Linux Kernel 4.19.70 Released
Linux kernel 4.19.70 is a stable release containing 95 fixes and improvements across multiple subsystems. This release addresses critical issues in audio, networking, storage, virtualization, DMA handling, and various device drivers.
Major Fixes
Audio and Sound
ALSA USB Audio Improvements
The release includes several USB audio enhancements. A quirk was added for Behringer UFX1604 to apply implicit feedback like the UFX1204 model, fixing noisy playback issues. An invalid NULL pointer check in snd_emuusb_set_samplerate() was corrected—the check was occurring after a container_of() call which always returns a valid pointer, so the validation was moved earlier in the function.
A critical fix prevents potential concurrent access to deleted audio sequencer pools. The snd_seq_ioctl_get_client_pool() function now properly acquires locks before accessing the input pool, preventing crashes when the pool is resized via ioctl while being accessed.
HDA Codec Fixes
An inverted logic bug in Conexant GPIO mic mute LED handling was fixed. The “enabled” parameter historically referred to device input/output state, not the LED indicator itself. After LED helper function changes, the logic became inverted, causing the LED to display opposite state. This has been corrected in cxt_update_gpio_led().
Networking
TCP and Socket Handling
A race condition in TCP socket handling was addressed where EPOLLOUT events could be missed under memory pressure. The fix ensures SOCK_NOSPACE is always set when -EAGAIN is returned, regardless of blocking mode status. This mirrors proper behavior in blocking and non-blocking scenarios.
SMC sockets now correctly raise EPOLLOUT by setting SOCK_NOSPACE on write timeout for both blocking sockets with SO_SNDTIMEO and non-blocking sockets, ensuring edge-triggered epoll() mode works reliably.
IPv4 and IPv6
A null pointer dereference in __icmp_send() was fixed. The rt->dst.dev can be NULL with tunnel metadata mode (GRE, etc.), causing crashes. The fix uses skb->dev as a fallback when rt->dst.dev is unavailable.
IPv6 route type handling now defaults to RTN_UNICAST when not explicitly set, restoring pre-4.19 behavior. This fixes issues where routes were installed with type 0 (RTN_UNSPEC) instead of unicast, particularly affecting legacy ioctl-based interfaces and netlink tools that don’t require rtm_type.
IPv6 multicast address addition is now allowed when the IFA_F_MCAUTOJOIN flag is set, fixing a regression where multicast addresses were always rejected in ipv6_add_addr() even with the proper flag.
TLS Socket Issues
TLS socket closing now properly restores the original sk_write_space callback instead of leaving a dangling pointer. When TX mode is disabled, ctx->sk_write_space is NULL, so the fix checks if the current pointer is the TLS-specific one before attempting restoration.
A return value bug in tls_sw_sendmsg() and tls_sw_sendpage() was corrected where tls_complete_pending_work() failures were being silently ignored.
Storage and Block Devices
NVMe Multipath and Device Handling
A critical deadlock was fixed that occurred when passthrough commands were sent to multipath devices. The issue involved freezing namespace request queues without freezing the corresponding mpath node queue, causing I/O to block indefinitely. The fix freezes all subsystem namespace head request queues before executing passthrough commands.
NVMe async probe and device removal now synchronize properly, preventing races where a controller in NEW state could fail to transition to DELETING during removal.
The nvme-loop driver now flushes nvme_delete_wq when removing ports, ensuring controllers being deleted won’t access freed port memory.
Multipath namespace gendisk revalidation was fixed to actually update visible block device capacity, enabling online filesystem expansion on multipath NVMe devices.
USB Storage
Realtek USB storage auto-delink support is now whitelisted for specific device IDs (0x0138, 0x0158, 0x0159) rather than unconditionally enabled, preventing breakage of newer devices. The module parameter documentation was clarified to reflect that auto_delink_en=false lets firmware control delink rather than disabling it completely.
A new JMS567 revision (0x0117) was added to the device quirks list due to identical issues as earlier revisions.
Virtualization and Hypervisor
KVM Fixes
ARM VGIC handling was corrected to treat SGI (Software Generated Interrupt) bits in pending registers as write-ignore per ARM specifications.
A potential deadlock in the VGIC was fixed where merge_final() in list_sort() could cause comparison callbacks to be called with identical elements, deadlocking in vgic_irq_cmp() when the active pending list exceeded 256 entries.
PPC Book3S guest-to-user translation error handling was fixed to properly unlock SRCU and rmap locks during early handler exits.
x86 KVM now prevents RIP advancement and single-step injection when instruction emulation faults, fixing infinite loops when invalid SYSCALL instructions with EFLAGS.TF=1 are encountered.
KVM x86 APIC logical destination map population now correctly skips when APIC is not software-enabled, preventing invalid map entries from overwriting valid ones during kdump initialization.
Xen Hypervisor
Memory leaks in xen/blkback were fixed by properly cleaning up allocated requests and regions when xen_blkif_map() fails during probe.
DMA and Device Bus
DMA Handling
IOMMU DMA scatterlist segment merging was fixed to handle devices with max_segment_size=UINT_MAX. Unsigned integer overflow during length checking caused bogus truncated dma_length values for merged segments exceeding 4GB.
STM32 MDMA interrupt handler now properly checks for NULL channel pointer before dereferencing it in error messages.
OMAP DMA frame index register handling was corrected—the FI value was incorrectly calculated, missing the “minus 1” required by OMAP TRM specifications. The fix applies to both omap-dma.c and removes the workaround from omap_vout_vrfb.c.
Device Bus and Control
HISI LPC bus driver now properly cleans up logical PIO ranges and removes child devices on driver removal, preventing use-after-free crashes and memory leaks.
Logical PIO range registration code was restructured to avoid overlaps when unregistering regions, and proper RCU locking was added around list traversal operations.
USB Host and Gadget
USB Host Controller
OHCI shutdown now properly synchronizes with interrupt handlers by holding spin locks, preventing race conditions where interrupts could re-enable processing after shutdown on certain hardware.
xHCI R-Car controller now properly matches “renesas” (not “renensas”) in compatible strings, fixing coverage for RZ/G1M and RZ/G1N platforms.
XHCI extended capability drivers now work correctly by using managed device resources in PCI probe, ensuring proper resource cleanup order on removal.
Faraday FOTG2 host controller restarts after port reset on Gemini SoC to work around hardware stalling issues.
USB Gadget
Mass storage gadget race conditions between fsg_disable() and fsg_set_alt() were fixed by using a state argument instead of new_fsg pointer, ensuring consistency between dequeued state and the observed value.
Composite gadget driver now clears the suspended flag on reset or disconnect, properly handling out-of-suspend transitions with reconnection.
CDC-WDM driver race between write and disconnect was fixed by checking both WDM_IN_USE and WDM_DISCONNECTED flags in flush() and never clearing WDM_IN_USE.
Cryptography and Security
Crypto Accelerators
CCP (AMD Secure Processor) device handling was fixed to check for valid pointer before accessing structure members during suspend/resume when the device is unconfigured.
VMCI doorbell reference counting was corrected to release resources if schedule_work() indicates work is already queued, preventing the reference from being held indefinitely.
Graphics and Display
Intel i915 Graphics
DMA segment size is now properly configured to UINT_MAX with dma_set_max_seg_size(), silencing spurious DMA-API debug warnings on kernels with CONFIG_DMA_API_DEBUG_SG.
Broadwell EU computation was fixed—subslice_mask is indexed by slice, not subslice.
GGTT deballoon in Linux guest VMs now checks for valid drm_mm_node before removal, preventing NULL pointer dereference when unloading the i915 driver.
AMD GPU
Dell Latitude 5495 now correctly uses ATPX for dGPU power control instead of _PR3, saving approximately 5W when the dGPU is runtime-suspended.
AST Display Driver
Standard VGA I/O decode is now disabled during probe to prevent concurrent access from other threads, avoiding system hangs during reboot tests.
Display Bridges
TFP410 bridge get_modes() now properly frees EDID blob allocated by drm_get_edid(), fixing memory leaks.
Core Kernel and Tracing
Ftrace and Dynamic Tracing
Function probe registration now checks for successful hash allocation before dereferencing, preventing NULL pointer issues.
The race between adding function probes and reading existing probes is now documented with appropriate comments, and probes with EMPTY_HASH are properly handled.
t_probe_next() now safely handles NULL filter_hash when probes are being initialized, preventing crashes during filter file reads concurrent with probe registration.
Kernel Compilation and Build
Build Fixes
zsmalloc now builds correctly with CONFIG_COMPACTION=n by fixing function call compatibility.
Perf and Monitoring
Performance Monitoring
x86 APIC Local Destination Register (LDR) is now properly cleared during cleanup, fixing destination mapping corruption in 32-bit KVM guests during kdump initialization.
bigsmp APIC mode no longer incorrectly initializes LDR and DFR when physical destination mode is in use, fixing APIC calibration hangs in kdump.
Debugging and Instrumentation
Intel Trace Hub
Tiger Lake Point and additional Lewisburg PCH device IDs are now supported for Intel Trace Hub functionality.
STM Class
Double-free in stm_source_register_device() error path was fixed by removing unnecessary kfree() call that would duplicate the release from put_device().
Architecture-Specific Fixes
x86 Architecture
Spectre v1 mitigation in ptrace was correctly backported, fixing an incomplete merge from upstream.
32-bit userspace mode detection on 64-bit kernels now uses user_64bit_mode() instead of in_ia32_syscall(), fixing uretprobe crashes by correctly preserving return addresses.
ARM64 Architecture
ARM64 page granule sizes are no longer treated as strict mismatches, allowing systems with heterogeneous CPU granule support (like Amlogic S922X) to boot without kernel taint.
File Systems
AFS (Andrew File System)
afs_d_revalidate() no longer unconditionally updates d_fsdata without holding locks—it now only updates when the directory version actually changes.
afs_put_read() now safely handles NULL req->pages before array access, preventing null pointer dereference.
AFS volume location entry parsing now uses the correct index for populating return site arrays, fixing EDESTADDRREQ errors.
CB.ProbeUuid RPC handler now replies correctly with empty response for success (not integer 0), preventing fileserver association errors and lost callbacks.
Device Drivers and Miscellaneous
Memory Management
zsmalloc race condition during pool destruction is now properly handled with correct build support.
I2C Drivers
Emev2 and R-Car I2C slave support now properly synchronizes interrupt handlers before clearing slave device pointers, preventing races during unregistration.
AMD Family 16h Model 30h SMBus port selection now works correctly by checking PCI revision ID to distinguish between Bolton and Family 16h devices.
Watchdog
BCM2835 watchdog module autoloading is restored via proper device alias after MFD migration.
Display and Audio Support
MEI (Management Engine Interface) adds Tiger Lake Point device ID support.
HyperV Tools
KVP and VSS daemon exit codes are now correct (0 for --help), and lsvmbus Python code follows pep8/flake8 style guidelines.
Miscellaneous Device Support
Panelboard auxdisplay driver now properly cleans up scan timer when misc_register() fails.
SoundWire Cadence master controller register definitions for INTSTAT0/INTSTAT1 and SLAVE_STATE are corrected.
Summary
Linux 4.19.70 represents a focused stable release addressing critical bugs across audio, networking, storage, virtualization, and device driver subsystems. The fixes emphasize proper synchronization, resource cleanup, null pointer safety, and hardware compatibility, making this a recommended update for production systems running the 4.19 LTS branch.