Remove BUG_ON() if the shift immediate is >=32 to avoid
kernel crashes due to malicious user input. Since the micro-assembler
will not allow an immediate greater or equal to 32, we will use the
maximum value which is 31. This will do the correct thing on either 32-
or 64-bit cores since no 64-bit instructions are being used in JIT.
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Daniel Borkmann <dborkman@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
---
arch/mips/net/bpf_jit.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 1bcd599d9971..09ebc886c7aa 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -309,7 +309,8 @@ static inline void emit_sll(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
/* sa is 5-bits long */
- BUG_ON(sa >= BIT(5));
+ if (sa >= BIT(5))
+ sa = BIT(5) - 1;
emit_instr(ctx, sll, dst, src, sa);
}
@@ -323,7 +324,8 @@ static inline void emit_srl(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
/* sa is 5-bits long */
- BUG_ON(sa >= BIT(5));
+ if (sa >= BIT(5))
+ sa = BIT(5) - 1;
emit_instr(ctx, srl, dst, src, sa);
}
--
2.0.0
