CVE-2022-50553
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-07

Last updated on: 2026-02-04

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: tracing/hist: Fix out-of-bound write on 'action_data.var_ref_idx' When generate a synthetic event with many params and then create a trace action for it [1], kernel panic happened [2]. It is because that in trace_action_create() 'data->n_params' is up to SYNTH_FIELDS_MAX (current value is 64), and array 'data->var_ref_idx' keeps indices into array 'hist_data->var_refs' for each synthetic event param, but the length of 'data->var_ref_idx' is TRACING_MAP_VARS_MAX (current value is 16), so out-of-bound write happened when 'data->n_params' more than 16. In this case, 'data->match_data.event' is overwritten and eventually cause the panic. To solve the issue, adjust the length of 'data->var_ref_idx' to be SYNTH_FIELDS_MAX and add sanity checks to avoid out-of-bound write. [1] # cd /sys/kernel/tracing/ # echo "my_synth_event int v1; int v2; int v3; int v4; int v5; int v6;\ int v7; int v8; int v9; int v10; int v11; int v12; int v13; int v14;\ int v15; int v16; int v17; int v18; int v19; int v20; int v21; int v22;\ int v23; int v24; int v25; int v26; int v27; int v28; int v29; int v30;\ int v31; int v32; int v33; int v34; int v35; int v36; int v37; int v38;\ int v39; int v40; int v41; int v42; int v43; int v44; int v45; int v46;\ int v47; int v48; int v49; int v50; int v51; int v52; int v53; int v54;\ int v55; int v56; int v57; int v58; int v59; int v60; int v61; int v62;\ int v63" >> synthetic_events # echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="bash"' >> \ events/sched/sched_waking/trigger # echo "hist:keys=next_pid:onmatch(sched.sched_waking).my_synth_event(\ pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,\ pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,\ pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,\ pid,pid,pid,pid,pid,pid,pid,pid,pid)" >> events/sched/sched_switch/trigger [2] BUG: unable to handle page fault for address: ffff91c900000000 PGD 61001067 P4D 61001067 PUD 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 2 PID: 322 Comm: bash Tainted: G W 6.1.0-rc8+ #229 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014 RIP: 0010:strcmp+0xc/0x30 Code: 75 f7 31 d2 44 0f b6 04 16 44 88 04 11 48 83 c2 01 45 84 c0 75 ee c3 cc cc cc cc 0f 1f 00 31 c0 eb 08 48 83 c0 01 84 d2 74 13 <0f> b6 14 07 3a 14 06 74 ef 19 c0 83 c8 01 c3 cc cc cc cc 31 c3 RSP: 0018:ffff9b3b00f53c48 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffffba958a68 RCX: 0000000000000000 RDX: 0000000000000010 RSI: ffff91c943d33a90 RDI: ffff91c900000000 RBP: ffff91c900000000 R08: 00000018d604b529 R09: 0000000000000000 R10: ffff91c9483eddb1 R11: ffff91ca483eddab R12: ffff91c946171580 R13: ffff91c9479f0538 R14: ffff91c9457c2848 R15: ffff91c9479f0538 FS: 00007f1d1cfbe740(0000) GS:ffff91c9bdc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff91c900000000 CR3: 0000000006316000 CR4: 00000000000006e0 Call Trace: <TASK> __find_event_file+0x55/0x90 action_create+0x76c/0x1060 event_hist_trigger_parse+0x146d/0x2060 ? event_trigger_write+0x31/0xd0 trigger_process_regex+0xbb/0x110 event_trigger_write+0x6b/0xd0 vfs_write+0xc8/0x3e0 ? alloc_fd+0xc0/0x160 ? preempt_count_add+0x4d/0xa0 ? preempt_count_add+0x70/0xa0 ksys_write+0x5f/0xe0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f1d1d0cf077 Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 RSP: 002b:00007ffcebb0e568 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000143 RCX: 00007f1d1d0cf077 RDX: 0000000000000143 RSI: 00005639265aa7e0 RDI: 0000000000000001 RBP: 00005639265aa7e0 R08: 000000000000000a R09: 0000000000000142 R ---truncated---
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Meta Information
Published
2025-10-07
Last Modified
2026-02-04
Generated
2026-05-07
AI Q&A
2025-10-07
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.11 (inc) to 5.15.87 (inc)
linux linux_kernel 6.1.0-rc8
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is an out-of-bound write in the Linux kernel's tracing subsystem. Specifically, when creating a synthetic event with many parameters (more than 16), the kernel writes beyond the bounds of an array called 'var_ref_idx' which only supports up to 16 entries, while the number of parameters can be up to 64. This causes memory corruption that overwrites other data structures, eventually leading to a kernel panic (system crash). The issue was fixed by increasing the array size and adding checks to prevent out-of-bound writes.


How can this vulnerability impact me? :

This vulnerability can cause a kernel panic, which means the affected Linux system can crash unexpectedly. This can lead to denial of service, loss of availability, and potential data loss or corruption if the system is unstable or crashes during critical operations.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by attempting to create a synthetic event with more than 16 parameters in the Linux kernel tracing subsystem, which triggers the out-of-bound write and kernel panic. The following commands can be used to test for the vulnerability by creating such an event and trace action: # cd /sys/kernel/tracing/ # echo "my_synth_event int v1; int v2; int v3; int v4; int v5; int v6; int v7; int v8; int v9; int v10; int v11; int v12; int v13; int v14; int v15; int v16; int v17; int v18; int v19; int v20; int v21; int v22; int v23; int v24; int v25; int v26; int v27; int v28; int v29; int v30; int v31; int v32; int v33; int v34; int v35; int v36; int v37; int v38; int v39; int v40; int v41; int v42; int v43; int v44; int v45; int v46; int v47; int v48; int v49; int v50; int v51; int v52; int v53; int v54; int v55; int v56; int v57; int v58; int v59; int v60; int v61; int v62; int v63" >> synthetic_events # echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="bash"' >> events/sched/sched_waking/trigger # echo "hist:keys=next_pid:onmatch(sched.sched_waking).my_synth_event(pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid,pid)" >> events/sched/sched_switch/trigger If these commands cause a kernel panic or similar crash, the system is vulnerable.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include updating the Linux kernel to a version where this vulnerability is fixed. The fix involves adjusting the length of the 'data->var_ref_idx' array to match SYNTH_FIELDS_MAX and adding sanity checks to prevent out-of-bound writes. Until the kernel is updated, avoid creating synthetic events with more than 16 parameters in the tracing subsystem to prevent triggering the vulnerability.


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