CVE-2026-80986

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

net/smc: bound the peer rkey counts in SMC-Rv2 LLC messages

On a link whose device has max_recv_sge == 1 there is no shared v2 receive
buffer, and smc_llc_save_add_link_rkeys() takes the v2 extension from 44
bytes past the start of the queue entry's inline message:

  ext = (struct smc_llc_msg_add_link_v2_ext *)(llc_msg + SMC_WR_TX_SIZE);

The entry is a 72-byte allocation and the extension starts at offset 68, so
ext->num_rkeys at offset 94 is already past it. This happens on every
SMC-Rv2 link addition, whatever the peer sends:

  [    2.490065] BUG: KASAN: slab-out-of-bounds in smc_llc_save_add_link_rkeys+0x333/0x350
  [    2.490431] Read of size 2 at addr ffff8880056406de by task smctest/106
  [    2.490709]
  [    2.490792] CPU: 0 UID: 0 PID: 106 Comm: smctest Not tainted 7.2.0-rc5-p1-g77a5d9d9c99f #32 PREEMPT(lazy)
  [    2.490795] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
  [    2.490798] Call Trace:
  [    2.490803]  <TASK>
  [    2.490805]  dump_stack_lvl+0x53/0x70
  [    2.490810]  print_report+0xd0/0x630
  [    2.490828]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
  [    2.490832]  ? smc_llc_save_add_link_rkeys+0x333/0x350
  [    2.490834]  kasan_report+0xce/0x100
  [    2.490836]  ? smc_llc_save_add_link_rkeys+0x333/0x350
  [    2.490837]  smc_llc_save_add_link_rkeys+0x333/0x350
  [    2.490839]  ? smcr_buf_map_lgr+0x1bf/0x2b0
  [    2.490844]  smc_llc_cli_add_link+0xca7/0x1e80
  [    2.490848]  ? smc_llc_wait+0x355/0x810
  [    2.490850]  ? __pfx_smc_llc_wait+0x10/0x10
  [    2.490851]  ? __pfx_smc_llc_cli_add_link+0x10/0x10
  [    2.490853]  ? __pfx_autoremove_wake_function+0x10/0x10
  [    2.490863]  __smc_connect+0x3f5c/0x4980
  [    2.490873]  ? __pfx_kernel_connect+0x10/0x10
  [    2.490888]  ? __pfx___smc_connect+0x10/0x10
  [    2.490891]  ? release_sock+0x148/0x1d0
  [    2.490894]  smc_connect+0x42c/0x580
  [    2.490896]  __sys_connect+0xfc/0x130
  [    2.490898]  ? __pfx___sys_connect+0x10/0x10
  [    2.490900]  ? handle_mm_fault+0x1a1/0x430
  [    2.490908]  __x64_sys_connect+0x6d/0xb0
  [    2.490909]  ? fpregs_assert_state_consistent+0x56/0xe0
  [    2.490917]  do_syscall_64+0xf9/0x540
  [    2.490921]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
  [    2.490924] RIP: 0033:0x421bb4
  [    2.490927] Code: ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 80 3d ad 34 09 00 00 74 13 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 4c c3 0f 1f 00 55 48 89 e5 48 83 ec 10 89 55
  [    2.490929] RSP: 002b:00007ffd473b01a8 EFLAGS: 00000202 ORIG_RAX: 000000000000002a
  [    2.490935] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000421bb4
  [    2.490936] RDX: 0000000000000010 RSI: 00007ffd473b01d0 RDI: 0000000000000003
  [    2.490937] RBP: 0000000000003930 R08: 0000000000000004 R09: 0000000000000000
  [    2.490938] R10: 00007ffd473b0f98 R11: 0000000000000202 R12: 0000000000000006
  [    2.490939] R13: 00007ffd473b0f87 R14: 0000000000000003 R15: 00007ffd473b0f90
  [    2.490940]  </TASK>
  [    2.490941]
  [    2.499545] Allocated by task 44:
  [    2.499693]  kasan_save_stack+0x33/0x60
  [    2.499860]  kasan_save_track+0x14/0x30
  [    2.500026]  __kasan_kmalloc+0x8f/0xa0
  [    2.500190]  __kmalloc_cache_noprof+0x158/0x370
  [    2.500393]  smc_llc_enqueue+0x72/0x560
  [    2.500559]  smc_wr_rx_tasklet_fn+0x474/0xa80
  [    2.500747]  tasklet_action_common+0x20f/0x8a0
  [    2.500945]  handle_softirqs+0x18e/0x590
  [    2.501115]  do_softirq+0x3b/0x60
  [    2.501266]  __local_bh_enable_ip+0x61/0x70
  [    2.501446]  __alloc_skb+0x732/0x890
  [    2.501604]  rxe_init_packet+0x16b/0x4f0
  [    2.501783]  prepare_ack_packet+0xb8/0x830
  [    2.501962]  rxe_receiver+0x495/0x96e0
  [    2.502125]  do_work+0x144/0x470
  [    2.502269]  process_one_work+0x633/0x1030
  [    2.502450]  worker_thread+0x45b/0xd10
  [    2.50261
---truncated---