Linux Kernel Subsystem Memory and Logic Flaws

Out-of-bounds memory read in the Linux kernel's in-kernel SMB server (ksmbd) lets a remote, unauthenticated client leak adjacent kernel memory. The receive path applied the minimum SMB2 PDU size check only to packets with ProtocolId SMB2_PROTO_NUMBER, so a short packet carrying SMB2_TRANSFORM_PROTO_NUM slipped past validation on an SMB 2.1 connection (which offers no transform handling) and reached init_smb2_rsp_hdr(), which read past the request allocation and returned the copied fields to the client. Rated CVSS 9.1 with an EPSS of 11%; no public exploit or CISA KEV listing is indicated, so this is no public exploit identified at time of analysis.

Privilege escalation in the Linux kernel's vxlan subsystem allows a local user holding CAP_NET_ADMIN in a vxlan device's network namespace to rewrite underlay configuration in a separate, more privileged namespace where they lack that capability. The flaw in vxlan_changelink() affects multiple stable kernel branches (6.6.x, 6.12.x, 6.18.x, 7.1.x, and 7.2-rc) and is most impactful in multi-tenant container or cloud environments where vxlan devices span namespace boundaries - a common topology in Kubernetes and OpenStack deployments. With an EPSS score of 17% and no public exploit or CISA KEV listing confirmed at time of analysis, this is an elevated-risk local privilege escalation requiring prompt patching on affected containerized infrastructure.

Uninitialized memory read in the Linux kernel's libceph client library exposes stale kernel buffer contents and risks system instability on Ceph-connected hosts. The flaw exists in handle_get_version_reply(), which incorrectly uses msg->front_alloc_len - the allocated buffer size - as the decode boundary instead of msg->front.iov_len, the count of bytes actually received. A truncated MON_GET_VERSION_REPLY from a malicious or compromised Ceph monitor therefore passes the ceph_decode_need() guard and reads a second u64 from leftover bytes of a prior message, constituting an out-of-bounds read of uninitialized kernel memory. No public exploit has been identified at time of analysis, but the 16% EPSS score is elevated for a kernel library flaw and warrants prompt patching on Ceph-client deployments.

Use-after-free in the Linux kernel's btrfs filesystem driver allows a low-privileged local user to cause kernel memory corruption with full system compromise potential. Introduced by a regression in commit f86f7a75e2fb, the btrfs extent map splitting code in btrfs_drop_extent_map_range() incorrectly propagates EXTENT_FLAG_LOGGING to child split maps, which are never cleared of this flag; when the extent map shrinker later frees such a map while it remains on the inode's modified_extents list, a use-after-free is triggered. No public exploit has been identified at time of analysis, but an EPSS of 16% signals elevated exploitation probability for a local kernel UAF affecting Linux 6.8 and later across multiple stable branches.

Heap overflow in the Linux kernel's txgbe network driver enables a local attacker to write beyond an allocated heap buffer during ethtool EEPROM reads, potentially escalating to full kernel compromise on systems with Wangxun txgbe 10GbE hardware. The flaw exists because txgbe_read_eeprom_hostif() always copies round_up(length, 4) bytes into a buffer ethtool allocates to exactly length bytes, causing a 1-3 byte out-of-bounds write whenever the requested length is not 4-byte aligned. Vendor patches are available in Linux 6.19 and stable releases 7.1.6 and 7.2-rc5; no public exploit code or active exploitation has been identified at time of analysis, though the 16% EPSS score is notably elevated for a kernel driver defect.

GPU shader validation bypass in the Linux kernel's drm/vc4 driver allows local low-privileged users to rewrite validated shader bytecode after it has been approved by the GPU security validator. Specifically, vc4_gem_object_mmap() rejects writable mappings of validated shader buffer objects (BOs) but neglects to clear VM_MAYWRITE, enabling a two-step attack: map the BO read-only, then invoke mprotect() to silently upgrade the mapping to PROT_WRITE, bypassing the one-time validation check the GPU trusts unconditionally. No public exploit has been identified and no CISA KEV listing exists, but an EPSS of 17% is elevated for a local-only kernel driver issue, warranting prompt patching on affected Raspberry Pi and BCM283x-based platforms.

Missing input validation in the Linux kernel's drm/vmwgfx driver allows a low-privileged local user on a VMware guest VM to supply an arbitrary array_size value in vmw_surface_metadata via ioctl, bypassing per-Shader-Model limits and triggering out-of-bounds kernel memory access with high confidentiality, integrity, and availability impact. Affected kernel versions span 5.7 through multiple stable branches, with patches now available for 6.6.148, 6.12.101, 6.18.42, 7.1.6, and 7.2-rc5. No public exploit code or CISA KEV listing has been identified at time of analysis, though EPSS at 16% signals a meaningfully elevated probability of eventual exploitation.

Out-of-bounds read in the Linux kernel drm/amdkfd CRIU checkpoint path leaks kernel memory to userspace on systems with AMD v9 GPU hardware. The MQD control stack copy uses cp_hqd_cntl_stack_size directly from hardware registers without bounding it to the allocated Buffer Object, allowing memcpy to read past the BO into adjacent GTT memory. A local low-privileged user with access to AMD GPU compute queue checkpointing can recover sensitive kernel data; no public exploit has been identified at time of analysis, though the 15% EPSS score is above baseline for kernel information-disclosure flaws.

In the Linux kernel, the following vulnerability has been resolved: net/sched: Handle TC_ACT_REDIRECT from qdisc filter chains When a TC filter attached to a qdisc filter chain returns TC_ACT_REDIRECT (ex: via an eBPF program calling bpf_redirect() or an act_bpf action), the redirect was silently lost i.e no qdisc classify function handled TC_ACT_REDIRECT, so the packet fell through the switch and was enqueued normally instead of being redirected. This has been broken since bpf_redirect() was introduced for TC in commit 27b29f63058d ("bpf: add bpf_redirect() helper"). We got lucky for a long time because bpf_net_context was a per-CPU variable that was always available. commit 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") turned bpf_net_context into a task_struct member that is only set up by explicit callers. Without a caller setting it up, bpf_redirect() itself crashes with a NULL pointer dereference in bpf_net_ctx_get_ri(). However, even with bpf_net_context available, TC_ACT_REDIRECT from qdisc filter chains cannot be honored without adding skb_do_redirect() calls to every qdisc classify function, which would require changes across net/sched/. Isolate it to ebpf core where it belongs. Instead, add a tcf_classify_qdisc() inline helper in pkt_cls.h, as a wrapper around tcf_classify() for use by qdisc classify functions and tcf_qevent_handle(). When the classify verdict is TC_ACT_REDIRECT, the wrapper converts it to TC_ACT_SHOT, dropping the packet rather than letting it continue silently. Dropping is preferred over letting the packet through because the user immediately sees packet loss. Silently passing the packet through would hide the problem and leave the user wondering why their redirect is not working. The clsact fast path, tc_run() continues to call tcf_classify() directly and is unaffected: TC_ACT_REDIRECT is returned as-is and handled by sch_handle_egress/ingress() calling skb_do_redirect() as before.

In the Linux kernel, the following vulnerability has been resolved: btrfs: free mapping node on duplicate reloc root insert __add_reloc_root() allocates a mapping_node before inserting it into rc->reloc_root_tree. If rb_simple_insert() finds an existing entry, it returns the existing rb_node and leaves the newly allocated node unlinked. The error path then returns -EEXIST without freeing the new node. Since the node was never inserted into reloc_root_tree, the later cleanup in put_reloc_control() cannot find it either. Free the newly allocated node before returning -EEXIST. The callers currently assert that -EEXIST should not happen, so this is a defensive cleanup for an unexpected duplicate insert path. If the path is ever reached, the local allocation should still be released.

In the Linux kernel, the following vulnerability has been resolved: ovl: check access to copy_file_range source with src mounter creds Commit 5dae222a5ff0c ("vfs: allow copy_file_range to copy across devices") allowed filesystems that implement the copy_file_range() f_op to decide if they want to access cross-sb copy from/to the same fs type. The same commit added checks to verify same sb copy for filesystems that implement ->copy_file_range() and do not support cross-sb copy at the time, namely, to ceph, fuse and nfs. The two remaining fs which implement ->copy_file_range(), cifs and overlayfs started to support cross-sb copy from this time. While overlayfs does support cross-sb copy when the two underlying files are on the same base fs, the copy operation on the two real files from two different overalyfs filesystems is performed with the mounter creds of the destination overlayfs and the read permission access hook for the source file was called with the wrong creds. This could cause either deny of access to copy which would otherwise be allowed (e.g. with splice) or allow read access to file which would otherwise be denied. Fix the latter case by explicitly verifying read access to source file with the source overlayfs mounter creds. The former case remains a quirk of cross-sb overlayfs copy, but userspace could fall back to regular copy so no harm done.

In the Linux kernel, the following vulnerability has been resolved: firmware: arm_ffa: Fix NULL dereference in ffa_partition_info_get() ffa_partition_info_get() passes uuid_str directly to uuid_parse() without a NULL check. When a caller passes NULL, uuid_parse() -> __uuid_parse() -> uuid_is_valid() dereferences the pointer, causing a kernel panic: | Unable to handle kernel NULL pointer dereference at virtual address | 0000000000000040 | pc : uuid_parse+0x40/0xac | lr : ffa_partition_info_get+0x1c/0x94 [arm_ffa] Add a NULL guard before uuid_parse() so a NULL argument returns -ENODEV instead of crashing. Callers are expected to always supply a valid partition UUID, so NULL is not a supported input.

In the Linux kernel, the following vulnerability has been resolved: drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe() A hotplug or link-loss event can tear down the MST topology (setting mgr->mst_state = false and mgr->mst_primary = NULL) concurrently with a caller invoking drm_dp_mst_topology_queue_probe(). Since the check is already performed under mgr->lock, the condition is not a programming error but a valid race -- the topology was valid when the caller decided to call this function, but was torn down before the lock was acquired. Replace the drm_WARN_ON() with a graceful early return. This eliminates spurious kernel warnings and the resulting compositor crashes observed when connecting/disconnecting DP MST monitors, while keeping the correct behavior of doing nothing when MST is not active. A drm_dbg_mst() trace is added so the skipped probe remains observable under MST debug logging. The existing WARN_ON(mgr->mst_primary) in drm_dp_mst_topology_mgr_set_mst() already catches the case where the topology is initialized twice, so no diagnostic coverage is lost.

In the Linux kernel, the following vulnerability has been resolved: LoongArch: Fix address space mismatch in kexec command line lookup When searching the loaded segments for the "kexec" command line marker, the kexec_load(2) path (file_mode == 0) passes the user-space segment buffer straight to strncmp() through a bogus (char __user *) cast. This dereferences a user pointer in kernel context, which is wrong and is flagged by sparse: arch/loongarch/kernel/machine_kexec.c:84:51: sparse: incorrect type in argument 2 (different address spaces) @@ expected char const * @@ got char [noderef] __user * Here copy the marker-sized prefix of each segment into a small on-stack buffer with copy_from_user() before comparing, and skip segments that fault. The subsequent copy_from_user() that stages the full command line into the safe area is left unchanged.

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7925: fix possible NULL-pointer deref in mt7925_mcu_bss_he_tlv() mt76_connac_get_he_phy_cap routine can theoretically return NULL so check cap pointer before dereferencing it.

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: use kvzalloc to allocate struct dc struct dc has grown large over time (most of it the two inlined dc_scratch_space copies) and now sits close to the page allocator's 4 MiB contiguous allocation limit. Its actual size is not fixed by the source alone, it also depends on the compiler and the .config, so it can easily cross 4 MiB, e.g. with a newer GCC or a config change. dc_create() allocates it with kzalloc(). Once struct dc exceeds 4 MiB the request is rounded up to order 11 (8 MiB), which is above MAX_PAGE_ORDER, so the page allocator warns and returns NULL. dc_create() then fails, DM init fails and amdgpu probe aborts with -EINVAL: WARNING: mm/page_alloc.c:5197 at __alloc_frozen_pages_noprof+0x2f9/0x380 dc_create+0x38/0x660 [amdgpu] amdgpu_dm_init+0x2d9/0x510 [amdgpu] dm_hw_init+0x1b/0x90 [amdgpu] amdgpu_device_init.cold+0x150d/0x1e13 [amdgpu] amdgpu_driver_load_kms+0x19/0x80 [amdgpu] amdgpu_pci_probe+0x1e2/0x4c0 [amdgpu] dc_create() then returns NULL and DM init fails, which aborts the whole GPU init and makes amdgpu probe fail with -EINVAL ("hw_init of IP block <dm> failed -22"), leaving the display unusable. The subsequent amdgpu_irq_put() warnings during teardown are just fallout of unwinding a half-initialized device. struct dc is a software-only bookkeeping structure that is never handed to hardware DMA and is only ever kept as an opaque pointer, so it does not require physically contiguous memory. Allocate it with kvzalloc() (and free it with kvfree()) so that the allocator can fall back to vmalloc() when a contiguous allocation of that size is not available, which also avoids the MAX_PAGE_ORDER warning entirely. v2: - Rebase to amd-staging-drm-next. (cherry picked from commit 991e0516a8072f2292681c6ae98a924ab0e32575)

In the Linux kernel, the following vulnerability has been resolved: drm/imagination: Fit paired fragment job in the correct CCCB For geometry jobs with a paired fragment job, at the moment, the DRM scheduler's prepare_job() callback: - checks for internal (driver) dependencies for the geometry job; - calls into pvr_queue_get_paired_frag_job_dep() to check for external dependencies for the fragment job (the two jobs are submitted together but the common scheduler code doesn't know about it, so this needs to be done at this point in time); - calls into the prepare_job() callback again, but for the fragment job, to check its internal dependencies as well, passing the fragment job's drm_sched_job and the geometry job's drm_sched_entity / pvr_queue. The problem with the last step is that pvr_queue_prepare_job() doesn't always take the mismatched fragment job and geometry queue into account, in particular when checking whether there is space for the fragment command to be submitted, so the code ends up checking for space in the geometry (i.e. wrong) CCCB. The rest of the nested prepare_job() callback happens to work fine at the moment as the other internal dependencies are not relevant for a paired fragment job. Move the initialisation of a paired fragment job's done fence and CCCB fence to pvr_queue_get_paired_frag_job_dep(), inferring the correct queue from the fragment job itself. This fixes cases where prepare_job() wrongly assumed that there was enough space for a paired fragment job in its own CCCB, unblocking run_job(), which then returned early without writing the full sequence of commands to the CCCB. The above lead to kernel warnings such as the following and potentially job timeouts (depending on waiters on the missing commands): [ 552.421075] WARNING: drivers/gpu/drm/imagination/pvr_cccb.c:178 at pvr_cccb_write_command_with_header+0x2c4/0x330 [powervr], CPU#2: kworker/u16:5/63 [ 552.421230] Modules linked in: [ 552.421592] CPU: 2 UID: 0 PID: 63 Comm: kworker/u16:5 Tainted: G W 7.0.0-rc2-gc5d053e4dccb #39 PREEMPT [ 552.421625] Tainted: [W]=WARN [ 552.421637] Hardware name: Texas Instruments AM625 SK (DT) [ 552.421655] Workqueue: powervr-sched drm_sched_run_job_work [gpu_sched] [ 552.421744] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 552.421766] pc : pvr_cccb_write_command_with_header+0x2c4/0x330 [powervr] [ 552.421850] lr : pvr_queue_submit_job_to_cccb+0x57c/0xa74 [powervr] [ 552.421923] sp : ffff800084c47650 [ 552.421936] x29: ffff800084c47740 x28: 0000000000000df8 x27: ffff800088a77000 [ 552.421979] x26: 0000000000000030 x25: ffff800084c47680 x24: 0000000000001000 [ 552.422017] x23: ffff800084c47820 x22: 1ffff00010988ecc x21: 0000000000000008 [ 552.422055] x20: 0000000000000208 x19: ffff000006ad5a88 x18: 0000000000000000 [ 552.422093] x17: 0000000020020000 x16: 0000000000020000 x15: 0000000000000000 [ 552.422130] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 [ 552.422167] x11: 000000000000f2f2 x10: 00000000f3000000 x9 : 00000000f3f3f3f3 [ 552.422204] x8 : 00000000f2f2f200 x7 : ffff700010988ecc x6 : 0000000000000008 [ 552.422241] x5 : 0000000000000000 x4 : 1ffff0001114ee00 x3 : 0000000000000000 [ 552.422278] x2 : 0000000000000007 x1 : 0000000000000fff x0 : 000000000000002f [ 552.422316] Call trace: [ 552.422330] pvr_cccb_write_command_with_header+0x2c4/0x330 [powervr] (P) [ 552.422411] pvr_queue_submit_job_to_cccb+0x57c/0xa74 [powervr] [ 552.422486] pvr_queue_run_job+0x3a4/0x990 [powervr] [ 552.422562] drm_sched_run_job_work+0x580/0xd48 [gpu_sched] [ 552.422623] process_one_work+0x520/0x1288 [ 552.422657] worker_thread+0x3f0/0xb3c [ 552.422679] kthread+0x334/0x3d8 [ 552.422706] ret_from_fork+0x10/0x20

In the Linux kernel, the following vulnerability has been resolved: ata: sata_dwc_460ex: fix infinite loop in NCQ tag completion bit-scanning The hand-rolled bit-scanning loop in the NCQ completion path has an infinite loop bug. When tag_mask has only high bits set (e.g. 0x80000000), the inner while loop left-shifts tag_mask until it overflows to 0. At that point !(0 & 1) is always true and 0 <<= 1 stays 0, causing an infinite loop in hardirq context with a spinlock held. Replace the open-coded bit-scanning with __ffs() which correctly finds the least significant set bit and is bounded by the width of the argument.

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/gfx8: drop unecessary BUG_ON() There's no need to crash the kernel for this case. (cherry picked from commit 4d7c25208ca612b754f3bf39e9f16e725b828891)

In the Linux kernel, the following vulnerability has been resolved: hwmon: (gigabyte_waterforce) Stop device IO before calling hid_hw_stop Calling hid_hw_stop() does not stop the device IO. This results in a race condition between hid_input_report() and the point immediately following the execution of hid_device_io_start() within the driver probe function. If the probe operation fails after "io start" has been initiated, this race condition will result in a UAF vulnerability. Fix the problem by calling hid_device_io_stop() before calling hid_hw_stop().

In the Linux kernel, the following vulnerability has been resolved: serial: 8250_mid: Fix NULL function pointer dereference on DNV/ICX-D/SNR platforms Commit b1b4efea05a5 ("serial: 8250_mid: Disable DMA for selected platforms") replaced the dnv_board setup and exit callbacks with PTR_IF(false, ...), which evaluates to NULL. However, the three call sites in mid8250_probe() and mid8250_remove() unconditionally dereference these function pointers without NULL checks, causing a NULL pointer dereference (kernel oops) on any Denverton (DNV), Ice Lake Xeon D (ICX-D/CDF), or Snowridge (SNR) platform. Fix this by adding the missing NULL checks before calling the setup and exit callbacks.

In the Linux kernel, the following vulnerability has been resolved: smp: Make CSD lock acquisition atomic for debug mode Commit b0473dcd4b1d ("smp: Improve smp_call_function_single() CSD-lock diagnostics") changed smp_call_function_single() so that, when CSD lock debugging is enabled, async !wait calls use the destination CPU csd_data. That improves diagnostics, but it also removes the single-writer property that made the old csd_lock() safe: multiple CPUs can now prepare the same destination CPU CSD concurrently. csd_lock() currently waits for CSD_FLAG_LOCK to clear and then sets the bit with a non-atomic read-modify-write. Two senders can both see an unlocked CSD, set the bit, overwrite the callback fields, and enqueue the same llist node. Re-adding a node that is already the queue head can make node->next point to itself, leaving the target CPU stuck walking call_single_queue. Later synchronous work, such as a TLB shootdown, can then remain queued and trigger soft-lockup warnings or panics. Keep the single csd_lock() implementation, but when CSD lock debugging is enabled, acquire CSD_FLAG_LOCK with try_cmpxchg_acquire(). This makes the destination CPU CSD a real atomic lock in the only configuration where it can be shared by multiple remote senders, while preserving the existing non-debug fast path.