From: Alexei Starovoitov <ast@kernel.org>
Date: Mon, 1 Nov 2021 22:21:52 +0000 (-0700)
Subject: bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
X-Git-Tag: v5.14.19~314
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8426a23213dc6519282372eba0cc1b3099b1b03d;p=thirdparty%2Fkernel%2Fstable.git

bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.

[ Upstream commit 388e2c0b978339dee9b0a81a2e546f8979e021e2 ]

Similar to unsigned bounds propagation fix signed bounds.
The 'Fixes' tag is a hint. There is no security bug here.
The verifier was too conservative.

Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-2-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b9fb079559a6d..4dd9cedfc453d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1397,7 +1397,7 @@ static void __reg_combine_32_into_64(struct bpf_reg_state *reg)
 
 static bool __reg64_bound_s32(s64 a)
 {
-	return a > S32_MIN && a < S32_MAX;
+	return a >= S32_MIN && a <= S32_MAX;
 }
 
 static bool __reg64_bound_u32(u64 a)