fkie_cve-2023-53634
Vulnerability from fkie_nvd
Published
2025-10-07 16:15
Modified
2025-10-08 19:38
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Fixed a BTI error on returning to patched function When BPF_TRAMP_F_CALL_ORIG is set, BPF trampoline uses BLR to jump back to the instruction next to call site to call the patched function. For BTI-enabled kernel, the instruction next to call site is usually PACIASP, in this case, it's safe to jump back with BLR. But when the call site is not followed by a PACIASP or bti, a BTI exception is triggered. Here is a fault log: Unhandled 64-bit el1h sync exception on CPU0, ESR 0x0000000034000002 -- BTI CPU: 0 PID: 263 Comm: test_progs Tainted: GF Hardware name: linux,dummy-virt (DT) pstate: 40400805 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=-c) pc : bpf_fentry_test1+0xc/0x30 lr : bpf_trampoline_6442573892_0+0x48/0x1000 sp : ffff80000c0c3a50 x29: ffff80000c0c3a90 x28: ffff0000c2e6c080 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000050 x23: 0000000000000000 x22: 0000ffffcfd2a7f0 x21: 000000000000000a x20: 0000ffffcfd2a7f0 x19: 0000000000000000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffffcfd2a7f0 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: ffff80000914f5e4 x9 : ffff8000082a1528 x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0101010101010101 x5 : 0000000000000000 x4 : 00000000fffffff2 x3 : 0000000000000001 x2 : ffff8001f4b82000 x1 : 0000000000000000 x0 : 0000000000000001 Kernel panic - not syncing: Unhandled exception CPU: 0 PID: 263 Comm: test_progs Tainted: GF Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0xec/0x144 show_stack+0x24/0x7c dump_stack_lvl+0x8c/0xb8 dump_stack+0x18/0x34 panic+0x1cc/0x3ec __el0_error_handler_common+0x0/0x130 el1h_64_sync_handler+0x60/0xd0 el1h_64_sync+0x78/0x7c bpf_fentry_test1+0xc/0x30 bpf_fentry_test1+0xc/0x30 bpf_prog_test_run_tracing+0xdc/0x2a0 __sys_bpf+0x438/0x22a0 __arm64_sys_bpf+0x30/0x54 invoke_syscall+0x78/0x110 el0_svc_common.constprop.0+0x6c/0x1d0 do_el0_svc+0x38/0xe0 el0_svc+0x30/0xd0 el0t_64_sync_handler+0x1ac/0x1b0 el0t_64_sync+0x1a0/0x1a4 Kernel Offset: disabled CPU features: 0x0000,00034c24,f994fdab Memory Limit: none And the instruction next to call site of bpf_fentry_test1 is ADD, not PACIASP: <bpf_fentry_test1>: bti c nop nop add w0, w0, #0x1 paciasp For BPF prog, JIT always puts a PACIASP after call site for BTI-enabled kernel, so there is no problem. To fix it, replace BLR with RET to bypass the branch target check.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/738a96c4a8c36950803fdd27e7c30aca92dccefd
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8b9c64942ada229f52fe6f1b537a50f88b3c2673
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/eabc166919d169e105263974991f52b0351e431a
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, arm64: Fixed a BTI error on returning to patched function\n\nWhen BPF_TRAMP_F_CALL_ORIG is set, BPF trampoline uses BLR to jump\nback to the instruction next to call site to call the patched function.\nFor BTI-enabled kernel, the instruction next to call site is usually\nPACIASP, in this case, it\u0027s safe to jump back with BLR. But when\nthe call site is not followed by a PACIASP or bti, a BTI exception\nis triggered.\n\nHere is a fault log:\n\n Unhandled 64-bit el1h sync exception on CPU0, ESR 0x0000000034000002 -- BTI\n CPU: 0 PID: 263 Comm: test_progs Tainted: GF\n Hardware name: linux,dummy-virt (DT)\n pstate: 40400805 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=-c)\n pc : bpf_fentry_test1+0xc/0x30\n lr : bpf_trampoline_6442573892_0+0x48/0x1000\n sp : ffff80000c0c3a50\n x29: ffff80000c0c3a90 x28: ffff0000c2e6c080 x27: 0000000000000000\n x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000050\n x23: 0000000000000000 x22: 0000ffffcfd2a7f0 x21: 000000000000000a\n x20: 0000ffffcfd2a7f0 x19: 0000000000000000 x18: 0000000000000000\n x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffffcfd2a7f0\n x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000\n x11: 0000000000000000 x10: ffff80000914f5e4 x9 : ffff8000082a1528\n x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0101010101010101\n x5 : 0000000000000000 x4 : 00000000fffffff2 x3 : 0000000000000001\n x2 : ffff8001f4b82000 x1 : 0000000000000000 x0 : 0000000000000001\n Kernel panic - not syncing: Unhandled exception\n CPU: 0 PID: 263 Comm: test_progs Tainted: GF\n Hardware name: linux,dummy-virt (DT)\n Call trace:\n  dump_backtrace+0xec/0x144\n  show_stack+0x24/0x7c\n  dump_stack_lvl+0x8c/0xb8\n  dump_stack+0x18/0x34\n  panic+0x1cc/0x3ec\n  __el0_error_handler_common+0x0/0x130\n  el1h_64_sync_handler+0x60/0xd0\n  el1h_64_sync+0x78/0x7c\n  bpf_fentry_test1+0xc/0x30\n  bpf_fentry_test1+0xc/0x30\n  bpf_prog_test_run_tracing+0xdc/0x2a0\n  __sys_bpf+0x438/0x22a0\n  __arm64_sys_bpf+0x30/0x54\n  invoke_syscall+0x78/0x110\n  el0_svc_common.constprop.0+0x6c/0x1d0\n  do_el0_svc+0x38/0xe0\n  el0_svc+0x30/0xd0\n  el0t_64_sync_handler+0x1ac/0x1b0\n  el0t_64_sync+0x1a0/0x1a4\n Kernel Offset: disabled\n CPU features: 0x0000,00034c24,f994fdab\n Memory Limit: none\n\nAnd the instruction next to call site of bpf_fentry_test1 is ADD,\nnot PACIASP:\n\n\u003cbpf_fentry_test1\u003e:\n\tbti     c\n\tnop\n\tnop\n\tadd     w0, w0, #0x1\n\tpaciasp\n\nFor BPF prog, JIT always puts a PACIASP after call site for BTI-enabled\nkernel, so there is no problem. To fix it, replace BLR with RET to bypass\nthe branch target check."
    }
  ],
  "id": "CVE-2023-53634",
  "lastModified": "2025-10-08T19:38:32.610",
  "metrics": {},
  "published": "2025-10-07T16:15:46.523",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/738a96c4a8c36950803fdd27e7c30aca92dccefd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8b9c64942ada229f52fe6f1b537a50f88b3c2673"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/eabc166919d169e105263974991f52b0351e431a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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