| Message ID | 20240322153518.11555-1-puranjay12@gmail.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | [bpf,v2] bpf: verifier: reject addr_space_cast insn without arena | expand |
Hello: This patch was applied to bpf/bpf.git (master) by Alexei Starovoitov <ast@kernel.org>: On Fri, 22 Mar 2024 15:35:18 +0000 you wrote: > The verifier allows using the addr_space_cast instruction in a program > that doesn't have an associated arena. This was caught in the form an > invalid memory access in do_misc_fixups() when while converting > addr_space_cast to a normal 32-bit mov, env->prog->aux->arena was > dereferenced to check for BPF_F_NO_USER_CONV flag. > > Reject programs that include the addr_space_cast instruction but don't > have an associated arena. > > [...] Here is the summary with links: - [bpf,v2] bpf: verifier: reject addr_space_cast insn without arena https://git.kernel.org/bpf/bpf/c/122fdbd2a030 You are awesome, thank you!
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ca6cacf7b42f..7d0bbee10d71 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14014,6 +14014,10 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) verbose(env, "addr_space_cast insn can only convert between address space 1 and 0\n"); return -EINVAL; } + if (!env->prog->aux->arena) { + verbose(env, "addr_space_cast insn can only be used in a program that has an associated arena\n"); + return -EINVAL; + } } else { if ((insn->off != 0 && insn->off != 8 && insn->off != 16 && insn->off != 32) || insn->imm) {
The verifier allows using the addr_space_cast instruction in a program that doesn't have an associated arena. This was caught in the form an invalid memory access in do_misc_fixups() when while converting addr_space_cast to a normal 32-bit mov, env->prog->aux->arena was dereferenced to check for BPF_F_NO_USER_CONV flag. Reject programs that include the addr_space_cast instruction but don't have an associated arena. root@rv-tester:~# ./reproducer Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000030 Oops [#1] Modules linked in: sch_fq_codel drm fuse i2c_core drm_panel_orientation_quirks backlight configfs ip_tables x_tables CPU: 2 PID: 265 Comm: reproducer Not tainted 6.8.0 #3 Hardware name: riscv-virtio,qemu (DT) epc : do_misc_fixups+0x43c/0x1168 ra : bpf_check+0xda8/0x22b6 epc : ffffffff8017eeaa ra : ffffffff801936d6 sp : ff200000011bb890 gp : ffffffff82293468 tp : ff60000084fcb840 t0 : ff60000084e38048 t1 : 0000000000000048 t2 : ff5fffff80000000 s0 : ff200000011bba60 s1 : ff2000000101d058 a0 : ff6000008b980000 a1 : 0000000000000004 a2 : 00000000000000e1 a3 : 0000000000000001 a4 : 0000000000010000 a5 : 0000000000000000 a6 : 0000000000000001 a7 : ff2000000101d000 s2 : 0000000000000002 s3 : 0000000000000000 s4 : 0000000000000000 s5 : 0000000000000002 s6 : 0000000000000000 s7 : ff6000008b980aa0 s8 : 0000000000010005 s9 : 0000000000000004 s10: ff6000008b980000 s11: 0000000000000000 t3 : 0000000000002000 t4 : 0000ff0000000000 t5 : 00ff000000000000 t6 : ff20000000000000 status: 0000000200000120 badaddr: 0000000000000030 cause: 000000000000000d [<ffffffff8017eeaa>] do_misc_fixups+0x43c/0x1168 [<ffffffff801936d6>] bpf_check+0xda8/0x22b6 [<ffffffff80174b32>] bpf_prog_load+0x486/0x8dc [<ffffffff80176566>] __sys_bpf+0xbd8/0x214e [<ffffffff80177d14>] __riscv_sys_bpf+0x22/0x2a [<ffffffff80d2493a>] do_trap_ecall_u+0x102/0x17c [<ffffffff80d3048c>] ret_from_exception+0x0/0x64 Code: b345 9783 0024 4685 8b63 16d7 3783 008d 7f9c 7fdc (5b9c) 83c9 ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Fatal exception SMP: stopping secondary CPUs Fixes: 6082b6c328b5 ("bpf: Recognize addr_space_cast instruction in the verifier.") Reported-by: xingwei lee <xrivendell7@gmail.com> Reported-by: yue sun <samsun1006219@gmail.com> Closes: https://lore.kernel.org/bpf/CABOYnLz09O1+2gGVJuCxd_24a-7UueXzV-Ff+Fr+h5EKFDiYCQ@mail.gmail.com/ Signed-off-by: Puranjay Mohan <puranjay12@gmail.com> --- Changes in V2: V1: https://lore.kernel.org/bpf/20240322143829.40808-1-puranjay12@gmail.com/ - Reject programs that have the addr_space_cast instruction without an arena rather than checking for a NULL pointer in do_misc_fixups. --- kernel/bpf/verifier.c | 4 ++++ 1 file changed, 4 insertions(+)