[PATCH] bpf: core: fix shift-out-of-bounds in ___bpf_prog_run
Kurt Manucredo
fuzzybritches0 at gmail.com
Wed May 26 21:40:27 UTC 2021
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 at syzkaller.appspotmail.com
Signed-off-by: Kurt Manucredo <fuzzybritches0 at 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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