On Mon, Jun 13, 2022 at 6:47 PM Ian Rogers <irogers@xxxxxxxxxx> wrote: > > bpil data is accessed assuming 64-bit alignment resulting in undefined > behavior as the data is just byte aligned. With an -fsanitize=undefined > build the following errors are observed: > > $ sudo perf record -a sleep 1 > util/bpf-event.c:310:22: runtime error: load of misaligned address 0x55f61084520f for type '__u64', which requires 8 byte alignment > 0x55f61084520f: note: pointer points here > a8 fe ff ff 3c 51 d3 c0 ff ff ff ff 04 84 d3 c0 ff ff ff ff d8 aa d3 c0 ff ff ff ff a4 c0 d3 c0 > ^ > util/bpf-event.c:311:20: runtime error: load of misaligned address 0x55f61084522f for type '__u32', which requires 4 byte alignment > 0x55f61084522f: note: pointer points here > ff ff ff ff c7 17 00 00 f1 02 00 00 1f 04 00 00 58 04 00 00 00 00 00 00 0f 00 00 00 63 02 00 00 > ^ > util/bpf-event.c:198:33: runtime error: member access within misaligned address 0x55f61084523f for type 'const struct bpf_func_info', which requires 4 byte alignment > 0x55f61084523f: note: pointer points here > 58 04 00 00 00 00 00 00 0f 00 00 00 63 02 00 00 3b 00 00 00 ab 02 00 00 44 00 00 00 14 03 00 00 > > Correct this by rouding up the data sizes and aligning the pointers. typo: rounding > > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx> > --- Makes sense. Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > tools/perf/util/bpf-utils.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/bpf-utils.c b/tools/perf/util/bpf-utils.c > index e271e05e51bc..80b1d2b3729b 100644 > --- a/tools/perf/util/bpf-utils.c > +++ b/tools/perf/util/bpf-utils.c > @@ -149,11 +149,10 @@ get_bpf_prog_info_linear(int fd, __u64 arrays) > count = bpf_prog_info_read_offset_u32(&info, desc->count_offset); > size = bpf_prog_info_read_offset_u32(&info, desc->size_offset); > > - data_len += count * size; > + data_len += roundup(count * size, sizeof(__u64)); > } > > /* step 3: allocate continuous memory */ > - data_len = roundup(data_len, sizeof(__u64)); > info_linear = malloc(sizeof(struct perf_bpil) + data_len); > if (!info_linear) > return ERR_PTR(-ENOMEM); > @@ -180,7 +179,7 @@ get_bpf_prog_info_linear(int fd, __u64 arrays) > bpf_prog_info_set_offset_u64(&info_linear->info, > desc->array_offset, > ptr_to_u64(ptr)); > - ptr += count * size; > + ptr += roundup(count * size, sizeof(__u64)); > } > > /* step 5: call syscall again to get required arrays */ > -- > 2.36.1.476.g0c4daa206d-goog >
