CVE-2021-47481

What it is

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Initialize the ODP xarray when creating an ODP MR Normally the zero fill would hide the missing initialization, but an errant set to desc_size in reg_create() causes a crash: BUG: unable to handle page fault for address: 0000000800000000 PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 890 Comm: ib_write_bw Not tainted 5.15.0-rc4+ #47 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5_ib_dereg_mr+0x14/0x3b0 [mlx5_ib] Code: 48 63 cd 4c 89 f7 48 89 0c 24 e8 37 30 03 e1 48 8b 0c 24 eb a0 90 0f 1f 44 00 00 41 56 41 55 41 54 55 53 48 89 fb 48 83 ec 30 <48> 8b 2f 65 48 8b 04 25 28 00 00 00 48 89 44 24 28 31 c0 8b 87 c8 RSP: 0018:ffff88811afa3a60 EFLAGS: 00010286 RAX: 000000000000001c RBX: 0000000800000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000800000000 RBP: 0000000800000000 R08: 0000000000000000 R09: c0000000fffff7ff R10: ffff88811afa38f8 R11: ffff88811afa38f0 R12: ffffffffa02c7ac0 R13: 0000000000000000 R14: ffff88811afa3cd8 R15: ffff88810772fa00 FS: 00007f47b9080740(0000) GS:ffff88852cd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000800000000 CR3: 000000010761e003 CR4: 0000000000370ea0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mlx5_ib_free_odp_mr+0x95/0xc0 [mlx5_ib] mlx5_ib_dereg_mr+0x128/0x3b0 [mlx5_ib] ib_dereg_mr_user+0x45/0xb0 [ib_core] ? xas_load+0x8/0x80 destroy_hw_idr_uobject+0x1a/0x50 [ib_uverbs] uverbs_destroy_uobject+0x2f/0x150 [ib_uverbs] uobj_destroy+0x3c/0x70 [ib_uverbs] ib_uverbs_cmd_verbs+0x467/0xb00 [ib_uverbs] ? uverbs_finalize_object+0x60/0x60 [ib_uverbs] ? ttwu_queue_wakelist+0xa9/0xe0 ? pty_write+0x85/0x90 ? file_tty_write.isra.33+0x214/0x330 ? process_echoes+0x60/0x60 ib_uverbs_ioctl+0xa7/0x110 [ib_uverbs] __x64_sys_ioctl+0x10d/0x8e0 ? vfs_write+0x17f/0x260 do_syscall_64+0x3c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Add the missing xarray initialization and remove the desc_size set.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2024-05-22 09:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 5.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2024-05-22 09:15 UTC

Last modified

2026-06-17 04:17 UTC

Exploit probability

0.2% · EPSS, next 30 days

Record status

Analyzed

Affected

• Linux Kernel < 5.13
• Linux Kernel < 5.14.16
• Linux Kernel 5.15

Attack profile CVSS 3.1 · 5.5

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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