6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kumar Kartikeya Dwivedi memxor@gmail.com
[ Upstream commit da1055b673f3baac2249571c9882ce767a0aa746 ]
The linked list failure test 'pop_front_off' and 'pop_back_off' currently rely on matching exact instruction and register values. The purpose of the test is to ensure the offset is correctly incremented for the returned pointers from list pop helpers, which can then be used with container_of to obtain the real object. Hence, somehow obtaining the information that the offset is 48 will work for us. Make the test more robust by relying on verifier error string of bpf_spin_lock and remove dependence on fragile instruction index or register number, which can be affected by different clang versions used to build the selftests.
Fixes: 300f19dcdb99 ("selftests/bpf: Add BPF linked list API tests") Reported-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Kumar Kartikeya Dwivedi memxor@gmail.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20231020144839.2734006-1-memxor@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/bpf/prog_tests/linked_list.c | 10 ++-------- tools/testing/selftests/bpf/progs/linked_list_fail.c | 4 +++- 2 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/linked_list.c b/tools/testing/selftests/bpf/prog_tests/linked_list.c index 18cf7b17463d9..98dde091d2825 100644 --- a/tools/testing/selftests/bpf/prog_tests/linked_list.c +++ b/tools/testing/selftests/bpf/prog_tests/linked_list.c @@ -94,14 +94,8 @@ static struct { { "incorrect_head_var_off2", "variable ptr_ access var_off=(0x0; 0xffffffff) disallowed" }, { "incorrect_head_off1", "bpf_list_head not found at offset=25" }, { "incorrect_head_off2", "bpf_list_head not found at offset=1" }, - { "pop_front_off", - "15: (bf) r1 = r6 ; R1_w=ptr_or_null_foo(id=4,ref_obj_id=4,off=48,imm=0) " - "R6_w=ptr_or_null_foo(id=4,ref_obj_id=4,off=48,imm=0) refs=2,4\n" - "16: (85) call bpf_this_cpu_ptr#154\nR1 type=ptr_or_null_ expected=percpu_ptr_" }, - { "pop_back_off", - "15: (bf) r1 = r6 ; R1_w=ptr_or_null_foo(id=4,ref_obj_id=4,off=48,imm=0) " - "R6_w=ptr_or_null_foo(id=4,ref_obj_id=4,off=48,imm=0) refs=2,4\n" - "16: (85) call bpf_this_cpu_ptr#154\nR1 type=ptr_or_null_ expected=percpu_ptr_" }, + { "pop_front_off", "off 48 doesn't point to 'struct bpf_spin_lock' that is at 40" }, + { "pop_back_off", "off 48 doesn't point to 'struct bpf_spin_lock' that is at 40" }, };
static void test_linked_list_fail_prog(const char *prog_name, const char *err_msg) diff --git a/tools/testing/selftests/bpf/progs/linked_list_fail.c b/tools/testing/selftests/bpf/progs/linked_list_fail.c index f4c63daba2297..6438982b928bd 100644 --- a/tools/testing/selftests/bpf/progs/linked_list_fail.c +++ b/tools/testing/selftests/bpf/progs/linked_list_fail.c @@ -591,7 +591,9 @@ int pop_ptr_off(void *(*op)(void *head)) n = op(&p->head); bpf_spin_unlock(&p->lock);
- bpf_this_cpu_ptr(n); + if (!n) + return 0; + bpf_spin_lock((void *)n); return 0; }