Vulnerabilidades

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()<br /> <br /> Drop a BUG_ON() that has been reachable since it was first added, way back<br /> in 2009, and instead use get_unaligned() to perform potentially-unaligned<br /> accesses.<br /> <br /> For a given store, KVM x86&amp;#39;s emulator tracks the entire value in the<br /> destination operand, x86_emulate_ctxt.dst. If the destination is memory,<br /> and the target splits multiple pages and/or is emulated MMIO, then KVM<br /> handles each fragment independently. E.g. on a page split starting at page<br /> offset 0xffc, KVM writes 4 bytes to the first page, then the remaining<br /> bytes to the second page, using ctxt-&gt;dst as the source for both (with<br /> appropriate offsets).<br /> <br /> If the destination splits a page *and* hits emulated MMIO on the second<br /> page, then KVM will complete the write to the first page, then emulate the<br /> MMIO access to the second page. If there is a datamatch-enabled ioeventfd<br /> at offset 0 of the second page, then KVM will process the remainder of the<br /> store as a potential ioeventfd signal.<br /> <br /> Putting it all together, if the guest emits a store that splits a page<br /> starting at page offset N, and the second page has a datamatch-enabled<br /> ioeventfd at offset 0, then KVM will check for datamatch using<br /> &amp;dst.valptr[N] as the source. Due to dst (and thus dst.valptr) being<br /> 32-byte aligned, if N is not aligned to @len, the BUG_ON() fires.<br /> <br /> E.g. with a 16-byte store at page offset 0xffc, to an ioeventfd of len 8,<br /> all initial checks in ioeventfd_in_range() will succeed, and the BUG_ON()<br /> fires due to @val being 4-byte aligned, but not 8-byte aligned.<br /> <br /> ------------[ cut here ]------------<br /> kernel BUG at arch/x86/kvm/../../../virt/kvm/eventfd.c:783!<br /> Oops: invalid opcode: 0000 [#1] SMP<br /> CPU: 0 UID: 1000 PID: 615 Comm: repro Not tainted 7.1.0-rc2-ff238429d1ea #365 PREEMPT<br /> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015<br /> RIP: 0010:ioeventfd_write+0x6c/0x70 [kvm]<br /> Call Trace:<br /> <br /> __kvm_io_bus_write+0x85/0xb0 [kvm]<br /> kvm_io_bus_write+0x53/0x80 [kvm]<br /> vcpu_mmio_write+0x66/0xf0 [kvm]<br /> emulator_read_write_onepage+0x12a/0x540 [kvm]<br /> emulator_read_write+0x109/0x2b0 [kvm]<br /> x86_emulate_insn+0x4f8/0xfb0 [kvm]<br /> x86_emulate_instruction+0x181/0x790 [kvm]<br /> kvm_mmu_page_fault+0x313/0x630 [kvm]<br /> vmx_handle_exit+0x18a/0x590 [kvm_intel]<br /> kvm_arch_vcpu_ioctl_run+0xc81/0x1c90 [kvm]<br /> kvm_vcpu_ioctl+0x2d5/0x970 [kvm]<br /> __x64_sys_ioctl+0x8a/0xd0<br /> do_syscall_64+0xb7/0x890<br /> entry_SYSCALL_64_after_hwframe+0x4b/0x53<br /> RIP: 0033:0x7f19c931a9bf<br /> <br /> Modules linked in: kvm_intel kvm irqbypass<br /> ---[ end trace 0000000000000000 ]---<br /> <br /> In a perfect world, the fix would be to simply delete the BUG_ON(), as KVM<br /> x86 doesn&amp;#39;t perform alignment checks on "normal" memory accesses at CPL0.<br /> Sadly, C99 ruins all the fun; while the x86 architecture plays nice,<br /> dereferencing an unaligned pointer directly is undefined behavior in C,<br /> e.g. triggers splats when running with CONFIG_UBSAN_ALIGNMENT=y.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> KVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level<br /> <br /> When recovering hugepages in the shadow MMU, verify that the base gfn of<br /> the shadow page is actually contained within the target memslot, *before*<br /> querying the max mapping level given the shadow page&amp;#39;s gfn. Failure to<br /> pre-check the validity of the gfn can lead to an out-of-bounds access to<br /> the slot&amp;#39;s lpage_info (which typically manifests as a host #PF because the<br /> lpage_info is vmalloc&amp;#39;d) if the guest creates a hugepage mapping (in its<br /> PTEs) that extends "below" the bounds of a memslot.<br /> <br /> When faulting in memory for a guest, and the size of the guest mapping is<br /> greater than KVM&amp;#39;s (current) max mapping, then KVM will create a "direct"<br /> shadow page (direct in that there are no gPTEs to shadow, and so the target<br /> gfn is a direct calculation given the base gfn of the shadow page). The<br /> hugepage recovery flow looks for such direct shadow pages, as forcing 4KiB<br /> mappings when dirty logging generates the guest &gt; host mapping size case.<br /> When the 4KiB restriction is lifted, then KVM can replace the shadow page<br /> with a hugepage.<br /> <br /> But if KVM originally used a smaller mapping than the guest because the<br /> range of memory covered by the guest hugepage exceeds the bounds of a<br /> memslot, then KVM will link a direct shadow page with a gfn that is outside<br /> the bounds of the memslot being used to fault in memory. The rmap entry<br /> added for the leaf mapping is correct and within bounds, but the gfn of the<br /> leaf SPTE&amp;#39;s parent shadow page will be out of bounds.<br /> <br /> BUG: unable to handle page fault for address: ffffc90000806ffc<br /> #PF: supervisor read access in kernel mode<br /> #PF: error_code(0x0000) - not-present page<br /> PGD 100000067 P4D 100000067 PUD 1002a7067 PMD 10612f067 PTE 0<br /> Oops: Oops: 0000 [#1] SMP<br /> CPU: 13 UID: 1000 PID: 757 Comm: mmu_stress_test Not tainted 7.1.0-rc1-48ce1e26eace-x86_pir_to_irr_comments-vm #341 PREEMPT<br /> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015<br /> RIP: 0010:kvm_mmu_max_mapping_level+0x79/0x2b0 [kvm]<br /> Call Trace:<br /> <br /> kvm_mmu_recover_huge_pages+0x21b/0x320 [kvm]<br /> kvm_set_memslot+0x1ee/0x590 [kvm]<br /> kvm_set_memory_region.part.0+0x3a1/0x4d0 [kvm]<br /> kvm_vm_ioctl+0x9bf/0x15d0 [kvm]<br /> __x64_sys_ioctl+0x8a/0xd0<br /> do_syscall_64+0xb7/0xbb0<br /> entry_SYSCALL_64_after_hwframe+0x4b/0x53<br /> RIP: 0033:0x7f21c0f1a9bf<br /> <br /> <br /> Don&amp;#39;t bother pre-checking the bounds of the potential hugepage, i.e. don&amp;#39;t<br /> check that e.g. sp-&gt;gfn + KVM_PAGES_PER_HPAGE(sp-&gt;role.level + 1) is also<br /> within the memslot, as the checks performed by kvm_mmu_max_mapping_level()<br /> are a superset of the basic bounds checks. I.e. pre-checking the full<br /> range would be a dubious micro-optimization.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> exfat: fix potential use-after-free in exfat_find_dir_entry()<br /> <br /> In exfat_find_dir_entry(), the buffer_head obtained from<br /> exfat_get_dentry() is released with brelse(bh) before the fall-through<br /> TYPE_EXTEND branch reads the directory entry through ep (which points<br /> into bh-&gt;b_data):<br /> <br /> brelse(bh);<br /> if (entry_type == TYPE_EXTEND) {<br /> ...<br /> len = exfat_extract_uni_name(ep, entry_uniname);<br /> ...<br /> }<br /> <br /> After brelse() drops our reference, nothing guarantees that the<br /> underlying page backing bh-&gt;b_data remains valid for the subsequent<br /> exfat_extract_uni_name() read. This is the same pattern fixed in<br /> commit fc961522ddbd ("exfat: Fix potential use after free in<br /> exfat_load_upcase_table()").<br /> <br /> Move brelse(bh) so it runs after ep is no longer dereferenced on<br /> each branch.<br /> <br /> Confirmed on QEMU x86_64 with CONFIG_KASAN=y + CONFIG_DEBUG_PAGEALLOC=y<br /> + CONFIG_PAGE_POISONING=y on linux-next, using a crafted exFAT image<br /> (long filename with same-hash collisions forcing the TYPE_EXTEND path).<br /> With a debug-only invalidate_bdev() inserted between brelse(bh) and<br /> the ep read to make the stale-deref window deterministic, the<br /> unpatched kernel faults:<br /> <br /> BUG: KASAN: use-after-free in exfat_find_dir_entry+0x133b/0x15a0<br /> BUG: unable to handle page fault for address: ffff88801a5fa0c2<br /> Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI<br /> RIP: 0010:exfat_find_dir_entry+0x1188/0x15a0<br /> <br /> With this patch applied, the same instrumented harness completes<br /> cleanly under the same sanitizer stack. I have not reproduced a<br /> crash on an uninstrumented kernel under ordinary reclaim; the<br /> instrumented A/B establishes the lifetime violation and that the<br /> patch closes it, not an unaided triggerability claim.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> bpf: use kvfree() for replaced sysctl write buffer<br /> <br /> proc_sys_call_handler() allocates its temporary sysctl buffer with<br /> kvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since<br /> kvzalloc() may fall back to vmalloc() for large allocations, freeing<br /> that buffer with kfree() is wrong and can corrupt memory.<br /> <br /> Use kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc<br /> allocations.<br /> <br /> The bug was first flagged by an experimental analysis tool we are<br /> developing for kernel memory-management bugs while analyzing<br /> v6.13-rc1. The tool is still under development and is not yet publicly<br /> available. Manual inspection confirms that the bug is still<br /> present in v7.1-rc5.<br /> <br /> Reproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with<br /> KASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the<br /> test tree also included the accompanying fix for the stale ret == 1<br /> check in __cgroup_bpf_run_filter_sysctl(). The reproducer confines<br /> failslab injections to the proc_sys_call_handler() range, uses<br /> stacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to<br /> /proc/sys/kernel/domainname from a task in the target cgroup. Under<br /> that setup, fail-nth=1 triggered the fault:<br /> <br /> BUG: unable to handle page fault for address: ffffeb0200024d48<br /> #PF: supervisor read access in kernel mode<br /> #PF: error_code(0x0000) - not-present page<br /> PGD 0 P4D 0<br /> Oops: Oops: 0000 SMP KASAN NOPTI<br /> CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy)<br /> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014<br /> RIP: 0010:kfree+0x6e/0x510<br /> ...<br /> Call Trace:<br /> <br /> ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30<br /> __cgroup_bpf_run_filter_sysctl+0x74d/0xc30<br /> ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10<br /> ? srso_return_thunk+0x5/0x5f<br /> ? __kvmalloc_node_noprof+0x345/0x870<br /> ? proc_sys_call_handler+0x250/0x480<br /> ? srso_return_thunk+0x5/0x5f<br /> proc_sys_call_handler+0x3a2/0x480<br /> ? __pfx_proc_sys_call_handler+0x10/0x10<br /> ? srso_return_thunk+0x5/0x5f<br /> ? selinux_file_permission+0x39f/0x500<br /> ? srso_return_thunk+0x5/0x5f<br /> ? lock_is_held_type+0x9e/0x120<br /> vfs_write+0x98e/0x1000<br /> ...<br /> <br /> <br /> With this fix applied on top of the same test setup, rerunning the<br /> reproducer with fail-nth=1 yields no corresponding Oops reports.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> block: Avoid mounting the bdev pseudo-filesystem in userspace<br /> <br /> The bdev pseudo-filesystem is an internal kernel filesystem with which<br /> userspace should not interfere. Unregister it so that userspace cannot<br /> even attempt to mount it.<br /> <br /> This fixes a bug [1] that occurs when attempting to access files,<br /> because the system call move_mount() uses pointers declared in the<br /> inode_operations structure, which for the bdev pseudo-filesystem<br /> are always equal to 0. `inode-&gt;i_op = &amp;empty_iops;`<br /> <br /> [1]<br /> <br /> BUG: kernel NULL pointer dereference, address: 0000000000000000<br /> #PF: supervisor instruction fetch in kernel mode<br /> #PF: error_code(0x0010) - not-present page<br /> PGD 23380067 P4D 23380067 PUD 23381067 PMD 0<br /> Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI<br /> CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014<br /> RIP: 0010:0x0<br /> <br /> Call Trace:<br /> <br /> lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460<br /> open_last_lookups fs/namei.c:3550 [inline]<br /> path_openat+0x953/0x2700 fs/namei.c:3780<br /> do_filp_open+0x1c5/0x410 fs/namei.c:3810<br /> do_sys_openat2+0x171/0x4d0 fs/open.c:1318<br /> do_sys_open fs/open.c:1334 [inline]<br /> __do_sys_openat fs/open.c:1350 [inline]<br /> __se_sys_openat fs/open.c:1345 [inline]<br /> __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345<br /> do_syscall_x64 arch/x86/entry/common.c:51 [inline]<br /> do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81<br /> entry_SYSCALL_64_after_hwframe+0x6e/0xd8<br /> <br /> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ocfs2: reject oversized group bitmap descriptors<br /> <br /> ocfs2_validate_gd_parent() only bounds bg_bits against the parent<br /> allocator&amp;#39;s chain geometry. A malicious descriptor can still claim a<br /> bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in<br /> the group descriptor block, so later bitmap scans and bit updates can run<br /> past bg_bitmap.<br /> <br /> Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent<br /> allocator type and reject descriptors whose bg_size or bg_bits exceed that<br /> capacity. Keep the existing chain geometry check so both the on-disk<br /> bitmap layout and the allocator metadata must agree before the descriptor<br /> is used.<br /> <br /> Validation reproduced this kernel report:<br /> KASAN use-after-free in _find_next_bit+0x7f/0xc0<br /> Read of size 8<br /> Call trace:<br /> dump_stack_lvl+0x66/0xa0 (?:?)<br /> print_report+0xd0/0x630 (?:?)<br /> _find_next_bit+0x7f/0xc0 (?:?)<br /> srso_alias_return_thunk+0x5/0xfbef5 (?:?)<br /> __virt_addr_valid+0x188/0x2f0 (?:?)<br /> kasan_report+0xe4/0x120 (?:?)<br /> ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)<br /> ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)<br /> ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)<br /> ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)<br /> ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)<br /> get_page_from_freelist+0x70e/0x2370 (?:?)<br /> lock_release+0xc6/0x290 (?:?)<br /> do_raw_spin_unlock+0x9a/0x100 (?:?)<br /> kasan_unpoison+0x27/0x60 (?:?)<br /> __bfs+0x147/0x240 (?:?)<br /> get_page_from_freelist+0x83d/0x2370 (?:?)<br /> ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)<br /> sched_domains_numa_masks_clear+0x70/0xd0 (?:?)<br /> check_irq_usage+0xe8/0xb70 (?:?)<br /> __ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)<br /> check_path+0x24/0x50 (?:?)<br /> rcu_is_watching+0x20/0x50 (?:?)<br /> check_prev_add+0xfd/0xd00 (?:?)<br /> ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)<br /> __folio_batch_add_and_move+0x1f5/0x3d0 (?:?)<br /> ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)<br /> filemap_add_folio+0x105/0x1f0 (?:?)<br /> ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)<br /> ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)<br /> down_write+0xf5/0x180 (?:?)<br /> ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)<br /> __mark_inode_dirty+0x758/0x9a0 (?:?)<br /> inode_to_bdi+0x41/0x90 (?:?)<br /> balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)<br /> generic_perform_write+0x252/0x440 (?:?)<br /> mnt_put_write_access_file+0x16/0x70 (?:?)<br /> file_update_time_flags+0xe4/0x200 (?:?)<br /> ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)<br /> lock_acquire+0x184/0x2f0 (?:?)<br /> ksys_write+0xd2/0x170 (?:?)<br /> apparmor_file_permission+0xf5/0x310 (?:?)<br /> read_zero+0x8d/0x140 (?:?)<br /> lock_is_held_type+0x8f/0x100 (?:?)

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> rpmsg: char: Fix use-after-free on probe error path<br /> <br /> rpmsg_chrdev_probe() stores the newly allocated eptdev in the default<br /> endpoint&amp;#39;s priv pointer before calling rpmsg_chrdev_eptdev_add(). If<br /> rpmsg_chrdev_eptdev_add() then fails, its error path frees eptdev while<br /> the default endpoint may still dispatch callbacks with the stale priv<br /> pointer.<br /> <br /> Avoid publishing eptdev through the default endpoint until<br /> rpmsg_chrdev_eptdev_add() succeeds. Messages received before the priv<br /> pointer is published should be ignored by rpmsg_ept_cb(). Flow-control<br /> updates can hit rpmsg_ept_flow_cb() in the same window, so make both<br /> callbacks return success when priv is NULL.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> irqchip/imgpdc: Fix resource leak, add missing chained handler cleanup on remove<br /> <br /> The driver allocates domain generic chips using<br /> irq_alloc_domain_generic_chips() during probe and sets up chained<br /> handlers using irq_set_chained_handler_and_data(). However, on driver<br /> removal, the generic chips are not freed and the chained handlers are<br /> not removed.<br /> <br /> The generic chips remain on the global gc_list and may later be accessed by<br /> generic interrupt chip suspend, resume, or shutdown callbacks after the<br /> driver has been removed, potentially resulting in a use-after-free and<br /> kernel crash.<br /> <br /> The chained handlers that were installed in probe for peripheral and<br /> syswake interrupts are also left dangling, which can lead to spurious<br /> interrupts accessing freed memory.<br /> <br /> Fix these issues by:<br /> <br /> - Setting IRQ_DOMAIN_FLAG_DESTROY_GC flag in domain-&gt;flags, so the<br /> core code automatically removes generic chips when irq_domain_remove()<br /> is called<br /> <br /> - Clearing all chained handlers with NULL in pdc_intc_remove()

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> sched/mmcid: Fix OOB clear_bit when CID is MM_CID_UNSET in fixup path<br /> <br /> In mm_cid_fixup_cpus_to_tasks(), when rq-&gt;curr has the target mm and<br /> mm_cid.active is set, the CID is checked with cid_in_transit() before<br /> setting the transition bit. In per-CPU mode a newly forked or exec&amp;#39;d<br /> task can be running with mm_cid.cid == MM_CID_UNSET because CIDs are<br /> assigned lazily on schedule-in. With cid_in_transit() the guard passes<br /> for MM_CID_UNSET (no transit bit), converts it to MM_CID_UNSET |<br /> MM_CID_TRANSIT and stores it back; later mm_cid_schedout() feeds this<br /> to clear_bit() with MM_CID_UNSET as the bit number, triggering an<br /> out-of-bounds write.<br /> <br /> Symptoms: this is genuine memory corruption, but a bounded out-of-bounds<br /> write, not an arbitrary one. MM_CID_UNSET is the fixed sentinel BIT(31),<br /> so once the bad value reaches mm_cid_schedout() the cid_from_transit_cid()<br /> strip leaves MM_CID_UNSET, which fails the "cid clear_bit(MM_CID_UNSET,<br /> mm_cidmask(mm)). The cid bitmap is embedded in the mm_struct slab object<br /> (after cpu_bitmap and mm_cpus_allowed) and is only num_possible_cpus()<br /> bits wide, so clearing bit 31 is a deterministic OOB bit-clear at a<br /> fixed offset of 2^31 / 8 == 256 MiB past the bitmap base. The address is<br /> not attacker-influenced (fixed sentinel -&gt; fixed offset) and the op only<br /> clears a single bit; what sits 256 MiB further along the direct map is<br /> whatever kernel object happens to live there, so this corrupts one bit of<br /> unpredictable kernel memory -- it is not an arbitrary-address or<br /> arbitrary-value write.<br /> <br /> It triggers only in per-CPU CID mode, when a CPU is running an active<br /> task of the target mm whose cid is still MM_CID_UNSET -- the<br /> fork()/execve() window before that task&amp;#39;s next schedule-in assigns it a<br /> real CID -- and a per-CPU -&gt; per-task fixup walks over it (the mode<br /> fallback driven by a thread exit, sched_mm_cid_exit(), or by the deferred<br /> max_cids recompute in mm_cid_work_fn()).<br /> <br /> In practice syzkaller surfaced it as a KASAN use-after-free reported in<br /> __schedule -&gt; mm_cid_switch_to, where the offending clear_bit() is inlined<br /> via mm_cid_schedout() -&gt; mm_drop_cid().<br /> <br /> Guard the transition-bit assignment against MM_CID_UNSET, in addition to<br /> the existing cid_in_transit() check, so the bit is only set on a genuine<br /> task-owned CID. A CPU-owned (MM_CID_ONCPU) CID of a running active task<br /> is handled by the cid_on_cpu(pcp-&gt;cid) branch above and never reaches<br /> this path, so excluding MM_CID_UNSET (and the already-transitioning case)<br /> is sufficient.

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> pNFS: Fix use-after-free in pnfs_update_layout()<br /> <br /> When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(),<br /> the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds,<br /> pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(),<br /> which still references &amp;#39;lo&amp;#39;. This results in a use-after-free when the<br /> tracepoint accesses lo&amp;#39;s fields.<br /> <br /> Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo).

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tipc: fix slab-use-after-free Read in tipc_aead_decrypt_done<br /> <br /> tipc_aead_decrypt() goes straight from tipc_bearer_hold(b) to<br /> crypto_aead_decrypt(req) without taking a reference on the netns, unlike<br /> the encrypt path. When crypto_aead_decrypt() is offloaded asynchronously<br /> (e.g. the SIMD aead wrapper queuing to cryptd), the cryptd worker runs<br /> tipc_aead_decrypt_done() later. If the bearer&amp;#39;s netns is torn down in the<br /> meantime, cleanup_net() -&gt; tipc_exit_net() -&gt; tipc_crypto_stop() frees the<br /> per-netns tipc_crypto, and the completion then reads it:<br /> tipc_aead_decrypt_done() dereferences aead-&gt;crypto-&gt;stats and<br /> aead-&gt;crypto-&gt;net, and tipc_crypto_rcv_complete() dereferences<br /> aead-&gt;crypto-&gt;aead[] and the node table -- reading freed memory.<br /> <br /> Decoded KASAN splat (v7.1-rc7, CONFIG_KASAN_INLINE + TIPC + TIPC_CRYPTO):<br /> <br /> BUG: KASAN: slab-use-after-free in tipc_aead_decrypt_done (net/tipc/crypto.c:999)<br /> Read of size 8 at addr ffff8881056258a8 by task kworker/u16:2/51<br /> Workqueue: events_unbound<br /> Call Trace:<br /> tipc_aead_decrypt_done (net/tipc/crypto.c:999)<br /> process_one_work (kernel/workqueue.c:3314)<br /> worker_thread (kernel/workqueue.c:3397 kernel/workqueue.c:3478)<br /> kthread (kernel/kthread.c:436)<br /> ret_from_fork (arch/x86/kernel/process.c:158)<br /> ret_from_fork_asm (arch/x86/entry/entry_64.S:245)<br /> <br /> Allocated by task 169:<br /> __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415)<br /> tipc_crypto_start (net/tipc/crypto.c:1502)<br /> tipc_init_net (net/tipc/core.c:72)<br /> ops_init (net/core/net_namespace.c:137)<br /> setup_net (net/core/net_namespace.c:446)<br /> copy_net_ns (net/core/net_namespace.c:579)<br /> create_new_namespaces (kernel/nsproxy.c:132)<br /> __x64_sys_unshare (kernel/fork.c:3316)<br /> do_syscall_64 (arch/x86/entry/syscall_64.c:63)<br /> entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)<br /> <br /> Freed by task 8:<br /> kfree (mm/slub.c:6566)<br /> tipc_exit_net (net/tipc/core.c:119)<br /> cleanup_net (net/core/net_namespace.c:704)<br /> process_one_work (kernel/workqueue.c:3314)<br /> kthread (kernel/kthread.c:436)<br /> <br /> This is the same class of bug that commit e279024617134 ("net/tipc: fix<br /> slab-use-after-free Read in tipc_aead_encrypt_done") fixed for the encrypt<br /> side. The encrypt path takes maybe_get_net(aead-&gt;crypto-&gt;net) before<br /> crypto_aead_encrypt() and drops it with put_net() on the synchronous<br /> return paths and in tipc_aead_encrypt_done(); the -EINPROGRESS/-EBUSY<br /> return keeps the reference for the async callback to release. The decrypt<br /> path was left without the equivalent guard.<br /> <br /> Mirror the encrypt-side fix on the decrypt path: take a net reference<br /> before crypto_aead_decrypt() (failing with -ENODEV and the matching<br /> bearer put if it cannot be acquired), keep it across the<br /> -EINPROGRESS/-EBUSY async return, and drop it with put_net() on the<br /> synchronous success/error return and at the end of<br /> tipc_aead_decrypt_done().<br /> <br /> Reproduced under KASAN on v7.1-rc7: a UDP bearer with a cluster key is<br /> flooded with crafted encrypted frames from an unknown peer (driving the<br /> cluster-key decrypt path) while the bearer&amp;#39;s netns is repeatedly torn<br /> down. The completion must run asynchronously to outlive<br /> tipc_crypto_stop(); on x86 the stock aesni gcm(aes) now decrypts<br /> synchronously, so the async path was exercised via cryptd offload. The<br /> unguarded aead-&gt;crypto dereference in tipc_aead_decrypt_done() is the<br /> unpatched upstream path; tipc_aead_decrypt() still lacks<br /> maybe_get_net(aead-&gt;crypto-&gt;net), so the completion can outlive the free<br /> on any config where crypto_aead_decrypt() goes async.<br /> <br /> Found by 0sec automated security-research tooling (https://0sec.ai).

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> blk-cgroup: fix UAF in __blkcg_rstat_flush()<br /> <br /> When multiple blkgs in the same blkcg are released concurrently,<br /> a use-after-free can occur. The race happens when one blkg&amp;#39;s<br /> __blkcg_rstat_flush() removes another blkg&amp;#39;s iostat entries via<br /> llist_del_all(). The second blkg sees an empty list and proceeds<br /> to free itself while the first is still iterating over its entries.<br /> <br /> Move the flush from __blkg_release() (RCU callback) to blkg_release()<br /> (before call_rcu). This ensures the RCU grace period waits for any<br /> concurrent flush&amp;#39;s rcu_read_lock() section to complete before freeing.