Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off for validation. However, variable offset ptr alu is not prohibited for this ptr kind. So the variable offset is not checked. The following prog is accepted: func#0 @0 0: R1=ctx() R10=fp0 0: (bf) r6 = r1 ; R1=ctx() R6_w=ctx() 1: (79) r7 = *(u64 *)(r6 +144) ; R6_w=ctx() R7_w=flow_keys() 2: (b7) r8 = 1024 ; R8_w=1024 3: (37) r8 /= 1 ; R8_w=scalar() 4: (57) r8 &= 1024 ; R8_w=scalar(smin=smin32=0, smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400)) 5: (0f) r7 += r8 mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1 mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024 mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1 mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024 6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off =(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024, var_off=(0x0; 0x400)) 6: (79) r0 = *(u64 *)(r7 +0) ; R0_w=scalar() 7: (95) exit This prog loads flow_keys to r7, and adds the variable offset r8 to r7, and finally causes out-of-bounds access: BUG: unable to handle page fault for address: ffffc90014c80038 [...] Call Trace: bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline] __bpf_prog_run include/linux/filter.h:651 [inline] bpf_prog_run include/linux/filter.h:658 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline] bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991 bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359 bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline] __sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475 __do_sys_bpf kernel/bpf/syscall.c:5561 [inline] __se_sys_bpf kernel/bpf/syscall.c:5559 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Fix this by rejecting ptr alu with variable offset on flow_keys. Applying the patch rejects the program with "R7 pointer arithmetic on flow_keys prohibited".
Details
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 5.15.0-102.112 |
| linux-allwinner-5.19 | — | — |
| linux-aws | — | 5.15.0-1057.63 |
| linux-aws-5.0 | — | — |
| linux-aws-5.11 | — | — |
| linux-aws-5.13 | — | — |
| linux-aws-5.15 | — | 5.15.0-1057.63~20.04.1 |
| linux-aws-5.19 | — | — |
| linux-aws-5.3 | — | — |
| linux-aws-5.4 | — | 5.4.0-1123.133~18.04.1 |
| linux-aws-5.8 | — | — |
| linux-aws-6.2 | — | — |
| linux-aws-6.5 | — | 6.5.0-1018.18~22.04.1 |
| linux-aws-fips | — | 5.15.0-1057.63+fips1 |
| linux-azure | — | 5.15.0-1060.69 |
| linux-azure-5.11 | — | — |
| linux-azure-5.13 | — | — |
| linux-azure-5.15 | — | 5.15.0-1060.69~20.04.1 |
| linux-azure-5.19 | — | — |
| linux-azure-5.3 | — | — |
| linux-azure-5.4 | — | 5.4.0-1128.135~18.04.1 |
| linux-azure-5.8 | — | — |
| linux-azure-6.2 | — | — |
| linux-azure-6.5 | — | 6.5.0-1019.20~22.04.1 |
| linux-azure-edge | — | — |
| linux-azure-fde | — | — |
| linux-azure-fde-5.19 | — | — |
| linux-azure-fde-6.2 | — | — |
| linux-azure-fde-6.8 | — | — |
| linux-azure-fips | — | 5.15.0-1060.69+fips1 |
| linux-bluefield | — | — |
| linux-fips | — | 5.15.0-102.112+fips1 |
| linux-gcp | — | 5.15.0-1055.63 |
| linux-gcp-5.11 | — | — |
| linux-gcp-5.13 | — | — |
| linux-gcp-5.15 | — | 5.15.0-1055.63~20.04.1 |
| linux-gcp-5.19 | — | — |
| linux-gcp-5.3 | — | — |
| linux-gcp-5.4 | — | 5.4.0-1127.136~18.04.1 |
| linux-gcp-5.8 | — | — |
| linux-gcp-6.2 | — | — |
| linux-gcp-6.5 | — | 6.5.0-1018.18~22.04.1 |
| linux-gcp-fips | — | 5.15.0-1055.63+fips2 |
| linux-gke | — | 5.15.0-1054.59 |
| linux-gke-4.15 | — | — |
| linux-gke-5.15 | — | — |
| linux-gke-5.4 | — | — |
| linux-gkeop | — | 5.15.0-1040.46 |
| linux-gkeop-5.15 | — | 5.15.0-1040.46~20.04.1 |
| linux-gkeop-5.4 | — | — |
| linux-hwe | — | — |
| linux-hwe-5.11 | — | — |
| linux-hwe-5.13 | — | — |
| linux-hwe-5.15 | — | 5.15.0-102.112~20.04.1 |
| linux-hwe-5.19 | — | — |
| linux-hwe-5.4 | — | 5.4.0-177.197~18.04.1 |
| linux-hwe-5.8 | — | — |
| linux-hwe-6.2 | — | — |
| linux-hwe-6.5 | — | 6.5.0-28.29~22.04.1 |
| linux-hwe-edge | — | — |
| linux-ibm | — | 5.15.0-1050.53 |
| linux-ibm-5.15 | — | 5.15.0-1050.53~20.04.1 |
| linux-ibm-5.4 | — | 5.4.0-1070.75~18.04.1 |
| linux-intel-5.13 | — | — |
| linux-intel-iot-realtime | — | 5.15.0-1050.52 |
| linux-intel-iotg | — | 5.15.0-1052.58 |
| linux-intel-iotg-5.15 | — | 5.15.0-1052.58~20.04.1 |
| linux-iot | — | 5.4.0-1035.36 |
| linux-kvm | — | 5.15.0-1054.59 |
| linux-lowlatency | — | 5.15.0-102.112 |
| linux-lowlatency-hwe-5.15 | — | 5.15.0-102.112~20.04.1 |
| linux-lowlatency-hwe-5.19 | — | — |
| linux-lowlatency-hwe-6.2 | — | — |
| linux-lowlatency-hwe-6.5 | — | 6.5.0-28.29.1~22.04.1 |
| linux-nvidia | — | 5.15.0-1048.48 |
| linux-nvidia-6.2 | — | — |
| linux-nvidia-6.5 | — | 6.5.0-1015.15 |
| linux-nvidia-tegra | — | 5.15.0-1025.25 |
| linux-nvidia-tegra-5.15 | — | 5.15.0-1025.25~20.04.1 |
| linux-nvidia-tegra-igx | — | 5.15.0-1012.12 |
| linux-oem | — | — |
| linux-oem-5.10 | — | — |
| linux-oem-5.13 | — | — |
| linux-oem-5.14 | — | — |
| linux-oem-5.17 | — | — |
| linux-oem-5.6 | — | — |
| linux-oem-6.0 | — | — |
| linux-oem-6.1 | — | 6.1.0-1035.35 |
| linux-oem-6.5 | — | 6.5.0-1020.21 |
| linux-oracle | — | 5.15.0-1055.61 |
| linux-oracle-5.0 | — | — |
| linux-oracle-5.11 | — | — |
| linux-oracle-5.13 | — | — |
| linux-oracle-5.15 | — | 5.15.0-1055.61~20.04.1 |
| linux-oracle-5.3 | — | — |
| linux-oracle-5.4 | — | 5.4.0-1122.131~18.04.1 |
| linux-oracle-5.8 | — | — |
| linux-oracle-6.5 | — | 6.5.0-1021.21~22.04.1 |
| linux-raspi | — | 5.15.0-1050.53 |
| linux-raspi-5.4 | — | 5.4.0-1107.119~18.04.1 |
| linux-raspi-realtime | — | 6.8.0-2001.1 |
| linux-raspi2 | — | — |
| linux-realtime | — | 5.15.0-1058.66 |
| linux-riscv | — | — |
| linux-riscv-5.11 | — | — |
| linux-riscv-5.15 | — | 5.15.0-1053.57~20.04.1 |
| linux-riscv-5.19 | — | — |
| linux-riscv-5.8 | — | — |
| linux-riscv-6.5 | — | 6.5.0-28.29.1~22.04.1 |
| linux-starfive-5.19 | — | — |
| linux-starfive-6.2 | — | — |
| linux-starfive-6.5 | — | 6.5.0-1012.13~22.04.1 |
| linux-xilinx-zynqmp | — | 5.15.0-1030.34 |
References
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