experience, to justify the logic.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: mv88e6xxx: fix -ENOENT when deleting VLANs and MST is unsupported
Russell King reports that on the ZII dev rev B, deleting a bridge VLAN
from a user port fails with -ENOENT:
https://lore.kernel.org/netdev/Z_lQXNP0s5-IiJzd@shell.armlinux.org.uk/
This comes from mv88e6xxx_port_vlan_leave() -> mv88e6xxx_mst_put(),
which tries to find an MST entry in &chip->msts associated with the SID,
but fails and returns -ENOENT as such.
But we know that this chip does not support MST at all, so that is not
surprising. The question is why does the guard in mv88e6xxx_mst_put()
not exit early:
if (!sid)
return 0;
And the answer seems to be simple: the sid comes from vlan.sid which
supposedly was previously populated by mv88e6xxx_vtu_get().
But some chip->info->ops->vtu_getnext() implementations do not populate
vlan.sid, for example see mv88e6185_g1_vtu_getnext(). In that case,
later in mv88e6xxx_port_vlan_leave() we are using a garbage sid which is
just residual stack memory.
Testing for sid == 0 covers all cases of a non-bridge VLAN or a bridge
VLAN mapped to the default MSTI. For some chips, SID 0 is valid and
installed by mv88e6xxx_stu_setup(). A chip which does not support the
STU would implicitly only support mapping all VLANs to the default MSTI,
so although SID 0 is not valid, it would be sufficient, if we were to
zero-initialize the vlan structure, to fix the bug, due to the
coincidence that a test for vlan.sid == 0 already exists and leads to
the same (correct) behavior.
Another option which would be sufficient would be to add a test for
mv88e6xxx_has_stu() inside mv88e6xxx_mst_put(), symmetric to the one
which already exists in mv88e6xxx_mst_get(). But that placement means
the caller will have to dereference vlan.sid, which means it will access
uninitialized memory, which is not nice even if it ignores it later.
So we end up making both modifications, in order to not rely just on the
sid == 0 coincidence, but also to avoid having uninitialized structure
fields which might get temporarily accessed.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
RDMA/core: Silence oversized kvmalloc() warning
syzkaller triggered an oversized kvmalloc() warning.
Silence it by adding __GFP_NOWARN.
syzkaller log:
WARNING: CPU: 7 PID: 518 at mm/util.c:665 __kvmalloc_node_noprof+0x175/0x180
CPU: 7 UID: 0 PID: 518 Comm: c_repro Not tainted 6.11.0-rc6+ #6
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:__kvmalloc_node_noprof+0x175/0x180
RSP: 0018:ffffc90001e67c10 EFLAGS: 00010246
RAX: 0000000000000100 RBX: 0000000000000400 RCX: ffffffff8149d46b
RDX: 0000000000000000 RSI: ffff8881030fae80 RDI: 0000000000000002
RBP: 000000712c800000 R08: 0000000000000100 R09: 0000000000000000
R10: ffffc90001e67c10 R11: 0030ae0601000000 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000000
FS: 00007fde79159740(0000) GS:ffff88813bdc0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000180 CR3: 0000000105eb4005 CR4: 00000000003706b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ib_umem_odp_get+0x1f6/0x390
mlx5_ib_reg_user_mr+0x1e8/0x450
ib_uverbs_reg_mr+0x28b/0x440
ib_uverbs_write+0x7d3/0xa30
vfs_write+0x1ac/0x6c0
ksys_write+0x134/0x170
? __sanitizer_cov_trace_pc+0x1c/0x50
do_syscall_64+0x50/0x110
entry_SYSCALL_64_after_hwframe+0x76/0x7e
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
fbdev: omapfb: Add 'plane' value check
Function dispc_ovl_setup is not intended to work with the value OMAP_DSS_WB
of the enum parameter plane.
The value of this parameter is initialized in dss_init_overlays and in the
current state of the code it cannot take this value so it's not a real
problem.
For the purposes of defensive coding it wouldn't be superfluous to check
the parameter value, because some functions down the call stack process
this value correctly and some not.
For example, in dispc_ovl_setup_global_alpha it may lead to buffer
overflow.
Add check for this value.
Found by Linux Verification Center (linuxtesting.org) with SVACE static
analysis tool.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: handle amdgpu_cgs_create_device() errors in amd_powerplay_create()
Add error handling to propagate amdgpu_cgs_create_device() failures
to the caller. When amdgpu_cgs_create_device() fails, release hwmgr
and return -ENOMEM to prevent null pointer dereference.
[v1]->[v2]: Change error code from -EINVAL to -ENOMEM. Free hwmgr.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: debugfs hang_hws skip GPU with MES
debugfs hang_hws is used by GPU reset test with HWS, for MES this crash
the kernel with NULL pointer access because dqm->packet_mgr is not setup
for MES path.
Skip GPU with MES for now, MES hang_hws debugfs interface will be
supported later.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: Fix mode1 reset crash issue
If HW scheduler hangs and mode1 reset is used to recover GPU, KFD signal
user space to abort the processes. After process abort exit, user queues
still use the GPU to access system memory before h/w is reset while KFD
cleanup worker free system memory and free VRAM.
There is use-after-free race bug that KFD allocate and reuse the freed
system memory, and user queue write to the same system memory to corrupt
the data structure and cause driver crash.
To fix this race, KFD cleanup worker terminate user queues, then flush
reset_domain wq to wait for any GPU ongoing reset complete, and then
free outstanding BOs.
CVSS Score
7.8
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
btrfs: harden block_group::bg_list against list_del() races
As far as I can tell, these calls of list_del_init() on bg_list cannot
run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(),
as they are in transaction error paths and situations where the block
group is readonly.
However, if there is any chance at all of racing with mark_bg_unused(),
or a different future user of bg_list, better to be safe than sorry.
Otherwise we risk the following interleaving (bg_list refcount in parens)
T1 (some random op) T2 (btrfs_mark_bg_unused)
!list_empty(&bg->bg_list); (1)
list_del_init(&bg->bg_list); (1)
list_move_tail (1)
btrfs_put_block_group (0)
btrfs_delete_unused_bgs
bg = list_first_entry
list_del_init(&bg->bg_list);
btrfs_put_block_group(bg); (-1)
Ultimately, this results in a broken ref count that hits zero one deref
early and the real final deref underflows the refcount, resulting in a WARNING.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
In the Linux kernel, the following vulnerability has been resolved:
scsi: st: Fix array overflow in st_setup()
Change the array size to follow parms size instead of a fixed value.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09
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.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-05-09