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authorJiong Wang <jiong.wang@netronome.com>2019-06-25 17:41:50 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2019-06-26 14:48:20 +0200
commit75672dda27bd00109a84cd975c17949ad9c45663 (patch)
treeb133c5796f60d4f2407d98ff14fcd59937605038 /kernel/bpf/core.c
parent6c6874f401e5a0caab3b6a0663169e1fb5e930bb (diff)
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 <yauheni.kaliuta@redhat.com> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel/bpf/core.c')
-rw-r--r--kernel/bpf/core.c4
1 files changed, 2 insertions, 2 deletions
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;