CVE-2025-38279

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> bpf: Do not include stack ptr register in precision backtracking bookkeeping<br /> <br /> Yi Lai reported an issue ([1]) where the following warning appears<br /> in kernel dmesg:<br /> [ 60.643604] verifier backtracking bug<br /> [ 60.643635] WARNING: CPU: 10 PID: 2315 at kernel/bpf/verifier.c:4302 __mark_chain_precision+0x3a6c/0x3e10<br /> [ 60.648428] Modules linked in: bpf_testmod(OE)<br /> [ 60.650471] CPU: 10 UID: 0 PID: 2315 Comm: test_progs Tainted: G OE 6.15.0-rc4-gef11287f8289-dirty #327 PREEMPT(full)<br /> [ 60.654385] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE<br /> [ 60.656682] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014<br /> [ 60.660475] RIP: 0010:__mark_chain_precision+0x3a6c/0x3e10<br /> [ 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<br /> 01 48 c7 c7 00 58 30 84 e8 c4 06 a5 ff 0b e9 46 fa ff ff 48 ...<br /> [ 60.668720] RSP: 0018:ffff888116cc7298 EFLAGS: 00010246<br /> [ 60.671075] RAX: 54d70e82dfd31900 RBX: ffff888115b65e20 RCX: 0000000000000000<br /> [ 60.673659] RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000ffffffff<br /> [ 60.676241] RBP: 0000000000000400 R08: ffff8881f6f23bd3 R09: 1ffff1103ede477a<br /> [ 60.678787] R10: dffffc0000000000 R11: ffffed103ede477b R12: ffff888115b60ae8<br /> [ 60.681420] R13: 1ffff11022b6cbc4 R14: 00000000fffffff2 R15: 0000000000000001<br /> [ 60.684030] FS: 00007fc2aedd80c0(0000) GS:ffff88826fa8a000(0000) knlGS:0000000000000000<br /> [ 60.686837] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> [ 60.689027] CR2: 000056325369e000 CR3: 000000011088b002 CR4: 0000000000370ef0<br /> [ 60.691623] Call Trace:<br /> [ 60.692821] <br /> [ 60.693960] ? __pfx_verbose+0x10/0x10<br /> [ 60.695656] ? __pfx_disasm_kfunc_name+0x10/0x10<br /> [ 60.697495] check_cond_jmp_op+0x16f7/0x39b0<br /> [ 60.699237] do_check+0x58fa/0xab10<br /> ...<br /> <br /> Further analysis shows the warning is at line 4302 as below:<br /> <br /> 4294 /* static subprog call instruction, which<br /> 4295 * means that we are exiting current subprog,<br /> 4296 * so only r1-r5 could be still requested as<br /> 4297 * precise, r0 and r6-r10 or any stack slot in<br /> 4298 * the current frame should be zero by now<br /> 4299 */<br /> 4300 if (bt_reg_mask(bt) &amp; ~BPF_REGMASK_ARGS) {<br /> 4301 verbose(env, "BUG regs %x\n", bt_reg_mask(bt));<br /> 4302 WARN_ONCE(1, "verifier backtracking bug");<br /> 4303 return -EFAULT;<br /> 4304 }<br /> <br /> With the below test (also in the next patch):<br /> __used __naked static void __bpf_jmp_r10(void)<br /> {<br /> asm volatile (<br /> "r2 = 2314885393468386424 ll;"<br /> "goto +0;"<br /> "if r2 = -1835016 goto +0;"<br /> "if r2