Linux Kernel threat watch

In the Linux kernel, the following vulnerability has been resolved: gfs2: fix use-after-free in gfs2_qd_dealloc gfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(), accesses the superblock object sdp through qd->qd_sbd after freeing qd. It does so to decrement sd_quota_count and wake up sd_kill_wait. However, by the time the RCU callback runs, gfs2_put_super() may have already freed sdp via free_sbd(). This can happen when gfs2_quota_cleanup() is called during unmount: it disposes of quota objects via call_rcu() and then waits on sd_kill_wait with a 60-second timeout. If the timeout expires, or if gfs2_gl_hash_clear() triggers additional qd_put() calls that schedule more RCU callbacks after the wait completes, gfs2_put_super() will proceed to free the superblock while RCU callbacks referencing it are still pending. Add an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure all pending RCU callbacks (including gfs2_qd_dealloc) have completed before the superblock is freed.

In the Linux kernel, the following vulnerability has been resolved: rpmsg: char: Fix use-after-free on probe error path rpmsg_chrdev_probe() stores the newly allocated eptdev in the default endpoint's priv pointer before calling rpmsg_chrdev_eptdev_add(). If rpmsg_chrdev_eptdev_add() then fails, its error path frees eptdev while the default endpoint may still dispatch callbacks with the stale priv pointer. Avoid publishing eptdev through the default endpoint until rpmsg_chrdev_eptdev_add() succeeds. Messages received before the priv pointer is published should be ignored by rpmsg_ept_cb(). Flow-control updates can hit rpmsg_ept_flow_cb() in the same window, so make both callbacks return success when priv is NULL.

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path In sev_dbg_crypt(), the per-iteration transfer length is bounded by the source page offset (PAGE_SIZE - s_off) but not by the destination page offset (PAGE_SIZE - d_off). When d_off > s_off, the encrypt path (__sev_dbg_encrypt_user) performs a read-modify-write using a single-page intermediate buffer (dst_tpage): 1. __sev_dbg_decrypt() expands the size to round_up(len + (d_off & 15), 16) before issuing the PSP command. If len + (d_off & 15) > PAGE_SIZE, the PSP writes beyond the end of the 4096-byte dst_tpage allocation. 2. The subsequent memcpy()/copy_from_user() into page_address(dst_tpage) + (d_off & 15) of 'len' bytes overflows by up to 15 bytes under the same condition. Trigger example: s_off = 0, d_off = 1, debug.len = PAGE_SIZE - the PSP is instructed to write round_up(4097, 16) = 4112 bytes to a 4096-byte buffer. Fix by also bounding len by (PAGE_SIZE - d_off), the same check that sev_send_update_data() already performs for its single-page guest region. ================================================================== BUG: KASAN: slab-use-after-free in sev_dbg_crypt+0x993/0xd10 [kvm_amd] Write of size 4095 at addr ff110062293bb009 by task sev_dbg_test/228214 CPU: 96 UID: 0 PID: 228214 Comm: sev_dbg_test Tainted: G U W 7.0.0-smp--5ce9b0c48211-dbg #156 PREEMPTLAZY Tainted: [U]=USER, [W]=WARN Hardware name: Google Astoria/astoria, BIOS 0.20250817.1-0 08/25/2025 Call Trace: <TASK> dump_stack_lvl+0x54/0x70 print_report+0xbc/0x260 kasan_report+0xa2/0xd0 kasan_check_range+0x25f/0x2c0 __asan_memcpy+0x40/0x70 sev_dbg_crypt+0x993/0xd10 [kvm_amd] sev_mem_enc_ioctl+0x33c/0x450 [kvm_amd] kvm_vm_ioctl+0x65d/0x6d0 [kvm] __se_sys_ioctl+0xb2/0x100 do_syscall_64+0xe8/0x870 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK> The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x7fe72b6a0 pfn:0x62293bb memcg:ff11000112827d82 flags: 0x1400000000000000(node=1|zone=1) raw: 1400000000000000 0000000000000000 dead000000000122 0000000000000000 raw: 00000007fe72b6a0 0000000000000000 00000001ffffffff ff11000112827d82 page dumped because: kasan: bad access detected Memory state around the buggy address: ff110062293bbf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff110062293bbf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ff110062293bc000: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ff110062293bc080: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ff110062293bc100: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint [sean: add sample KASAN splat, Fixes, and stable@]

In the Linux kernel, the following vulnerability has been resolved: rust: arm64: set uwtable llvm module flag for CONFIG_UNWIND_TABLES Due to a rustc bug [1] the -Cforce-unwind-tables=y flag only emits the uwtable annotation for functions, but not for the module. This means that compiler-generated functions such as 'asan.module_ctor' do not receive the uwtable annotation. When CONFIG_UNWIND_PATCH_PAC_INTO_SCS is enabled, this leads to boot failures because the dwarf information emitted for the kasan constructors is wrong, which causes the SCS boot patching code to patch the constructor in an illegal manner. Specifically, the paciasp instruction is patched, but the autiasp instruction is not. This mismatch leads to a crash when the constructor is called during boot. ================================================================== BUG: KASAN: global-out-of-bounds in do_basic_setup+0x4c/0x90 Read of size 8 at addr ffffffe3cc7eb488 by task swapper/0/1 Specifically the faulting instruction is the (*fn)() to invoke the constructor in do_ctors() of the init/main.c file. Once the fix lands in rustc, this flag can be made conditional on the rustc version. Note that passing the flag on a rustc with the fix present has no effect. [ The fix [1] has landed for Rust 1.98.0 (expected release on 2026-08-20). Thus add a version check as discussed. - Miguel ] [ Adjusted link and comment. - Miguel ]

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix out-of-bounds read in dp_get_eq_aux_rd_interval() [Why & How] The aux_rd_interval array in struct dc_lttpr_caps is declared with MAX_REPEATER_CNT - 1 (7) elements, indexed 0..6. However, the offset parameter passed to dp_get_eq_aux_rd_interval() can be as large as MAX_REPEATER_CNT (8) when a sink reports 8 LTTPR repeaters via DPCD. This leads to an out-of-bounds read of aux_rd_interval[7] when offset is 8. Fix this by growing aux_rd_interval to MAX_REPEATER_CNT elements to accommodate the full range of valid repeater counts defined by the DP spec. (cherry picked from commit a55a458a8df37a65ffda5cf721d554a8f74f6b04)

In the Linux kernel, the following vulnerability has been resolved: f2fs: protect extension_list reading with sb_lock in f2fs_sbi_show() In f2fs_sbi_show(), the extension_list, extension_count and hot_ext_count are read without holding sbi->sb_lock. If a concurrent sysfs store modifies the extension list via f2fs_update_extension_list(), the show path may read inconsistent count and array contents, potentially leading to out-of-bounds access or displaying stale data. Fix this by holding sb_lock around the entire extension list read and format operation.

In the Linux kernel, the following vulnerability has been resolved: mailbox: mailbox-test: free channels on probe error On probe error, free the previously obtained channels. This not only prevents a leak, but also UAF scenarios because the client structure will be removed nonetheless because it was allocated with devm.

In the Linux kernel, the following vulnerability has been resolved: mailbox: mailbox-test: don't free the reused channel The RX channel can be aliased to the TX channel if it has a different MMIO. This special case needs to be handled when freeing the channels otherwise a double-free occurs.

In the Linux kernel, the following vulnerability has been resolved: idpf: fix double free and use-after-free in aux device error paths When auxiliary_device_add() fails in idpf_plug_vport_aux_dev() or idpf_plug_core_aux_dev(), the err_aux_dev_add label calls auxiliary_device_uninit() and falls through to err_aux_dev_init. The uninit call will trigger put_device(), which invokes the release callback (idpf_vport_adev_release / idpf_core_adev_release) that frees iadev. The fall-through then reads adev->id from the freed iadev for ida_free() and double-frees iadev with kfree(). Free the IDA slot and clear the back-pointer before uninit, while adev is still valid, then return immediately. Commit 65637c3a1811 ("idpf: fix UAF in RDMA core aux dev deinitialization") fixed the same use-after-free in the matching unplug path in this file but missed both probe error paths.

In the Linux kernel, the following vulnerability has been resolved: erofs: fix use-after-free on sbi->sync_decompress z_erofs_decompress_kickoff() can race with filesystem unmount, causing a use-after-free on sbi->sync_decompress. When I/O completes, z_erofs_endio() calls z_erofs_decompress_kickoff() to queue z_erofs_decompressqueue_work() asynchronously. Then, after all folios are unlocked, unmount workflow can proceed and sbi will be freed before accessing to sbi->sync_decompress. Thread (unmount) I/O completion kworker queue_work z_erofs_decompressqueue_work (all folios are unlocked) cleanup_mnt .. erofs_kill_sb erofs_sb_free kfree(sbi) access sbi->sync_decompress // UAF!!

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: MGMT: validate advertising TLV before type checks tlv_data_is_valid() reads each advertising data field length from data[i], then inspects data[i + 1] for managed EIR types before checking that the current field still fits inside the supplied buffer. A malformed field whose length byte is the last byte of the buffer can therefore make the parser read one byte past the advertising data. KASAN reported the following when a malformed MGMT_OP_ADD_ADVERTISING request reached that path: BUG: KASAN: vmalloc-out-of-bounds in tlv_data_is_valid() Read of size 1 Call trace: tlv_data_is_valid() add_advertising() hci_mgmt_cmd() hci_sock_sendmsg() Move the existing element-length check before any type-octet inspection so each non-empty element is proven to contain its type byte before the parser looks at data[i + 1].

In the Linux kernel, the following vulnerability has been resolved: net: ibm: emac: Fix use-after-free during device removal The driver was using devm_register_netdev() which causes unregister_netdev() to be deferred until the devres cleanup phase, which runs after emac_remove() returns. This creates a use-after-free window where: 1. emac_remove() is called, which tears down hardware (cancels work, detaches modules, unregisters from MAL) 2. emac_remove() returns 3. devres cleanup runs and finally calls unregister_netdev() During step 3, the network stack might still process packets, triggering emac_irq(), emac_poll(), or other handlers that access now-freed hardware resources (dev->emacp, dev->mal, etc.). Fix this by replacing devm_register_netdev() with manual register_netdev() and calling unregister_netdev() at the beginning of emac_remove(), before any hardware teardown. This ensures the network device is fully stopped and unregistered before hardware resources are released. The change is safe because: - dev->ndev is assigned very early in probe (before any error paths that could bypass emac_remove) - platform_set_drvdata() is only called after successful registration, so emac_remove() only runs for fully registered devices - unregister_netdev() is idempotent and safe to call on any registered device

In the Linux kernel, the following vulnerability has been resolved: netdev: fix double-free in netdev_nl_bind_rx_doit() Sashiko flags that genlmsg_reply() always consumes the skb. The error path calls nlmsg_free(rsp) so we can't jump directly to it. Let's not unbind, just propagate the error to the user. This is the typical way of handling genlmsg_reply() failures. They shouldn't happen unless user does something silly like calling the kernel with an already-full rcvbuf.

In the Linux kernel, the following vulnerability has been resolved: USB: serial: io_ti: fix heap overflow in build_i2c_fw_hdr() build_i2c_fw_hdr() allocates a fixed-size buffer of (16*1024 - 512) + sizeof(struct ti_i2c_firmware_rec) bytes, then copies le16_to_cpu(img_header->Length) bytes into it without validating that Length fits within the available space after the firmware record header. img_header->Length is a __le16 from the firmware file and can be up to 65535. check_fw_sanity() validates the total firmware size but not img_header->Length specifically. Fix by rejecting images where img_header->Length exceeds the available destination space.

In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs: fix buffer over-read in rtw_update_protection rtw_update_protection() is called with a pointer offset into the ies buffer but the full ie_length is passed, causing a potential buffer over-read.

In the Linux kernel, the following vulnerability has been resolved: net: phonet: free phonet_device after RCU grace period phonet_device_destroy() removes a phonet_device from the per-net device list with list_del_rcu(), but frees it immediately. RCU readers walking the same list can still hold a pointer to the object after it has been removed, leading to a slab-use-after-free. Use kfree_rcu(), matching the lifetime rule already used by phonet_address_del() for the same object type.

In the Linux kernel, the following vulnerability has been resolved: nvmem: core: fix use-after-free bugs in error paths Fix several instances of error paths in which we call __nvmem_device_put() - which may end up freeing the underlying memory and other resources - and then keep on using the nvmem structure. Always put the reference to the nvmem device as the last step before returning the error code.

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Bound root directory content to block size __tb_property_parse_dir() does not check that content_offset + content_len fits within block_len for the root directory case. When rootdir->length equals or exceeds block_len - 2, the entry loop reads past the allocated property block. Add a bounds check after computing content_offset and content_len to reject directories whose content extends past the block.

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Clamp XDomain response data copy to allocation size tb_xdp_properties_request() derives the per-packet copy length from the response header without checking that it fits in the previously allocated data buffer. A malicious peer can set its length field larger than the declared data_length, causing memcpy to write past the kcalloc allocation. Clamp the per-packet copy length so that the cumulative offset never exceeds data_len.

In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: Fix buffer overflow in SDMA queue checkpoint/restore on GFX11 The v11 MQD manager incorrectly assigned the CP-compute variants of checkpoint_mqd/restore_mqd for KFD_MQD_TYPE_SDMA queues. These functions use sizeof(struct v11_compute_mqd) (2048 bytes) instead of sizeof(struct v11_sdma_mqd) (512 bytes), causing a 1536-byte overflow. During CRIU checkpoint of an SDMA queue on Navi3x: - checkpoint_mqd() reads 2048 bytes from a 512-byte SDMA MQD buffer, leaking 1536 bytes of adjacent GTT memory to userspace During CRIU restore: - restore_mqd() writes 2048 bytes into a 512-byte SDMA MQD buffer, corrupting 1536 bytes of adjacent GTT memory (often the ring buffer or neighboring MQDs) This is a copy-paste regression unique to v11. All other ASIC backends (cik, vi, v9, v10, v12) correctly use the SDMA-specific variants. Add checkpoint_mqd_sdma() and restore_mqd_sdma() functions that properly handle the smaller v11_sdma_mqd structure, matching the pattern used in other MQD managers. (cherry picked from commit 6fa41db7ffdec97d62433adf03b7b9b759af8c2c)