CVE-2026-93100

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

fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()

A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put().

The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure.

The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.

These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure.

The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check.

Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrement-to-zero takes rdtgroup_mutex before the count becomes globally visible. The inspection of rdtgroup::flags then runs under the same mutex held by the bulk freers, making the two paths mutually exclusive.

The common case where the count does not reach zero remains lock-free. Defer kernfs_unbreak_active_protection() until after the mutex is dropped since kernfs active protections functionally wrap rdtgroup_mutex. Remove resource group, which in turn drops its kernfs reference, after kernfs protection is restored.

[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]

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

fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()

A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put().

The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure.

The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.

These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure.

The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check.

Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrement-to-zero takes rdtgroup_mutex before the count becomes globally visible. The inspection of rdtgroup::flags then runs under the same mutex held by the bulk freers, making the two paths mutually exclusive.

The common case where the count does not reach zero remains lock-free. Defer kernfs_unbreak_active_protection() until after the mutex is dropped since kernfs active protections functionally wrap rdtgroup_mutex. Remove resource group, which in turn drops its kernfs reference, after kernfs protection is restored.

[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]

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

fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()

A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put().

The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure.

The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.

These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure.

The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check.

Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrement-to-zero takes rdtgroup_mutex before the count becomes globally visible. The inspection of rdtgroup::flags then runs under the same mutex held by the bulk freers, making the two paths mutually exclusive.

The common case where the count does not reach zero remains lock-free. Defer kernfs_unbreak_active_protection() until after the mutex is dropped since kernfs active protections functionally wrap rdtgroup_mutex. Remove resource group, which in turn drops its kernfs reference, after kernfs protection is restored.

[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]

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

fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()

A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put().

The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure.

The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.

These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure.

The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check.

Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrement-to-zero takes rdtgroup_mutex before the count becomes globally visible. The inspection of rdtgroup::flags then runs under the same mutex held by the bulk freers, making the two paths mutually exclusive.

The common case where the count does not reach zero remains lock-free. Defer kernfs_unbreak_active_protection() until after the mutex is dropped since kernfs active protections functionally wrap rdtgroup_mutex. Remove resource group, which in turn drops its kernfs reference, after kernfs protection is restored.

[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]

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

fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()

A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that need the structure to remain valid across a sleep (while waiting on acquiring rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with rdtgroup_kn_put().

The release path is intended to serve as the fallback freer: if the count drops to zero and the group has already been marked RDT_DELETED, rdtgroup_kn_put() frees the structure.

The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting from a resctrl directory remove or resctrl fs unmount act as the primary freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.

These two freers race. rdtgroup_kn_put() commits waitcount == 0 with atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags. Between those two operations a concurrent caller of free_all_child_rdtgrp() or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via atomic_read(), call rdtgroup_remove(), and kfree() the structure.

The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then a use-after-free, and the structure may even be freed twice if the freed memory happens to satisfy the RDT_DELETED flag check.

Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so that the decrement-to-zero takes rdtgroup_mutex before the count becomes globally visible. The inspection of rdtgroup::flags then runs under the same mutex held by the bulk freers, making the two paths mutually exclusive.

The common case where the count does not reach zero remains lock-free. Defer kernfs_unbreak_active_protection() until after the mutex is dropped since kernfs active protections functionally wrap rdtgroup_mutex. Remove resource group, which in turn drops its kernfs reference, after kernfs protection is restored.

[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]

• ipv4: validate checksum_start before completing checksum {CVE-2026-99999}
• slip: remove slip_hangup() to fix use-after-free in slip_receive_buf() {CVE-2026-90057}
• mm/hugetlb: fix list corruption in allocate_file_region_entries() {CVE-2026-74518}
• mm/page_reporting: use system_freezable_wq to fix UAF during suspend {CVE-2026-74481}
• bpf: Fix UAF in sock clone early bailouts {CVE-2026-68399}
• xen/netfront: drop RX packets with a short Ethernet header {CVE-2026-98375}
• net/sched: fix packet loop on netem when duplicate is on {CVE-2026-63983}
• net: Introduce skb tc depth field to track packet loops {CVE-2026-63983}
• ALSA: seq: midi: Serialize output teardown with event_input {CVE-2026-74387}
• netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst {CVE-2026-72255}
• net: thunderbolt: Fix frags[] overflow by bounding frame_count {CVE-2026-72157}
• SUNRPC: svcauth_gss: enforce krb5 token minimum length {CVE-2026-89550}
• rxrpc: serialize kernel accept preallocation with socket teardown {CVE-2026-74436}
• isofs: fix out-of-bounds page array access on empty zisofs block {CVE-2026-89778}
• ata: libata-core: Reject an invalid concurrent positioning ranges count {CVE-2026-72030}
• wifi: mac80211: validate extension-frame layout before RX {CVE-2026-68470}
• wifi: mac80211: pass 'sta' to ieee80211_rx_data_set_sta() {CVE-2026-68470}
• drm/amd/pm: fix pptable use-after-free {CVE-2026-74450}
• smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 {CVE-2026-89637}
• smb: client: clear ce->tgthint in free_tgts() {CVE-2026-89636}
• smb: client: harden DFS cache against invalid target hints {CVE-2026-93210}
• smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() {CVE-2026-89633}
• nouveau/gem: reserve the bo in the info ioctl around the vma lookup {CVE-2026-89553}
• HID: sony: clean up device list on probe failure {CVE-2026-90041}
• drm/amd/display: Fix dangling pointer in CRTC reset function {CVE-2026-93175}
• hwrng: core - fix rng list on registration error {CVE-2026-93163}
• RDMA/rvt: Return NULL after port allocation failure {CVE-2026-93104}
• fs/resctrl: Prevent use-after-free in rdtgroup_kn_put() {CVE-2026-93100}
• bpf: Fix potential UAF when reading bpf link info {CVE-2026-90392}
• HID: synchronize input before cleaning up a failed probe {CVE-2026-90329}
• bpf: Don't predict JMP32 pointer vs zero comparisons {CVE-2026-98041}
• smb: client: cancel reconnect work in clean_demultiplex_info() {CVE-2026-98175}
• smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs {CVE-2026-98171}
• netfilter: cttimeout: prevent UAF during module unload {CVE-2026-97609}
• thunderbolt: Prevent XDomain delayed work use-after-free on disconnect {CVE-2026-74575}
• NFSv4.2: fix LAYOUTSTATS send buffer exhaustion {CVE-2026-90103}
• Squashfs: check block offset is not negative {CVE-2026-90203}
• RDMA/siw: Fix endpoint/socket association handling {CVE-2026-74345}
• HID: hidpp: fix potential UAF in hidpp_connect_event() {CVE-2026-93826}
• hid: hid-logitech-hidpp: avoid unnecessary assignments in hidpp_connect_event {CVE-2026-93826}
• configfs: unhash the dentry before dropping the item in rmdir {CVE-2026-97949}
• ALSA: us122l: Prevent write upgrades for read mappings {CVE-2026-97931}
• smb: client: reject userspace cifs.idmap descriptions {CVE-2026-97564}
• scsi: qla2xxx: Fix use-after-free of qpair work on queue teardown {CVE-2026-97536}
• RDMA/siw: Clear association under lock if siw_qp_modify fails in siw_accept {CVE-2026-98367}
• ALSA: 6fire: fix OOB write from device-reported iso length {CVE-2026-98312}
• scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf {CVE-2026-63887}
• scsi: target: Fix hexadecimal CHAP_I handling {CVE-2026-63886}
• scsi: target: iscsi: Validate CHAP_R length before base64 decode {CVE-2026-63886}
• wifi: mt76: mt76x02: do not WARN on invalid rx descriptor length {CVE-2026-90382}
• nfsd: RCU-protect cl_cb_session to fix…