On Mon, Aug 10, 2020 at 8:40 AM Jianlin Lv <Jianlin.Lv@xxxxxxx> wrote: > > test_progs reports the segmentation fault as below > > $ sudo ./test_progs -t mmap --verbose > test_mmap:PASS:skel_open_and_load 0 nsec > ...... > test_mmap:PASS:adv_mmap1 0 nsec > test_mmap:PASS:adv_mmap2 0 nsec > test_mmap:PASS:adv_mmap3 0 nsec > test_mmap:PASS:adv_mmap4 0 nsec > Segmentation fault > > This issue was triggered because mmap() and munmap() used inconsistent > length parameters; mmap() creates a new mapping of 3*page_size, but the > length parameter set in the subsequent re-map and munmap() functions is > 4*page_size; this leads to the destruction of the process space. > > To fix this issue, first create 4 pages of anonymous mapping,then do all > the mmap() with MAP_FIXED. > > Another issue is that when unmap the second page fails, the length > parameter to delete tmp1 mappings should be 4*page_size. > > Signed-off-by: Jianlin Lv <Jianlin.Lv@xxxxxxx> > --- LGTM, thanks for the fix! Acked-by: Andrii Nakryiko <andriin@xxxxxx> > v2: > - Update commit messages > - Create 4 pages of anonymous mapping that serve the subsequent mmap() > --- > tools/testing/selftests/bpf/prog_tests/mmap.c | 19 +++++++++++++------ > 1 file changed, 13 insertions(+), 6 deletions(-) > [...]
