Commit 6c4dedb7 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
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selftests/bpf: Prevent misaligned memory access in get_stack_raw_tp test 



Perfbuf doesn't guarantee 8-byte alignment of the data like BPF ringbuf
does, so struct get_stack_trace_t can arrive not properly aligned for
subsequent u64 accesses. Easiest fix is to just copy data locally.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-10-andrii@kernel.org
parent 3bd0233f

tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c

+10 −4
Original line number Diff line number Diff line
@@ -24,13 +24,19 @@ static void get_stack_print_output(void *ctx, int cpu, void *data, __u32 size) 
{

	bool good_kern_stack = false, good_user_stack = false;

	const char *nonjit_func = "___bpf_prog_run";

	struct get_stack_trace_t *e = data;

	/* perfbuf-submitted data is 4-byte aligned, but we need 8-byte

	 * alignment, so copy data into a local variable, for simplicity

	 */

	struct get_stack_trace_t e;

	int i, num_stack;

	static __u64 cnt;

	struct ksym *ks;



	cnt++;



	memset(&e, 0, sizeof(e));

	memcpy(&e, data, size <= sizeof(e) ? size : sizeof(e));



	if (size < sizeof(struct get_stack_trace_t)) {

		__u64 *raw_data = data;

		bool found = false;
@@ -57,19 +63,19 @@ static void get_stack_print_output(void *ctx, int cpu, void *data, __u32 size) 
			good_user_stack = true;

		}

	} else {

		num_stack = e->kern_stack_size / sizeof(__u64);

		num_stack = e.kern_stack_size / sizeof(__u64);

		if (env.jit_enabled) {

			good_kern_stack = num_stack > 0;

		} else {

			for (i = 0; i < num_stack; i++) {

				ks = ksym_search(e->kern_stack[i]);

				ks = ksym_search(e.kern_stack[i]);

				if (ks && (strcmp(ks->name, nonjit_func) == 0)) {

					good_kern_stack = true;

					break;

				}

			}

		}

		if (e->user_stack_size > 0 && e->user_stack_buildid_size > 0)

		if (e.user_stack_size > 0 && e.user_stack_buildid_size > 0)

			good_user_stack = true;

	}