Merge branch 'fix-btf_dedup'

Alexei Starovoitov · Alexei Starovoitov · commit 369b976d6f36 · 2019-03-27T08:01:26.000-07:00
Andrii Nakryiko says:

====================
This patch set fixes bug in btf_dedup_is_equiv() check mishandling equivalence
comparison between VOID kind in candidate type graph versus anonymous non-VOID
kind in canonical type graph.

Patch #1 fixes bug, by comparing candidate and canonical kinds for equality,
before proceeding to kind-specific checks.
Patch #2 adds a test case testing this specific scenario.
====================

Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
@@ -2107,6 +2107,9 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 		return fwd_kind == real_kind;
 	}
 
+	if (cand_kind != canon_kind)
+		return 0;
+
 	switch (cand_kind) {
 	case BTF_KIND_INT:
 		return btf_equal_int(cand_type, canon_type);
diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
@@ -5776,6 +5776,53 @@ const struct btf_dedup_test dedup_tests[] = {
 		.dedup_table_size = 1, /* force hash collisions */
 	},
 },
+{
+	.descr = "dedup: void equiv check",
+	/*
+	 * // CU 1:
+	 * struct s {
+	 *	struct {} *x;
+	 * };
+	 * // CU 2:
+	 * struct s {
+	 *	int *x;
+	 * };
+	 */
+	.input = {
+		.raw_types = {
+			/* CU 1 */
+			BTF_STRUCT_ENC(0, 0, 1),				/* [1] struct {}  */
+			BTF_PTR_ENC(1),						/* [2] ptr -> [1] */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [3] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 2, 0),
+			/* CU 2 */
+			BTF_PTR_ENC(0),						/* [4] ptr -> void */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [5] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 4, 0),
+			BTF_END_RAW,
+		},
+		BTF_STR_SEC("\0s\0x"),
+	},
+	.expect = {
+		.raw_types = {
+			/* CU 1 */
+			BTF_STRUCT_ENC(0, 0, 1),				/* [1] struct {}  */
+			BTF_PTR_ENC(1),						/* [2] ptr -> [1] */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [3] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 2, 0),
+			/* CU 2 */
+			BTF_PTR_ENC(0),						/* [4] ptr -> void */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [5] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 4, 0),
+			BTF_END_RAW,
+		},
+		BTF_STR_SEC("\0s\0x"),
+	},
+	.opts = {
+		.dont_resolve_fwds = false,
+		.dedup_table_size = 1, /* force hash collisions */
+	},
+},
 {
 	.descr = "dedup: all possible kinds (no duplicates)",
 	.input = {

Original file line number	Diff line number	Diff line change
`@@ -2107,6 +2107,9 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,`
`2107`	`2107`	`return fwd_kind == real_kind;`
`2108`	`2108`	`}`
`2109`	`2109`
	`2110`	`+ if (cand_kind != canon_kind)`
	`2111`	`+ return 0;`
	`2112`	`+`
`2110`	`2113`	`switch (cand_kind) {`
`2111`	`2114`	`case BTF_KIND_INT:`
`2112`	`2115`	`return btf_equal_int(cand_type, canon_type);`