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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 09/15] bpf: Move sanitize_val_alu out of op switch
Date: Sat, 1 May 2021 04:30:08 +0000	[thread overview]
Message-ID: <20210501043014.33300-10-fllinden@amazon.com> (raw)
In-Reply-To: <20210501043014.33300-1-fllinden@amazon.com>

From: Daniel Borkmann <daniel@iogearbox.net>

Upstream commit f528819334881fd622fdadeddb3f7edaed8b7c9b

Add a small sanitize_needed() helper function and move sanitize_val_alu()
out of the main opcode switch. In upcoming work, we'll move sanitize_ptr_alu()
as well out of its opcode switch so this helps to streamline both.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
[fllinden@amazon.com: backported to 4.14]
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
---
 kernel/bpf/verifier.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 55ac2ab5eabc..db6b08058c19 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2110,6 +2110,11 @@ static int sanitize_val_alu(struct bpf_verifier_env *env,
 	return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
 }
 
+static bool sanitize_needed(u8 opcode)
+{
+	return opcode == BPF_ADD || opcode == BPF_SUB;
+}
+
 static int sanitize_ptr_alu(struct bpf_verifier_env *env,
 			    struct bpf_insn *insn,
 			    const struct bpf_reg_state *ptr_reg,
@@ -2510,11 +2515,14 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
 		return 0;
 	}
 
-	switch (opcode) {
-	case BPF_ADD:
+	if (sanitize_needed(opcode)) {
 		ret = sanitize_val_alu(env, insn);
 		if (ret < 0)
 			return sanitize_err(env, insn, ret, NULL, NULL);
+	}
+
+	switch (opcode) {
+	case BPF_ADD:
 		if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
 		    signed_add_overflows(dst_reg->smax_value, smax_val)) {
 			dst_reg->smin_value = S64_MIN;
@@ -2534,9 +2542,6 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
 		dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
 		break;
 	case BPF_SUB:
-		ret = sanitize_val_alu(env, insn);
-		if (ret < 0)
-			return sanitize_err(env, insn, ret, NULL, NULL);
 		if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
 		    signed_sub_overflows(dst_reg->smax_value, smin_val)) {
 			/* Overflow possible, we know nothing */
-- 
2.23.3


  parent reply	other threads:[~2021-05-01  4:31 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 ` Frank van der Linden [this message]
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 ` [PATCH 4.14 13/15] bpf/verifier: disallow pointer subtraction Frank van der Linden
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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