CVE-2026-89483

Status: UPDATED  |  Advisory ID: CVE-2026-89483

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

nvme: zero the discard fallback page

nvme_setup_discard() always maps sizeof(struct nvme_dsm_range) *

NVME_DSM_MAX_RANGES = 4096 bytes as the DSM payload however many ranges

the command declares, because some devices ignore the 'Number of Ranges'

field - the Fixes: commit records two that read past the declared ranges.

A single-range discard fills only the first 16 bytes.

Normally the buffer comes from kzalloc() and the other 4080 bytes are

zero. When that allocation fails the code falls back to the

per-controller ctrl->discard_page, which nvme_init_ctrl() obtains with

alloc_page(GFP_KERNEL) and nothing ever zeroes, so those 4080 bytes are

whatever the page last held and are handed to the controller. Reaching

it requires the kzalloc(GFP_ATOMIC | __GFP_NOWARN) to fail, that is

memory pressure; it is not remotely triggerable. Failing the allocation

under KMSAN reproduces it, with the leaked tail full of vmemmap struct

page pointers. The extent in the report is a partial transfer of the

payload, not the whole 4096 bytes; the 16-byte boundary in it is the one

declared range:

[ 11.991601] BUG: KMSAN: uninit-value in dma_map_phys+0x14c8/0x1900

[ 11.991969] dma_map_phys+0x14c8/0x1900

[ 11.992220] dma_map_page_attrs+0xcf/0x130

[ 11.992485] e1000_xmit_frame+0x4099/0x6d10

[ 11.992768] dev_hard_start_xmit+0x22f/0xa80

[ 11.993068] sch_direct_xmit+0x35c/0xcb0

[ 11.993315] __dev_queue_xmit+0x1ee5/0x5eb0

[ 11.993608] ip_finish_output2+0x1903/0x1c30

[ 11.993881] ip_finish_output+0x288/0x870

[ 11.994125] ip_output+0x15e/0x400

[ 11.994365] __ip_queue_xmit+0x1e85/0x1fb0

[ 11.994639] ip_queue_xmit+0x60/0x80

[ 11.994899] __tcp_transmit_skb+0x4e71/0x5fa0

[ 11.995210] tcp_write_xmit+0x3a36/0x9160

[ 11.995533] __tcp_push_pending_frames+0xc5/0x3c0

[ 11.995854] tcp_push+0x7dc/0x840

[ 11.996076] tcp_sendmsg_locked+0x766c/0x8400

[ 11.996371] tcp_sendmsg+0x4b/0x90

[ 11.996572] inet_sendmsg+0x134/0x2a0

[ 11.996823] __sock_sendmsg+0x265/0x360

[ 11.997076] sock_sendmsg+0x100/0x1e0

[ 11.997293] nvme_tcp_try_send+0x196f/0x6370

[ 11.997605] nvme_tcp_queue_rq+0x1d54/0x20b0

[ 11.997882] blk_mq_dispatch_rq_list+0x5ee/0x2e50

[ 11.998175] __blk_mq_sched_dispatch_requests+0x16dc/0x24a0

[ 11.998539] blk_mq_sched_dispatch_requests+0x11b/0x2c0

[ 11.998865] blk_mq_run_work_fn+0x13b/0x280

[ 11.999146] process_scheduled_works+0x966/0x1ad0

[ 11.999465] worker_thread+0xe44/0x1480

[ 11.999709] kthread+0x53b/0x600

[ 11.999927] ret_from_fork+0x29f/0x7c0

[ 12.000191] ret_from_fork_asm+0x1a/0x30

[ 12.000460]

[ 12.000558] Uninit was created at:

[ 12.000788] __alloc_frozen_pages_noprof+0x8bf/0xd30

[ 12.001096] alloc_pages_mpol+0x1d0/0x5f0

[ 12.001326] alloc_pages_noprof+0x102/0x290

[ 12.001627] nvme_init_ctrl+0x5a3/0x9f0

[ 12.001891] nvme_tcp_create_ctrl+0xd75/0x19b0

[ 12.002170] nvmf_dev_write+0x4c68/0x4fd0

[ 12.002426] vfs_write+0x587/0x1a10

[ 12.002636] __x64_sys_write+0x207/0x4f0

[ 12.002874] x64_sys_call+0x2ff0/0x3ea0

[ 12.003123] do_syscall_64+0x147/0x3b0

[ 12.003400] entry_SYSCALL_64_after_hwframe+0x77/0x7f

[ 12.003680]

[ 12.003777] Bytes 16-2843 of 2844 are uninitialized

[ 12.004068] Memory access of size 2844 starts at ffff888109f82000

[ 12.004412]

[ 12.004530] CPU: 0 UID: 0 PID: 101 Comm: kworker/0:1H Not tainted 7.2.0-rc5-NVMECTL-gf5098b6bae76 #1 PREEMPT(lazy)

[ 12.005127] 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

[ 12.005762] Workqueue: kblockd blk_mq_run_work_fn

[ 12.006073] =====================================================

Allocate the page with __GFP_ZERO. The single allocation site covers

every use of it: bytes no discard has written stay zero, and bytes one

did write hold that controller's own range list, which it has already

been sent. (NVD)

What to Do

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

References