From: Frank van der Linden <fllinden@amazon.com>
To: <stable@vger.kernel.org>
Cc: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
<yhs@fb.com>, <john.fastabend@gmail.com>, <samjonas@amazon.com>
Subject: [PATCH 4.14 13/15] bpf/verifier: disallow pointer subtraction
Date: Sat, 1 May 2021 04:30:12 +0000 [thread overview]
Message-ID: <20210501043014.33300-14-fllinden@amazon.com> (raw)
In-Reply-To: <20210501043014.33300-1-fllinden@amazon.com>
From: Alexei Starovoitov <ast@kernel.org>
Upstream commit dd066823db2ac4e22f721ec85190817b58059a54
Subtraction of pointers was accidentally allowed for unpriv programs
by commit 82abbf8d2fc4. Revert that part of commit.
Fixes: 82abbf8d2fc4 ("bpf: do not allow root to mangle valid pointers")
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
[fllinden@amazon.com: backport to 4.14]
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
---
kernel/bpf/verifier.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8ef1c74eaa11..abf85414c8d1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2754,7 +2754,7 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
* an arbitrary scalar. Disallow all math except
* pointer subtraction
*/
- if (opcode == BPF_SUB){
+ if (opcode == BPF_SUB && env->allow_ptr_leaks) {
mark_reg_unknown(regs, insn->dst_reg);
return 0;
}
--
2.23.3
next prev parent reply other threads:[~2021-05-01 4:30 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 4:29 [PATCH 4.14 00/15] fix backports, add CVE-2021-29155 fixes Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 01/15] bpf: Fix backport of "bpf: restrict unknown scalars of mixed signed bounds for unprivileged" Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 02/15] bpf: fix up selftests after backports were fixed Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 03/15] bpf, selftests: Fix up some test_verifier cases for unprivileged Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 04/15] bpf: Move off_reg into sanitize_ptr_alu Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 05/15] bpf: Ensure off_reg has no mixed signed bounds for all types Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 06/15] bpf: Rework ptr_limit into alu_limit and add common error path Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 07/15] bpf: Improve verifier error messages for users Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 08/15] bpf: Refactor and streamline bounds check into helper Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 09/15] bpf: Move sanitize_val_alu out of op switch Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 10/15] bpf: Tighten speculative pointer arithmetic mask Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 11/15] bpf: Update selftests to reflect new error states Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 12/15] bpf: do not allow root to mangle valid pointers Frank van der Linden
2021-05-01 4:30 ` Frank van der Linden [this message]
2021-05-01 4:30 ` [PATCH 4.14 14/15] selftests/bpf: fix test_align Frank van der Linden
2021-05-01 4:30 ` [PATCH 4.14 15/15] selftests/bpf: make 'dubious pointer arithmetic' test useful Frank van der Linden
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