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authorRabin Vincent <rabin@rab.in>2016-01-05 16:23:07 +0100
committerDavid S. Miller <davem@davemloft.net>2016-01-06 00:43:52 -0500
commit55795ef5469290f89f04e12e662ded604909e462 (patch)
treedf413e913330af821e7989534a4d36ea621bab56 /arch/arm
parentff62198553e43cdffa9d539f6165d3e83f8a42bc (diff)
net: filter: make JITs zero A for SKF_AD_ALU_XOR_X
The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data instructions since it XORs A with X while all the others replace A with some loaded value. All the BPF JITs fail to clear A if this is used as the first instruction in a filter. This was found using american fuzzy lop. Add a helper to determine if A needs to be cleared given the first instruction in a filter, and use this in the JITs. Except for ARM, the rest have only been compile-tested. Fixes: 3480593131e0 ("net: filter: get rid of BPF_S_* enum") Signed-off-by: Rabin Vincent <rabin@rab.in> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/net/bpf_jit_32.c16
1 files changed, 1 insertions, 15 deletions
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 591f9db3bf40..e153eb065fe4 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -187,19 +187,6 @@ static inline int mem_words_used(struct jit_ctx *ctx)
return fls(ctx->seen & SEEN_MEM);
}
-static inline bool is_load_to_a(u16 inst)
-{
- switch (inst) {
- case BPF_LD | BPF_W | BPF_LEN:
- case BPF_LD | BPF_W | BPF_ABS:
- case BPF_LD | BPF_H | BPF_ABS:
- case BPF_LD | BPF_B | BPF_ABS:
- return true;
- default:
- return false;
- }
-}
-
static void jit_fill_hole(void *area, unsigned int size)
{
u32 *ptr;
@@ -211,7 +198,6 @@ static void jit_fill_hole(void *area, unsigned int size)
static void build_prologue(struct jit_ctx *ctx)
{
u16 reg_set = saved_regs(ctx);
- u16 first_inst = ctx->skf->insns[0].code;
u16 off;
#ifdef CONFIG_FRAME_POINTER
@@ -241,7 +227,7 @@ static void build_prologue(struct jit_ctx *ctx)
emit(ARM_MOV_I(r_X, 0), ctx);
/* do not leak kernel data to userspace */
- if ((first_inst != (BPF_RET | BPF_K)) && !(is_load_to_a(first_inst)))
+ if (bpf_needs_clear_a(&ctx->skf->insns[0]))
emit(ARM_MOV_I(r_A, 0), ctx);
/* stack space for the BPF_MEM words */