From: Alexei Starovoitov <a...@plumgrid.com>
commit 83d5b7ef99c9f05e87333b334a638de1264ab8e4 upstream
exisiting BPF verifier allows uninitialized access to registers,
'ret A' is considered to be a valid filter.
So initialize A and X to zero to prevent leaking kernel memory
In the future BPF verifier will be rejecting such filters
Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
Cc: Daniel Borkmann <dbork...@redhat.com>
Acked-by: Daniel Borkmann <dbork...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: He Zhe <zhe...@windriver.com>
---
net/core/filter.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index cd58614..9d79ca0 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -122,6 +122,13 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64
r4, u64 r5)
return 0;
}
+/* Register mappings for user programs. */
+#define A_REG 0
+#define X_REG 7
+#define TMP_REG 8
+#define ARG2_REG 2
+#define ARG3_REG 3
+
/**
* __sk_run_filter - run a filter on a given context
* @ctx: buffer to run the filter on
@@ -242,6 +249,8 @@ unsigned int __sk_run_filter(void *ctx, const struct
sock_filter_int *insn)
regs[FP_REG] = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)];
regs[ARG1_REG] = (u64) (unsigned long) ctx;
+ regs[A_REG] = 0;
+ regs[X_REG] = 0;
select_insn:
goto *jumptable[insn->code];
@@ -643,19 +652,12 @@ static u64 __get_raw_cpu_id(u64 ctx, u64 A, u64 X, u64
r4, u64 r5)
return raw_smp_processor_id();
}
/* note that this only generates 32-bit random numbers */
static u64 __get_random_u32(u64 ctx, u64 A, u64 X, u64 r4, u64 r5)
{
return (u64)prandom_u32();
}
-/* Register mappings for user programs. */
-#define A_REG 0
-#define X_REG 7
-#define TMP_REG 8
-#define ARG2_REG 2
-#define ARG3_REG 3
-
static bool convert_bpf_extensions(struct sock_filter *fp,
struct sock_filter_int **insnp)
{
--
1.9.1
--
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