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authorAlexei Starovoitov <ast@kernel.org>2018-01-23 20:05:51 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2018-01-24 10:39:58 +0100
commit31e95b61e172144bb2b626a291db1bdc0769275b (patch)
treef64c8ada251c8120e8c8e40daa5b90d77be43228 /tools
parent783687810e986a15ffbf86c516a1a48ff37f38f7 (diff)
downloadlinux-31e95b61e172144bb2b626a291db1bdc0769275b.tar.bz2
selftests/bpf: make 'dubious pointer arithmetic' test useful
mostly revert the previous workaround and make 'dubious pointer arithmetic' test useful again. Use (ptr - ptr) << const instead of ptr << const to generate large scalar. The rest stays as before commit 2b36047e7889. Fixes: 2b36047e7889 ("selftests/bpf: fix test_align") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/test_align.c30
1 files changed, 23 insertions, 7 deletions
diff --git a/tools/testing/selftests/bpf/test_align.c b/tools/testing/selftests/bpf/test_align.c
index e19b410125eb..ff8bd7e3e50c 100644
--- a/tools/testing/selftests/bpf/test_align.c
+++ b/tools/testing/selftests/bpf/test_align.c
@@ -446,11 +446,9 @@ static struct bpf_align_test tests[] = {
.insns = {
PREP_PKT_POINTERS,
BPF_MOV64_IMM(BPF_REG_0, 0),
- /* ptr & const => unknown & const */
- BPF_MOV64_REG(BPF_REG_5, BPF_REG_2),
- BPF_ALU64_IMM(BPF_AND, BPF_REG_5, 0x40),
- /* ptr << const => unknown << const */
- BPF_MOV64_REG(BPF_REG_5, BPF_REG_2),
+ /* (ptr - ptr) << 2 */
+ BPF_MOV64_REG(BPF_REG_5, BPF_REG_3),
+ BPF_ALU64_REG(BPF_SUB, BPF_REG_5, BPF_REG_2),
BPF_ALU64_IMM(BPF_LSH, BPF_REG_5, 2),
/* We have a (4n) value. Let's make a packet offset
* out of it. First add 14, to make it a (4n+2)
@@ -473,8 +471,26 @@ static struct bpf_align_test tests[] = {
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
.result = REJECT,
.matches = {
- {4, "R5_w=pkt(id=0,off=0,r=0,imm=0)"},
- /* R5 bitwise operator &= on pointer prohibited */
+ {4, "R5_w=pkt_end(id=0,off=0,imm=0)"},
+ /* (ptr - ptr) << 2 == unknown, (4n) */
+ {6, "R5_w=inv(id=0,smax_value=9223372036854775804,umax_value=18446744073709551612,var_off=(0x0; 0xfffffffffffffffc))"},
+ /* (4n) + 14 == (4n+2). We blow our bounds, because
+ * the add could overflow.
+ */
+ {7, "R5=inv(id=0,var_off=(0x2; 0xfffffffffffffffc))"},
+ /* Checked s>=0 */
+ {9, "R5=inv(id=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
+ /* packet pointer + nonnegative (4n+2) */
+ {11, "R6_w=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
+ {13, "R4=pkt(id=1,off=4,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
+ /* NET_IP_ALIGN + (4n+2) == (4n), alignment is fine.
+ * We checked the bounds, but it might have been able
+ * to overflow if the packet pointer started in the
+ * upper half of the address space.
+ * So we did not get a 'range' on R6, and the access
+ * attempt will fail.
+ */
+ {15, "R6=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
}
},
{