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authorPuranjay Mohan <puranjay12@gmail.com>2024-03-22 15:35:18 +0000
committerAlexei Starovoitov <ast@kernel.org>2024-03-22 20:44:09 -0700
commit122fdbd2a030a95128737fc77e47df15a8f170c3 (patch)
tree1fe529947757590ccdc1537f14cb712f054b5141 /kernel
parentfa3550dca8f02ec312727653a94115ef3ab68445 (diff)
bpf: verifier: reject addr_space_cast insn without arena
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] [<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 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> Link: https://lore.kernel.org/r/20240322153518.11555-1-puranjay12@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2cd7e0e79283..0bfc0050db28 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -14022,6 +14022,10 @@ 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) {