CVE-2025-38279

Published Jul 10, 2025

Last updated 3 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Do not include stack ptr register in precision backtracking bookkeeping Yi Lai reported an issue ([1]) where the following warning appears in kernel dmesg: [ 60.643604] verifier backtracking bug [ 60.643635] WARNING: CPU: 10 PID: 2315 at kernel/bpf/verifier.c:4302 __mark_chain_precision+0x3a6c/0x3e10 [ 60.648428] Modules linked in: bpf_testmod(OE) [ 60.650471] CPU: 10 UID: 0 PID: 2315 Comm: test_progs Tainted: G OE 6.15.0-rc4-gef11287f8289-dirty #327 PREEMPT(full) [ 60.654385] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [ 60.656682] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 60.660475] RIP: 0010:__mark_chain_precision+0x3a6c/0x3e10 [ 60.662814] Code: 5a 30 84 89 ea e8 c4 d9 01 00 80 3d 3e 7d d8 04 00 0f 85 60 fa ff ff c6 05 31 7d d8 04 01 48 c7 c7 00 58 30 84 e8 c4 06 a5 ff <0f> 0b e9 46 fa ff ff 48 ... [ 60.668720] RSP: 0018:ffff888116cc7298 EFLAGS: 00010246 [ 60.671075] RAX: 54d70e82dfd31900 RBX: ffff888115b65e20 RCX: 0000000000000000 [ 60.673659] RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000ffffffff [ 60.676241] RBP: 0000000000000400 R08: ffff8881f6f23bd3 R09: 1ffff1103ede477a [ 60.678787] R10: dffffc0000000000 R11: ffffed103ede477b R12: ffff888115b60ae8 [ 60.681420] R13: 1ffff11022b6cbc4 R14: 00000000fffffff2 R15: 0000000000000001 [ 60.684030] FS: 00007fc2aedd80c0(0000) GS:ffff88826fa8a000(0000) knlGS:0000000000000000 [ 60.686837] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 60.689027] CR2: 000056325369e000 CR3: 000000011088b002 CR4: 0000000000370ef0 [ 60.691623] Call Trace: [ 60.692821] <TASK> [ 60.693960] ? __pfx_verbose+0x10/0x10 [ 60.695656] ? __pfx_disasm_kfunc_name+0x10/0x10 [ 60.697495] check_cond_jmp_op+0x16f7/0x39b0 [ 60.699237] do_check+0x58fa/0xab10 ... Further analysis shows the warning is at line 4302 as below: 4294 /* static subprog call instruction, which 4295 * means that we are exiting current subprog, 4296 * so only r1-r5 could be still requested as 4297 * precise, r0 and r6-r10 or any stack slot in 4298 * the current frame should be zero by now 4299 */ 4300 if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) { 4301 verbose(env, "BUG regs %x\n", bt_reg_mask(bt)); 4302 WARN_ONCE(1, "verifier backtracking bug"); 4303 return -EFAULT; 4304 } With the below test (also in the next patch): __used __naked static void __bpf_jmp_r10(void) { asm volatile ( "r2 = 2314885393468386424 ll;" "goto +0;" "if r2 <= r10 goto +3;" "if r1 >= -1835016 goto +0;" "if r2 <= 8 goto +0;" "if r3 <= 0 goto +0;" "exit;" ::: __clobber_all); } SEC("?raw_tp") __naked void bpf_jmp_r10(void) { asm volatile ( "r3 = 0 ll;" "call __bpf_jmp_r10;" "r0 = 0;" "exit;" ::: __clobber_all); } The following is the verifier failure log: 0: (18) r3 = 0x0 ; R3_w=0 2: (85) call pc+2 caller: R10=fp0 callee: frame1: R1=ctx() R3_w=0 R10=fp0 5: frame1: R1=ctx() R3_w=0 R10=fp0 ; asm volatile (" \ @ verifier_precision.c:184 5: (18) r2 = 0x20202000256c6c78 ; frame1: R2_w=0x20202000256c6c78 7: (05) goto pc+0 8: (bd) if r2 <= r10 goto pc+3 ; frame1: R2_w=0x20202000256c6c78 R10=fp0 9: (35) if r1 >= 0xffe3fff8 goto pc+0 ; frame1: R1=ctx() 10: (b5) if r2 <= 0x8 goto pc+0 mark_precise: frame1: last_idx 10 first_idx 0 subseq_idx -1 mark_precise: frame1: regs=r2 stack= before 9: (35) if r1 >= 0xffe3fff8 goto pc+0 mark_precise: frame1: regs=r2 stack= before 8: (bd) if r2 <= r10 goto pc+3 mark_preci ---truncated---
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
7.8
Impact score
5.9
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: coresight: tmc-etr: Fix race condition between sysfs and perf mode When trying to run perf and sysfs mode simultaneously, the WARN_ON() in tmc_etr_enable_hw() is triggered sometimes: WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] [..snip..] Call trace: tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] coresight_enable_path+0x1c8/0x218 [coresight] coresight_enable_sysfs+0xa4/0x228 [coresight] enable_source_store+0x58/0xa8 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2c8/0x388 ksys_write+0x74/0x108 __arm64_sys_write+0x24/0x38 el0_svc_common.constprop.0+0x64/0x148 do_el0_svc+0x24/0x38 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xc8/0xd0 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Since the enablement of sysfs mode is separeted into two critical regions, one for sysfs buffer allocation and another for hardware enablement, it's possible to race with the perf mode. Fix this by double check whether the perf mode's been used before enabling the hardware in sysfs mode. mode: [sysfs mode] [perf mode] tmc_etr_get_sysfs_buffer() spin_lock(&drvdata->spinlock) [sysfs buffer allocation] spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() drvdata->etr_buf = etr_perf->etr_buf spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at the perf side spin_unlock(&drvdata->spinlock) With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf. This ensures we verify whether the perf mode's already running before we actually allocate the buffer. Then we can save the time of allocating/freeing the sysfs buffer if race with the perf mode.CVE-2026-46272