selftests/bpf: Fix freplace_link segfault in tailcalls prog test

[ Upstream commit a63a631c9b5cb25a1c17dd2cb18c63df91e978b1 ]

There are two bpf_link__destroy(freplace_link) calls in
test_tailcall_bpf2bpf_freplace(). After the first bpf_link__destroy()
is called, if the following bpf_map_{update,delete}_elem() throws an
exception, it will jump to the "out" label and call bpf_link__destroy()
again, causing double free and eventually leading to a segfault.

Fix it by directly resetting freplace_link to NULL after the first
bpf_link__destroy() call.

Fixes: 021611d33e78 ("selftests/bpf: Add test to verify tailcall and freplace restrictions")
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/bpf/20250122022838.1079157-1-wutengda@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

This commit is contained in:

Tengda Wu

2025-01-22 10:28:38 +08:00

committed by

Greg Kroah-Hartman

parent 25aa4fe297

commit dcb5997ead

1 changed files with 1 additions and 0 deletions

									
										tools/testing/selftests/bpf/prog_tests/tailcalls.c
									
		+1
		
												View File
												
				@@ -1599,6 +1599,7 @@ static void test_tailcall_bpf2bpf_freplace(void)

						goto out;

					err = bpf_link__destroy(freplace_link);

					freplace_link = NULL;

					if (!ASSERT_OK(err, "destroy link"))

						goto out;