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From: Kurt Manucredo <fuzzybritches0@gmail.com>
To: gregkh@linuxfoundation.org
Cc: linux-kernel-mentees@lists.linuxfoundation.org
Subject: [PATCH] bpf: core: fix shift-out-of-bounds in ___bpf_prog_run
Date: Wed, 26 May 2021 23:40:27 +0200	[thread overview]
Message-ID: <60aec085.1c69fb81.972cc.0bfb@mx.google.com> (raw)

Fix shift-out-of-bounds in ___bpf_prog_run().

UBSAN: shift-out-of-bounds in kernel/bpf/core.c:1414:2
shift exponent 248 is too large for 32-bit type 'unsigned int'
https://syzkaller.appspot.com/bug?id=edb51be4c9a320186328893287bb30d5eed09231

Reported-by: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com
Signed-off-by: Kurt Manucredo <fuzzybritches0@gmail.com>
---
 kernel/bpf/core.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 5e31ee9f7512..35cba247c531 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1411,11 +1411,38 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
 	ALU(SUB,  -)
 	ALU(AND,  &)
 	ALU(OR,   |)
-	ALU(LSH, <<)
-	ALU(RSH, >>)
 	ALU(XOR,  ^)
 	ALU(MUL,  *)
 #undef ALU
+#define ALU(OPCODE, OP)		\
+	ALU64_##OPCODE##_X:		\
+		if (SRC >= 64)		\
+			DST = 0;	\
+		else			\
+			DST = DST OP SRC;	\
+		CONT;			\
+	ALU_##OPCODE##_X:		\
+		if (SRC >= 32)		\
+			DST = 0;	\
+		else			\
+			DST = (u32) DST OP (u32) SRC;	\
+		CONT;			\
+	ALU64_##OPCODE##_K:		\
+		if (IMM >= 64)		\
+			DST = 0;	\
+		else			\
+			DST = DST OP IMM;	\
+		CONT;			\
+	ALU_##OPCODE##_K:		\
+		if (IMM >= 32)		\
+			DST = 0;	\
+		else			\
+			DST = (u32) DST OP (u32) IMM;	\
+		CONT;
+
+	ALU(LSH, <<)
+	ALU(RSH, >>)
+#undef ALU
 	ALU_NEG:
 		DST = (u32) -DST;
 		CONT;
-- 
2.30.2

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             reply	other threads:[~2021-05-26 21:41 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-26 21:40 Kurt Manucredo [this message]
2021-05-27  4:29 ` [PATCH] bpf: core: fix shift-out-of-bounds in ___bpf_prog_run Greg KH
2021-06-01 14:33   ` [PATCH v2] " Kurt Manucredo
2021-06-01 15:43     ` Greg KH
2021-06-01 21:28       ` Kurt Manucredo
2021-06-02  6:09         ` Greg KH
2021-06-02  6:36           ` Pavel Skripkin
2021-06-04 21:15             ` Kurt Manucredo

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