From: Andrii Nakryiko andrii@kernel.org
mainline inclusion from mainline-5.17-rc1 commit 6c4dedb7550aafd094f7d803668fd039545f4e57 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 (cherry picked from commit 6c4dedb7550aafd094f7d803668fd039545f4e57) Signed-off-by: Wang Yufen wangyufen@huawei.com --- .../selftests/bpf/prog_tests/get_stack_raw_tp.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c index 522237aa4470..47f1020fa5b3 100644 --- a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c +++ b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c @@ -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; }