{ "threat_severity" : "Low", "public_date" : "2026-03-25T00:00:00Z", "bugzilla" : { "description" : "kernel: blktrace: fix __this_cpu_read/write in preemptible context", "id" : "2451165", "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2451165" }, "cvss3" : { "cvss3_base_score" : "5.5", "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status" : "draft" }, "cwe" : "CWE-820", "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nblktrace: fix __this_cpu_read/write in preemptible context\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__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:\nblktrace/002 (blktrace ftrace corruption with sysfs trace) [failed]\nruntime 0.367s ... 0.437s\nsomething 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] \n[ 81.362886] dump_stack_lvl+0x8d/0xb0\n...\n(See '/mnt/sda/blktests/results/nodev/blktrace/002.dmesg' for the entire message)\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] \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] \nThe same BUG fires from blk_add_trace_plug(), blk_add_trace_unplug(),\nand blk_add_trace_rq() paths as well.\nThe purpose of tracin\n---truncated---", "A flaw was found in the Linux kernel's blktrace component. This vulnerability arises when the `tracing_record_cmdline()` function attempts to access a per-CPU variable in a preemptible context, which is an unsafe operation. A local attacker could exploit this to trigger a kernel bug, potentially leading to system instability or a denial of service (DoS)." ], "package_state" : [ { "product_name" : "Red Hat Enterprise Linux 10", "fix_state" : "Fix deferred", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:10" }, { "product_name" : "Red Hat Enterprise Linux 6", "fix_state" : "Out of support scope", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:6" }, { "product_name" : "Red Hat Enterprise Linux 7", "fix_state" : "Fix deferred", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:7" }, { "product_name" : "Red Hat Enterprise Linux 7", "fix_state" : "Fix deferred", "package_name" : "kernel-rt", "cpe" : "cpe:/o:redhat:enterprise_linux:7" }, { "product_name" : "Red Hat Enterprise Linux 8", "fix_state" : "Fix deferred", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:8" }, { "product_name" : "Red Hat Enterprise Linux 8", "fix_state" : "Fix deferred", "package_name" : "kernel-rt", "cpe" : "cpe:/o:redhat:enterprise_linux:8" }, { "product_name" : "Red Hat Enterprise Linux 9", "fix_state" : "Fix deferred", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:9" }, { "product_name" : "Red Hat Enterprise Linux 9", "fix_state" : "Fix deferred", "package_name" : "kernel-rt", "cpe" : "cpe:/o:redhat:enterprise_linux:9" } ], "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-23374\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23374\nhttps://lore.kernel.org/linux-cve-announce/2026032541-CVE-2026-23374-9345@gregkh/T" ], "name" : "CVE-2026-23374", "csaw" : false }