From 75672dda27bd00109a84cd975c17949ad9c45663 Mon Sep 17 00:00:00 2001 From: Jiong Wang Date: Tue, 25 Jun 2019 17:41:50 +0100 Subject: bpf: fix BPF_ALU32 | BPF_ARSH on BE arches Yauheni reported the following code do not work correctly on BE arches: ALU_ARSH_X: DST = (u64) (u32) ((*(s32 *) &DST) >> SRC); CONT; ALU_ARSH_K: DST = (u64) (u32) ((*(s32 *) &DST) >> IMM); CONT; and are causing failure of test_verifier test 'arsh32 on imm 2' on BE arches. The code is taking address and interpreting memory directly, so is not endianness neutral. We should instead perform standard C type casting on the variable. A u64 to s32 conversion will drop the high 32-bit and reserve the low 32-bit as signed integer, this is all we want. Fixes: 2dc6b100f928 ("bpf: interpreter support BPF_ALU | BPF_ARSH") Reported-by: Yauheni Kaliuta Reviewed-by: Jakub Kicinski Reviewed-by: Quentin Monnet Signed-off-by: Jiong Wang Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/bpf/core.c') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 080e2bb644cc..f2148db91439 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1364,10 +1364,10 @@ select_insn: insn++; CONT; ALU_ARSH_X: - DST = (u64) (u32) ((*(s32 *) &DST) >> SRC); + DST = (u64) (u32) (((s32) DST) >> SRC); CONT; ALU_ARSH_K: - DST = (u64) (u32) ((*(s32 *) &DST) >> IMM); + DST = (u64) (u32) (((s32) DST) >> IMM); CONT; ALU64_ARSH_X: (*(s64 *) &DST) >>= SRC; -- cgit v1.2.3-59-g8ed1b