CVE-2026-64582

Status: UPDATED  |  Advisory ID: CVE-2026-64582

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

RDMA/rxe: Fix a use-after-free problem in rxe_mmap

rxe_mmap() removes a rxe_mmap_info struct from the pending_mmaps list

and releases pending_lock while the struct's kref is still at 1:

list_del_init(&ip->pending_mmaps);

spin_unlock_bh(&rxe->pending_lock); /* ref == 1, no lock held */

ret = remap_vmalloc_range(vma, ip->obj, 0); /* walks PTEs */

[...]

rxe_vma_open(vma); /* kref_get, ref → 2 */

remap_vmalloc_range_partial() walks PTEs without any lock.

A concurrent DESTROY_CQ ioctl on another CPU calls:

kref_put(&q->ip->ref, rxe_mmap_release) /* ref 1→0 */

vfree(ip->obj) /* clears vmalloc PTEs mid-walk */

kfree(ip) /* frees rxe_mmap_info */

This yields:

1. Kernel crash, vmalloc_to_page() returns NULL when vfree wins the

per-PTE race -> vm_insert_page(NULL) → GPF in validate_page_before_insert

2. Page UAF, vmalloc_to_page() reads a stale PTE before vfree clears

it. User VMA holds a PTE to a free'd page which might eventually get

reallocated later by vmalloc which allows the attacker to get a clean

page-level UAF.

It is worth noting that even though a page-level UAF is possible given

the strong primitive, it is statistically very difficult to achieve

given the very short time window (after the last insert_page and before

the kref_get).

The call trace are as below:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI

KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]

CPU: 0 UID: 1000 PID: 413 Comm: poc Not tainted 7.0.0-rc5-dirty #28 PREEMPT(lazy)

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014

RIP: 0010:validate_page_before_insert+0x32/0x300

Code: e5 41 57 41 56 49 89 fe 41 55 41 54 53 48 89 f3 e8 93 b5 a3 ff 48 8d 7b 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 7b 02 00 00 4c 8b 63 08 31 ff 4d 89 e5 41 83 e5

RSP: 0018:ffff88811b15f2f0 EFLAGS: 00000202

RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000

RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000008

RBP: ffff88811b15f318 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881181eee00

R13: 0000000000000000 R14: ffff8881181eee00 R15: ffff8881181eee20

FS: 00007b1e000f76c0(0000) GS:ffff8884268e0000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007b1e00a24ac0 CR3: 0000000116eb3000 CR4: 00000000000006f0

Call Trace:

<TASK>

insert_page+0x8f/0x190

? __pfx_insert_page+0x10/0x10

? kasan_save_alloc_info+0x38/0x60

vm_insert_page+0x2e7/0x400

remap_vmalloc_range_partial+0x212/0x3e0

remap_vmalloc_range+0x6e/0xb0

? __kasan_check_write+0x14/0x30

rxe_mmap+0x2e9/0x5d0

ib_uverbs_mmap+0x1ad/0x2c0

__mmap_region+0x12c2/0x2ad0

? __pfx___mmap_region+0x10/0x10

? __sanitizer_cov_trace_switch+0x58/0xb0

? mas_prev_slot+0x360/0x39c0

? __sanitizer_cov_trace_switch+0x58/0xb0

? mas_next_slot+0x1e5b/0x2f40

? __sanitizer_cov_trace_cmp8+0x18/0x30

? unmapped_area_topdown+0x4dd/0x610

? kfree+0x1b1/0x440

? free_cpumask_var+0x16/0x30

? __kasan_slab_free+0x7d/0xa0

? __sanitizer_cov_trace_cmp8+0x18/0x30

mmap_region+0x2e6/0x3c0

do_mmap+0xa3e/0x12a0

? __pfx_do_mmap+0x10/0x10

? __kasan_check_write+0x14/0x30

? down_write_killable+0xba/0x160

? __pfx_down_write_killable+0x10/0x10

? __sanitizer_cov_trace_cmp4+0x16/0x30

vm_mmap_pgoff+0x2d4/0x4a0

? __pfx_vm_mmap_pgoff+0x10/0x10

? fget+0x1bf/0x270

ksys_mmap_pgoff+0x40c/0x690

? __sanitizer_cov_trace_const_cmp4+0x16/0x30

? __pfx_ksys_mmap_pgoff+0x10/0x10

? __kasan_check_write+0x14/0x30

? _raw_spin_trylock+0xbb/0x130

? __pfx__raw_spin_trylock+0x10/0x10

__x64_sys_mmap+0x135/0x1e0

x64_sys_c

---truncated--- (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References