Commit 73278fd5 authored Aug 12, 2024 by Yonghong Song Committed by Wen Zhiwei Oct 12, 2024

selftests/bpf: Add a test to verify previous stacksafe() fix

stable inclusion
from stable-v6.6.48
commit b12caa8f08883558fcda5211d5034e3de05886e3
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAWEBV

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b12caa8f08883558fcda5211d5034e3de05886e3



--------------------------------

commit 662c3e2db00f92e50c26e9dc4fe47c52223d9982 upstream.

A selftest is added such that without the previous patch,
a crash can happen. With the previous patch, the test can
run successfully. The new test is written in a way which
mimics original crash case:
  main_prog
    static_prog_1
      static_prog_2
where static_prog_1 has different paths to static_prog_2
and some path has stack allocated and some other path
does not. A stacksafe() checking in static_prog_2()
triggered the crash.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240812214852.214037-1-yonghong.song@linux.dev


Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Wen Zhiwei <wenzhiwei@kylinos.cn>

parent 483adc64

tools/testing/selftests/bpf/progs/iters.c

+54 −0

Original line number	Diff line number	Diff line
		@@ -1411,4 +1411,58 @@ __naked int checkpoint_states_deletion(void)
		);
		}

		__u32 upper, select_n, result;
		__u64 global;

		static __noinline bool nest_2(char *str)
		{
		/* some insns (including branch insns) to ensure stacksafe() is triggered
		* in nest_2(). This way, stacksafe() can compare frame associated with nest_1().
		*/
		if (str[0] == 't')
		return true;
		if (str[1] == 'e')
		return true;
		if (str[2] == 's')
		return true;
		if (str[3] == 't')
		return true;
		return false;
		}

		static __noinline bool nest_1(int n)
		{
		/* case 0: allocate stack, case 1: no allocate stack */
		switch (n) {
		case 0: {
		char comm[16];

		if (bpf_get_current_comm(comm, 16))
		return false;
		return nest_2(comm);
		}
		case 1:
		return nest_2((char *)&global);
		default:
		return false;
		}
		}

		SEC("raw_tp")
		__success
		int iter_subprog_check_stacksafe(const void *ctx)
		{
		long i;

		bpf_for(i, 0, upper) {
		if (!nest_1(select_n)) {
		result = 1;
		return 0;
		}
		}

		result = 2;
		return 0;
		}

		char _license[] SEC("license") = "GPL";