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arm64: bpf: fix endianness conversion bugs 

Upper bits should be zeroed in endianness conversion:

- even when there's no need to change endianness (i.e., BPF_FROM_BE
  on big endian or BPF_FROM_LE on little endian);

- after rev16.

This patch fixes such bugs by emitting extra instructions to clear
upper bits.

Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Fixes: e54bcde3d6 ("arm64: eBPF JIT compiler")
Cc: <stable@vger.kernel.org> # 3.18+
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Xi Wang 2015-06-25 18:39:15 -07:00 committed by Catalin Marinas
parent 8eee539dde
commit d63903bbc3
2 changed files with 24 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/net/bpf_jit.h
View File

@ -110,6 +110,10 @@
/* Rd = Rn >> shift; signed */
#define A64_ASR(sf, Rd, Rn, shift) A64_SBFM(sf, Rd, Rn, shift, (sf) ? 63 : 31)
/* Zero extend */
#define A64_UXTH(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 15)
#define A64_UXTW(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 31)
/* Move wide (immediate) */
#define A64_MOVEW(sf, Rd, imm16, shift, type) \
aarch64_insn_gen_movewide(Rd, imm16, shift, \

22
arch/arm64/net/bpf_jit_comp.c
View File

@ -289,23 +289,41 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
case BPF_ALU | BPF_END | BPF_FROM_BE:
#ifdef CONFIG_CPU_BIG_ENDIAN
if (BPF_SRC(code) == BPF_FROM_BE)
break;
goto emit_bswap_uxt;
#else /* !CONFIG_CPU_BIG_ENDIAN */
if (BPF_SRC(code) == BPF_FROM_LE)
break;
goto emit_bswap_uxt;
#endif
switch (imm) {
case 16:
emit(A64_REV16(is64, dst, dst), ctx);
/* zero-extend 16 bits into 64 bits */
emit(A64_UXTH(is64, dst, dst), ctx);
break;
case 32:
emit(A64_REV32(is64, dst, dst), ctx);
/* upper 32 bits already cleared */
break;
case 64:
emit(A64_REV64(dst, dst), ctx);
break;
}
break;
emit_bswap_uxt:
switch (imm) {
case 16:
/* zero-extend 16 bits into 64 bits */
emit(A64_UXTH(is64, dst, dst), ctx);
break;
case 32:
/* zero-extend 32 bits into 64 bits */
emit(A64_UXTW(is64, dst, dst), ctx);
break;
case 64:
/* nop */
break;
}
break;
/* dst = imm */
case BPF_ALU | BPF_MOV | BPF_K:
case BPF_ALU64 | BPF_MOV | BPF_K: