Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix busy dentry warning on unmount after DIO

Commit c68337442f03 ("cifs: Fix busy dentry used after unmounting") fixed the issue in cifs where deferred close of a file led to a dentry reference count not being released in umount, by flushing deferredclose_wq in cifs_kill_sb() to solve it.

However, the cifs DIO path suffers from the same busy-dentry problem caused by a delayed dentry reference-count release:

[dio] [cifsd] [close + umount] netfs_unbuffered_write_iter_locked ... cifs_demultiplex_thread netfs_unbuffered_write cifs_issue_write netfs_wait_for_in_progress_stream [1] ... netfs_write_subrequest_terminated netfs_subreq_clear_in_progress netfs_wake_collector // wake [1] netfs_put_subrequest netfs_put_request queue_work(system_dfl_wq, xxx) [2] // dio write return cifs_close _cifsFileInfo_put // cfile->count 2->1 --cfile->count [3]

// umount cifs_kill_sb kill_anon_super // warning triggered! shrink_dcache_for_umount [4] [system_dfl_wq] [5] netfs_free_request ... _cifsFileInfo_put // cfile->count 1->0 --cfile->count queue_work(fileinfo_put_wq, xxx)

[fileinfo_put_wq] [6] cifsFileInfo_put_work cifsFileInfo_put_final dput

If the umount path is triggered before [5], it results warning: BUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test} still in use (1) [unmou…

Affected: Ubuntu:26.04:LTS: linux, Ubuntu:26.04:LTS: linux-aws, Ubuntu:26.04:LTS: linux-gcp, Ubuntu:26.04:LTS: linux-gke, Ubuntu:26.04:LTS: linux-ibm, Ubuntu:26.04:LTS: linux-oracle, Ubuntu:26.04:LTS: linux-realtime

It was discovered that some AMD processors did not properly perform Reverse Map Table (RMP) checks when the IOMMU accessed certain host buffers. A local attacker with hypervisor access could possibly use this to trigger an out-of-bounds condition and compromise the integrity of SEV-SNP guest memory. (CVE-2023-20585)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - NVDIMM (Non-Volatile Memory Device) drivers; - Handshake API; - ARM32 architecture; - MIPS architecture; - OpenRISC architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Cryptographic API; - Compute Acceleration Framework; - Intel NPU Driver; - ACPI drivers; - Android drivers; - Serial ATA and Parallel ATA drivers; - Drivers core; - Rados block device (RBD) driver; - Ublk userspace block driver; - Bluetooth drivers; - Cdrom driver; - Character device driver; - TPM device driver; - Data acquisition framework and drivers; - Hardware crypto device drivers; - CXL (Compute Express Link) drivers; - DAX dirext access to differentiated memory framework; - DIBS (Direct Internal Buffer Sharing) drivers; - Buffer Sharing and Synchronization framework; - DMA engine subsystem; - DPLL subsystem; - EDAC drivers; - FireWire subsystem; - Arm Firmware Framework fo…