From 04e19012efaec2bfd8c3b37fd8a6c3f1fe731ffc Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sun, 19 Jul 2026 17:36:28 +0200 Subject: bpf: Fix offset warn check for bpf_res_spin_lock Sashiko pointed out correctly that the case statement for BPF_RES_SPIN_LOCK incorrectly checks offset for BPF_SPIN_LOCK. Fix it by checking res_spin_lock_off instead. Fixes: 0de2046137f9 ("bpf: Implement verifier support for rqspinlock") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://patch.msgid.link/20260719153634.2908692-2-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index cbb1e49b9bcb..e7d4e9ba24e2 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4168,7 +4168,7 @@ struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type rec->spin_lock_off = rec->fields[i].offset; break; case BPF_RES_SPIN_LOCK: - WARN_ON_ONCE(rec->spin_lock_off >= 0); + WARN_ON_ONCE(rec->res_spin_lock_off >= 0); /* Cache offset for faster lookup at runtime */ rec->res_spin_lock_off = rec->fields[i].offset; break; -- cgit v1.2.3 From f08619f060468076e4acbdc10e0713af20d60e65 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sun, 19 Jul 2026 17:36:29 +0200 Subject: bpf: Preserve unique-field state across nested structs btf_find_struct_field() initializes a fresh seen mask for every recursive descent. Unique special fields in different levels of the same aggregate therefore do not see one another. The duplicate fields can reach btf_parse_fields(), where they trigger an invariant WARN_ON_ONCE(). A crafted user BTF can consequently trigger the warning before map creation checks capabilities. Initialize the seen mask once in btf_find_field() and pass the same pointer through struct, datasec, and nested-struct walks. This gives the entire field traversal one shared uniqueness state. Fixes: 64e8ee814819 ("bpf: look into the types of the fields of a struct type recursively.") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://patch.msgid.link/20260719153634.2908692-3-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/btf.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e7d4e9ba24e2..c577f00e9d88 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3751,7 +3751,7 @@ static int btf_repeat_fields(struct btf_field_info *info, int info_cnt, static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t, u32 field_mask, struct btf_field_info *info, int info_cnt, - u32 level); + u32 level, u32 *seen_mask); /* Find special fields in the struct type of a field. * @@ -3762,7 +3762,7 @@ static int btf_find_struct_field(const struct btf *btf, static int btf_find_nested_struct(const struct btf *btf, const struct btf_type *t, u32 off, u32 nelems, u32 field_mask, struct btf_field_info *info, - int info_cnt, u32 level) + int info_cnt, u32 level, u32 *seen_mask) { int ret, err, i; @@ -3770,7 +3770,7 @@ static int btf_find_nested_struct(const struct btf *btf, const struct btf_type * if (level >= MAX_RESOLVE_DEPTH) return -E2BIG; - ret = btf_find_struct_field(btf, t, field_mask, info, info_cnt, level); + ret = btf_find_struct_field(btf, t, field_mask, info, info_cnt, level, seen_mask); if (ret <= 0) return ret; @@ -3827,7 +3827,7 @@ static int btf_find_field_one(const struct btf *btf, if (expected_size && expected_size != sz * nelems) return 0; ret = btf_find_nested_struct(btf, var_type, off, nelems, field_mask, - &info[0], info_cnt, level); + &info[0], info_cnt, level, seen_mask); return ret; } @@ -3892,11 +3892,11 @@ static int btf_find_field_one(const struct btf *btf, static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t, u32 field_mask, struct btf_field_info *info, int info_cnt, - u32 level) + u32 level, u32 *seen_mask) { int ret, idx = 0; const struct btf_member *member; - u32 i, off, seen_mask = 0; + u32 i, off; for_each_member(i, t, member) { const struct btf_type *member_type = btf_type_by_id(btf, @@ -3910,7 +3910,7 @@ static int btf_find_struct_field(const struct btf *btf, ret = btf_find_field_one(btf, t, member_type, i, off, 0, - field_mask, &seen_mask, + field_mask, seen_mask, &info[idx], info_cnt - idx, level); if (ret < 0) return ret; @@ -3921,11 +3921,11 @@ static int btf_find_struct_field(const struct btf *btf, static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t, u32 field_mask, struct btf_field_info *info, - int info_cnt, u32 level) + int info_cnt, u32 level, u32 *seen_mask) { int ret, idx = 0; const struct btf_var_secinfo *vsi; - u32 i, off, seen_mask = 0; + u32 i, off; for_each_vsi(i, t, vsi) { const struct btf_type *var = btf_type_by_id(btf, vsi->type); @@ -3933,7 +3933,7 @@ static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t, off = vsi->offset; ret = btf_find_field_one(btf, var, var_type, -1, off, vsi->size, - field_mask, &seen_mask, + field_mask, seen_mask, &info[idx], info_cnt - idx, level); if (ret < 0) @@ -3947,10 +3947,12 @@ static int btf_find_field(const struct btf *btf, const struct btf_type *t, u32 field_mask, struct btf_field_info *info, int info_cnt) { + u32 seen_mask = 0; + if (__btf_type_is_struct(t)) - return btf_find_struct_field(btf, t, field_mask, info, info_cnt, 0); + return btf_find_struct_field(btf, t, field_mask, info, info_cnt, 0, &seen_mask); else if (btf_type_is_datasec(t)) - return btf_find_datasec_var(btf, t, field_mask, info, info_cnt, 0); + return btf_find_datasec_var(btf, t, field_mask, info, info_cnt, 0, &seen_mask); return -EINVAL; } -- cgit v1.2.3 From 61e655391cb19c31f94ecd4354f624c81ce4cf75 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sun, 19 Jul 2026 17:36:30 +0200 Subject: bpf: Mark bpf_refcount field as unique BPF_REFCOUNT is not marked as a unique field, while it should be. Fix this oversight. Fixes: d54730b50bae ("bpf: Introduce opaque bpf_refcount struct and add btf_record plumbing") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://patch.msgid.link/20260719153634.2908692-4-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index c577f00e9d88..4eeeaeb69790 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3669,7 +3669,7 @@ static int btf_get_field_type(const struct btf *btf, const struct btf_type *var_ { BPF_LIST_NODE, "bpf_list_node", false }, { BPF_RB_ROOT, "bpf_rb_root", false }, { BPF_RB_NODE, "bpf_rb_node", false }, - { BPF_REFCOUNT, "bpf_refcount", false }, + { BPF_REFCOUNT, "bpf_refcount", true }, }; int type = 0, i; const char *name = __btf_name_by_offset(btf, var_type->name_off); -- cgit v1.2.3 From 9f2afb635cffd670e71580a3070b6e5c68fb99c5 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sun, 19 Jul 2026 17:36:31 +0200 Subject: selftests/bpf: Test duplicate unique fields in nested structs Add a raw BTF test with a spin lock directly in a struct and another in a nested struct. The duplicate must now be rejected during BTF loading. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://patch.msgid.link/20260719153634.2908692-5-memxor@gmail.com Signed-off-by: Eduard Zingerman --- tools/testing/selftests/bpf/prog_tests/btf.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c index 66855cbd6b73..2100400d896b 100644 --- a/tools/testing/selftests/bpf/prog_tests/btf.c +++ b/tools/testing/selftests/bpf/prog_tests/btf.c @@ -4250,6 +4250,33 @@ static struct btf_raw_test raw_tests[] = { .max_entries = 1, }, +/* + * struct inner { + * struct bpf_spin_lock lock; + * }; + * + * struct value { + * struct bpf_spin_lock lock; + * struct inner nested; + * }; + */ +{ + .descr = "struct test duplicate nested unique fields", + .raw_types = { + BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + BTF_STRUCT_ENC(NAME_TBD, 1, 4), /* [2] */ + BTF_MEMBER_ENC(NAME_TBD, 1, 0), + BTF_STRUCT_ENC(NAME_TBD, 1, 4), /* [3] */ + BTF_MEMBER_ENC(NAME_TBD, 2, 0), + BTF_STRUCT_ENC(NAME_TBD, 2, 8), /* [4] */ + BTF_MEMBER_ENC(NAME_TBD, 2, 0), + BTF_MEMBER_ENC(NAME_TBD, 3, 32), + BTF_END_RAW, + }, + BTF_STR_SEC("\0int\0bpf_spin_lock\0val\0inner\0lock\0value\0lock\0nested"), + .btf_load_err = true, +}, + { .descr = "struct test repeated fields count overflow", .raw_types = { -- cgit v1.2.3 From 643bd5af853f41cc16e8d0d2e0ae12d60844402d Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sun, 19 Jul 2026 17:36:32 +0200 Subject: selftests/bpf: Test duplicate bpf_refcount fields Add a raw BTF test with two bpf_refcount fields. The duplicate must be rejected during BTF loading instead of reaching the duplicate-field invariant in btf_parse_fields(). Signed-off-by: Kumar Kartikeya Dwivedi Link: https://patch.msgid.link/20260719153634.2908692-6-memxor@gmail.com Signed-off-by: Eduard Zingerman --- tools/testing/selftests/bpf/prog_tests/btf.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c index 2100400d896b..67b9015cbd98 100644 --- a/tools/testing/selftests/bpf/prog_tests/btf.c +++ b/tools/testing/selftests/bpf/prog_tests/btf.c @@ -4277,6 +4277,27 @@ static struct btf_raw_test raw_tests[] = { .btf_load_err = true, }, +/* + * struct value { + * struct bpf_refcount a; + * struct bpf_refcount b; + * }; + */ +{ + .descr = "struct test duplicate bpf_refcount fields", + .raw_types = { + BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + BTF_STRUCT_ENC(NAME_TBD, 1, 4), /* [2] */ + BTF_MEMBER_ENC(NAME_TBD, 1, 0), + BTF_STRUCT_ENC(NAME_TBD, 2, 8), /* [3] */ + BTF_MEMBER_ENC(NAME_TBD, 2, 0), + BTF_MEMBER_ENC(NAME_TBD, 2, 32), + BTF_END_RAW, + }, + BTF_STR_SEC("\0int\0bpf_refcount\0refs\0value\0a\0b"), + .btf_load_err = true, +}, + { .descr = "struct test repeated fields count overflow", .raw_types = { -- cgit v1.2.3