Linux: >> Linux Kernel >> 6.12.94 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE
FSCTL_SET_SPARSE in fsctl_set_sparse() modifies the file's sparse
attribute and saves it through xattr without any permission checks.
This exposes two issues:
1) A client on a read-only share can change the sparse attribute
on files it opened, even though the share is read-only.
Other FSCTL write operations already check
test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE),
but FSCTL_SET_SPARSE does not.
2) Even on writable shares, clients without FILE_WRITE_DATA or
FILE_WRITE_ATTRIBUTES access should not modify the sparse
attribute. Similar handle-level checks exist in other functions
but are missing here.
Add both share-level writable check and per-handle access check.
Use goto out on error to avoid leaking file references.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
tap: fix stack info leak in tap_ioctl() SIOCGIFHWADDR
In the SIOCGIFHWADDR path, tap_ioctl() copies 16 bytes of an
uninitialised on-stack struct sockaddr_storage to userspace via
ifr_hwaddr, but netif_get_mac_address() only writes sa_family and
dev->addr_len (6 for Ethernet) bytes, leaving sa_data[6..13] uninitialised.
Those 8 trailing bytes leak kernel stack contents; SIOCGIFHWADDR on a
macvtap chardev returns kernel .text and direct-map pointers, defeating
KASLR.
Initialise ss at declaration.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
ip6_vti: set netns_immutable on the fallback device.
john1988 and Noam Rathaus reported that vti6_init_net() does not set the
netns_immutable flag on the per-netns fallback tunnel device (ip6_vti0).
Other similar tunnel drivers (like ip6_tunnel, sit, ip6_gre, and ip_tunnel)
correctly set this flag during their fallback device initialization to
prevent them from being moved to another network namespace.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-19
In the Linux kernel, the following vulnerability has been resolved:
RDMA/rxe: Fix iova-to-va conversion for MR page sizes != PAGE_SIZE
The current implementation incorrectly handles memory regions (MRs) with
page sizes different from the system PAGE_SIZE. The core issue is that
rxe_set_page() is called with mr->page_size step increments, but the
page_list stores individual struct page pointers, each representing
PAGE_SIZE of memory.
ib_sg_to_page() has ensured that when i>=1 either
a) SG[i-1].dma_end and SG[i].dma_addr are contiguous
or
b) SG[i-1].dma_end and SG[i].dma_addr are mr->page_size aligned.
This leads to incorrect iova-to-va conversion in scenarios:
1) page_size < PAGE_SIZE (e.g., MR: 4K, system: 64K):
ibmr->iova = 0x181800
sg[0]: dma_addr=0x181800, len=0x800
sg[1]: dma_addr=0x173000, len=0x1000
Access iova = 0x181800 + 0x810 = 0x182010
Expected VA: 0x173010 (second SG, offset 0x10)
Before fix:
- index = (0x182010 >> 12) - (0x181800 >> 12) = 1
- page_offset = 0x182010 & 0xFFF = 0x10
- xarray[1] stores system page base 0x170000
- Resulting VA: 0x170000 + 0x10 = 0x170010 (wrong)
2) page_size > PAGE_SIZE (e.g., MR: 64K, system: 4K):
ibmr->iova = 0x18f800
sg[0]: dma_addr=0x18f800, len=0x800
sg[1]: dma_addr=0x170000, len=0x1000
Access iova = 0x18f800 + 0x810 = 0x190010
Expected VA: 0x170010 (second SG, offset 0x10)
Before fix:
- index = (0x190010 >> 16) - (0x18f800 >> 16) = 1
- page_offset = 0x190010 & 0xFFFF = 0x10
- xarray[1] stores system page for dma_addr 0x170000
- Resulting VA: system page of 0x170000 + 0x10 = 0x170010 (wrong)
Yi Zhang reported a kernel panic[1] years ago related to this defect.
Solution:
1. Replace xarray with pre-allocated rxe_mr_page array for sequential
indexing (all MR page indices are contiguous)
2. Each rxe_mr_page stores both struct page* and offset within the
system page
3. Handle MR page_size != PAGE_SIZE relationships:
- page_size > PAGE_SIZE: Split MR pages into multiple system pages
- page_size <= PAGE_SIZE: Store offset within system page
4. Add boundary checks and compatibility validation
This ensures correct iova-to-va conversion regardless of MR page size
and system PAGE_SIZE relationship, while improving performance through
array-based sequential access.
Tests on 4K and 64K PAGE_SIZE hosts:
- rdma-core/pytests
$ ./build/bin/run_tests.py --dev eth0_rxe
- blktest:
$ TIMEOUT=30 QUICK_RUN=1 USE_RXE=1 NVMET_TRTYPES=rdma ./check nvme srp rnbd
[1] https://lore.kernel.org/all/CAHj4cs9XRqE25jyVw9rj9YugffLn5+f=1znaBEnu1usLOciD+g@mail.gmail.com/T/
CVSS Score
9.8
EPSS Score
0.003
Published
2026-06-09
In the Linux kernel, the following vulnerability has been resolved:
Revert "net/smc: Introduce TCP ULP support"
This reverts commit d7cd421da9da2cc7b4d25b8537f66db5c8331c40.
As reported by Al Viro, the TCP ULP support for SMC is fundamentally
broken. The implementation attempts to convert an active TCP socket
into an SMC socket by modifying the underlying `struct file`, dentry,
and inode in-place, which violates core VFS invariants that assume
these structures are immutable for an open file, creating a risk of
use after free errors and general system instability.
Given the severity of this design flaw and the fact that cleaner
alternatives (e.g., LD_PRELOAD, BPF) exist for legacy application
transparency, the correct course of action is to remove this feature
entirely.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-09
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Reassign nested_mmus array behind mmu_lock
kvm->arch.nested_mmus[] is walked under kvm->mmu_lock, including from the
MMU notifier path (kvm_unmap_gfn_range() -> kvm_nested_s2_unmap()), which
can run at any time. kvm_vcpu_init_nested() reallocates the array and frees
the old buffer while holding only kvm->arch.config_lock, so such a walker
can reference the freed array.
Allocate the new array outside of mmu_lock, as the allocation can sleep.
Under the lock, copy the existing entries, fix up the back pointers and
reassign the array. Free the old buffer after dropping the lock, as
kvfree() can sleep as well.
CVSS Score
8.8
EPSS Score
0.001
Published
2026-06-09
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: use list_del_rcu for netlink hooks
nft_netdev_unregister_hooks and __nft_unregister_flowtable_net_hooks need
to use list_del_rcu(), this list can be walked by concurrent dumpers.
Add a new helper and use it consistently.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-09
In the Linux kernel, the following vulnerability has been resolved:
drm/v3d: Reject empty multisync extension to prevent infinite loop
v3d_get_extensions() walks a userspace-provided singly-linked list of
ioctl extensions without any bound on the chain length. A local user
can craft a self-referential extension (ext->next == &ext) with zero
in_sync_count and out_sync_count, which bypasses the existing duplicate-
extension guard:
if (se->in_sync_count || se->out_sync_count)
return -EINVAL;
The guard never fires because v3d_get_multisync_post_deps() returns
immediately when count is zero, leaving both fields at zero on every
iteration. The result is an infinite loop in kernel context, blocking
the calling thread and pegging a CPU core indefinitely.
Fix this by rejecting a multisync extension where both in_sync_count
and out_sync_count are zero in v3d_get_multisync_submit_deps(). An
empty multisync carries no synchronization information and serves no
useful purpose, so returning -EINVAL for such an extension is the
correct defense against this attack vector.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-08
In the Linux kernel, the following vulnerability has been resolved:
selinux: allow multiple opens of /sys/fs/selinux/policy
Currently there can only be a single open of /sys/fs/selinux/policy at
any time. This allows any process to block any other process from
reading the kernel policy. The original motivation seems to have been
a mix of preventing an inconsistent view of the policy size and
preventing userspace from allocating kernel memory without bound, but
this is arguably equally bad. Eliminate the policy_opened flag and
shrink the critical section that the policy mutex is held. While we
are making changes here, drop a couple of extraneous BUG_ONs.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-06-08
In the Linux kernel, the following vulnerability has been resolved:
mm/alloc_tag: clear codetag for pages allocated before page_ext initialization
Due to initialization ordering, page_ext is allocated and initialized
relatively late during boot. Some pages have already been allocated and
freed before page_ext becomes available, leaving their codetag
uninitialized.
A clear example is in init_section_page_ext(): alloc_page_ext() calls
kmemleak_alloc(). If the slab cache has no free objects, it falls back to
the buddy allocator to allocate memory. However, at this point page_ext
is not yet fully initialized, so these newly allocated pages have no
codetag set. These pages may later be reclaimed by KASAN, which causes
the warning to trigger when they are freed because their codetag ref is
still empty.
Use a global array to track pages allocated before page_ext is fully
initialized. The array size is fixed at 8192 entries, and will emit a
warning if this limit is exceeded. When page_ext initialization
completes, set their codetag to empty to avoid warnings when they are
freed later.
This warning is only observed with CONFIG_MEM_ALLOC_PROFILING_DEBUG=Y and
mem_profiling_compressed disabled:
[ 9.582133] ------------[ cut here ]------------
[ 9.582137] alloc_tag was not set
[ 9.582139] WARNING: ./include/linux/alloc_tag.h:164 at __pgalloc_tag_sub+0x40f/0x550, CPU#5: systemd/1
[ 9.582190] CPU: 5 UID: 0 PID: 1 Comm: systemd Not tainted 7.0.0-rc4 #1 PREEMPT(lazy)
[ 9.582192] Hardware name: Red Hat KVM, BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 9.582194] RIP: 0010:__pgalloc_tag_sub+0x40f/0x550
[ 9.582196] Code: 00 00 4c 29 e5 48 8b 05 1f 88 56 05 48 8d 4c ad 00 48 8d 2c c8 e9 87 fd ff ff 0f 0b 0f 0b e9 f3 fe ff ff 48 8d 3d 61 2f ed 03 <67> 48 0f b9 3a e9 b3 fd ff ff 0f 0b eb e4 e8 5e cd 14 02 4c 89 c7
[ 9.582197] RSP: 0018:ffffc9000001f940 EFLAGS: 00010246
[ 9.582200] RAX: dffffc0000000000 RBX: 1ffff92000003f2b RCX: 1ffff110200d806c
[ 9.582201] RDX: ffff8881006c0360 RSI: 0000000000000004 RDI: ffffffff9bc7b460
[ 9.582202] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff3a62324
[ 9.582203] R10: ffffffff9d311923 R11: 0000000000000000 R12: ffffea0004001b00
[ 9.582204] R13: 0000000000002000 R14: ffffea0000000000 R15: ffff8881006c0360
[ 9.582206] FS: 00007ffbbcf2d940(0000) GS:ffff888450479000(0000) knlGS:0000000000000000
[ 9.582208] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9.582210] CR2: 000055ee3aa260d0 CR3: 0000000148b67005 CR4: 0000000000770ef0
[ 9.582211] PKRU: 55555554
[ 9.582212] Call Trace:
[ 9.582213] <TASK>
[ 9.582214] ? __pfx___pgalloc_tag_sub+0x10/0x10
[ 9.582216] ? check_bytes_and_report+0x68/0x140
[ 9.582219] __free_frozen_pages+0x2e4/0x1150
[ 9.582221] ? __free_slab+0xc2/0x2b0
[ 9.582224] qlist_free_all+0x4c/0xf0
[ 9.582227] kasan_quarantine_reduce+0x15d/0x180
[ 9.582229] __kasan_slab_alloc+0x69/0x90
[ 9.582232] kmem_cache_alloc_noprof+0x14a/0x500
[ 9.582234] do_getname+0x96/0x310
[ 9.582237] do_readlinkat+0x91/0x2f0
[ 9.582239] ? __pfx_do_readlinkat+0x10/0x10
[ 9.582240] ? get_random_bytes_user+0x1df/0x2c0
[ 9.582244] __x64_sys_readlinkat+0x96/0x100
[ 9.582246] do_syscall_64+0xce/0x650
[ 9.582250] ? __x64_sys_getrandom+0x13a/0x1e0
[ 9.582252] ? __pfx___x64_sys_getrandom+0x10/0x10
[ 9.582254] ? do_syscall_64+0x114/0x650
[ 9.582255] ? ksys_read+0xfc/0x1d0
[ 9.582258] ? __pfx_ksys_read+0x10/0x10
[ 9.582260] ? do_syscall_64+0x114/0x650
[ 9.582262] ? do_syscall_64+0x114/0x650
[ 9.582264] ? __pfx_fput_close_sync+0x10/0x10
[ 9.582266] ? file_close_fd_locked+0x178/0x2a0
[ 9.582268] ? __x64_sys_faccessat2+0x96/0x100
[ 9.582269] ? __x64_sys_close+0x7d/0xd0
[ 9.582271] ? do_syscall_64+0x114/0x650
[ 9.582273] ? do_syscall_64+0x114/0x650
[ 9.582275] ? clear_bhb_loop+0x50/0xa0
[ 9.582277] ? clear_bhb_l
---truncated---
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-08