CVE-2025-38279 Information

Jul 12, 2025 cve

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] [ 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 erifier 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 (

2 = 2314885393468386424 ll;\n \goto +0;\n \if r2 <= r10 goto +3;\n \if r1 >= -1835016 goto +0;\n \if r2 <= 8 goto +0;\n \if r3 <= 0 goto +0;\n xit;\n ::: __clobber_all);

SEC(?raw_tp) __naked void bpf_jmp_r10(void)

asm volatile (

3 = 0 ll;\n ## Reference https://git.kernel.org/stable/c/4265682c29c92f52c0da6fad5a79b5801462c8de https://git.kernel.org/stable/c/ac49b7560b4b08b1e4043a29214cc7ad77644c00 https://git.kernel.org/stable/c/e2d2115e56c4a02377189bfc3a9a7933552a7b0f

CNNVD-202507-1405 (Published: 2025-07-10)

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