From: Kurt Manucredo <fuzzybritches0@gmail.com>
To: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com
Cc: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
daniel@iogearbox.net, davem@davemloft.net, hawk@kernel.org,
john.fastabend@gmail.com, kafai@fb.com, kpsingh@kernel.org,
kuba@kernel.org, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, songliubraving@fb.com,
syzkaller-bugs@googlegroups.com, yhs@fb.com, nathan@kernel.org,
ndesaulniers@google.com, clang-built-linux@googlegroups.com,
linux-kernel-mentees@lists.linuxfoundation.org,
skhan@linuxfoundation.org, gregkh@linuxfoundation.org,
Kurt Manucredo <fuzzybritches0@gmail.com>
Subject: [PATCH v3] bpf: core: fix shift-out-of-bounds in ___bpf_prog_run
Date: Wed, 2 Jun 2021 21:27:26 +0000 [thread overview]
Message-ID: <20210602212726.7-1-fuzzybritches0@gmail.com> (raw)
In-Reply-To: <000000000000c2987605be907e41@google.com>
UBSAN: shift-out-of-bounds in kernel/bpf/core.c:1414:2
shift exponent 248 is too large for 32-bit type 'unsigned int'
Reported-and-tested-by: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com
Signed-off-by: Kurt Manucredo <fuzzybritches0@gmail.com>
---
https://syzkaller.appspot.com/bug?id=edb51be4c9a320186328893287bb30d5eed09231
Changelog:
----------
v3 - Make it clearer what the fix is for.
v2 - Fix shift-out-of-bounds in ___bpf_prog_run() by adding boundary
check in check_alu_op() in verifier.c.
v1 - Fix shift-out-of-bounds in ___bpf_prog_run() by adding boundary
check in ___bpf_prog_run().
Hi everyone,
I hope this fixes it!
kind regards
kernel/bpf/verifier.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 94ba5163d4c5..04e3bf344ecd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7880,13 +7880,25 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
return -EINVAL;
}
- if ((opcode == BPF_LSH || opcode == BPF_RSH ||
- opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
+ if (opcode == BPF_LSH || opcode == BPF_RSH ||
+ opcode == BPF_ARSH) {
int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
- if (insn->imm < 0 || insn->imm >= size) {
- verbose(env, "invalid shift %d\n", insn->imm);
- return -EINVAL;
+ if (BPF_SRC(insn->code) == BPF_K) {
+ if (insn->imm < 0 || insn->imm >= size) {
+ verbose(env, "invalid shift %d\n", insn->imm);
+ return -EINVAL;
+ }
+ }
+ if (BPF_SRC(insn->code) == BPF_X) {
+ struct bpf_reg_state *src_reg;
+
+ src_reg = ®s[insn->src_reg];
+ if (src_reg->umax_value >= size) {
+ verbose(env, "invalid shift %lld\n",
+ src_reg->umax_value);
+ return -EINVAL;
+ }
}
}
--
2.30.2
next prev parent reply other threads:[~2021-06-02 21:30 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 16:05 [syzbot] UBSAN: shift-out-of-bounds in ___bpf_prog_run syzbot
2021-03-28 3:38 ` syzbot
2021-06-02 21:27 ` Kurt Manucredo [this message]
2021-06-03 4:43 ` [PATCH v3] bpf: core: fix " Greg KH
2021-06-05 15:01 ` [PATCH v4] " Kurt Manucredo
2021-06-05 17:55 ` Yonghong Song
2021-06-05 19:10 ` Alexei Starovoitov
2021-06-05 21:39 ` Yonghong Song
2021-06-06 19:44 ` Kurt Manucredo
2021-06-07 7:38 ` Dmitry Vyukov
2021-06-09 18:20 ` Kees Cook
2021-06-09 23:40 ` Yonghong Song
2021-06-10 5:32 ` Dmitry Vyukov
2021-06-10 6:06 ` Yonghong Song
2021-06-10 17:06 ` Kees Cook
2021-06-10 17:52 ` Alexei Starovoitov
2021-06-10 20:00 ` Eric Biggers
2021-06-15 16:42 ` [PATCH v5] " Kurt Manucredo
2021-06-15 18:51 ` Edward Cree
2021-06-15 19:33 ` Eric Biggers
2021-06-15 21:08 ` Daniel Borkmann
2021-06-15 21:32 ` Eric Biggers
2021-06-15 21:38 ` Eric Biggers
2021-06-15 21:54 ` Daniel Borkmann
2021-06-15 22:07 ` Eric Biggers
2021-06-15 22:31 ` Kurt Manucredo
2021-06-17 10:09 ` Daniel Borkmann
2021-06-06 19:15 ` [PATCH v4] " Kurt Manucredo
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