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selftests/bpf: Prevent misaligned memory access in get_stack_raw_tp test

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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: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-10-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2021-11-23 16:23:21 -08:00 committed by Daniel Borkmann
parent 3bd0233f38
commit 6c4dedb755
1 changed files with 10 additions and 4 deletions
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14
tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
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@ -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;
}