| Message ID | 1561480910-23543-1-git-send-email-jiong.wang@netronome.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf] bpf: fix BPF_ALU32 | BPF_ARSH on BE arches | expand |
On Tue, Jun 25, 2019 at 12:31 PM Jiong Wang <jiong.wang@netronome.com> wrote: > > 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> I guess we need: Cc: <stable@vger.kernel.org> #v5.0+ > --- > kernel/bpf/core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 080e2bb..f2148db 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -1364,10 +1364,10 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) > 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; > -- > 2.7.4 >
On 06/25/2019 06:41 PM, Jiong Wang wrote: > 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> Applied, thanks!
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 080e2bb..f2148db 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1364,10 +1364,10 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) 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;
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> --- kernel/bpf/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)