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From: Frank van der Linden <fllinden@amazon.com>
To: <stable@vger.kernel.org>
Cc: <bpf@vger.kernel.org>
Subject: [PATCH 5.4 6/8] bpf: Move sanitize_val_alu out of op switch
Date: Thu, 29 Apr 2021 22:08:37 +0000
Message-ID: <20210429220839.15667-7-fllinden@amazon.com> (raw)
In-Reply-To: <20210429220839.15667-1-fllinden@amazon.com>

From: Daniel Borkmann <daniel@iogearbox.net>

commit f528819334881fd622fdadeddb3f7edaed8b7c9b upstream.

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 5.4]
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 fc33aed59333..b8abdbb4c063 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4352,6 +4352,11 @@ 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,
@@ -4753,11 +4758,14 @@ 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;
@@ -4777,9 +4785,6 @@ 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 index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-29 22:08 [PATCH 5.4 0/8] BPF backports for CVE-2021-29155 Frank van der Linden
2021-04-29 22:08 ` [PATCH 5.4 1/8] bpf: Move off_reg into sanitize_ptr_alu Frank van der Linden
2021-04-29 22:08 ` [PATCH 5.4 2/8] bpf: Ensure off_reg has no mixed signed bounds for all types Frank van der Linden
2021-04-29 22:08 ` [PATCH 5.4 3/8] bpf: Rework ptr_limit into alu_limit and add common error path Frank van der Linden
2021-04-29 22:08 ` [PATCH 5.4 4/8] bpf: Improve verifier error messages for users Frank van der Linden
2021-04-29 22:08 ` [PATCH 5.4 5/8] bpf: Refactor and streamline bounds check into helper Frank van der Linden
2021-04-29 22:08 ` Frank van der Linden [this message]
2021-04-29 22:08 ` [PATCH 5.4 7/8] bpf: Tighten speculative pointer arithmetic mask Frank van der Linden
2021-04-29 22:08 ` [PATCH 5.4 8/8] bpf: Update selftests to reflect new error states Frank van der Linden
2021-04-30 13:38 ` [PATCH 5.4 0/8] BPF backports for CVE-2021-29155 Greg KH
2021-04-30 16:38   ` van der Linden, Frank
2021-05-01  6:05     ` Greg KH
2021-05-01 17:54       ` van der Linden, Frank
     [not found] <20210430141911.137473863@linuxfoundation.org>
2021-04-30 14:20 ` [PATCH 5.4 6/8] bpf: Move sanitize_val_alu out of op switch Greg Kroah-Hartman

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