| Message ID | 1500416736-49829-15-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 18 Jul 2017, Kees Cook wrote: > For a secureexec, before memory layout selection has happened, reset the > stack rlimit to something sane to avoid the caller having control over > the resulting layouts. > > $ ulimit -s > 8192 > $ ulimit -s unlimited > $ /bin/sh -c 'ulimit -s' > unlimited > $ sudo /bin/sh -c 'ulimit -s' > 8192 > > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: James Morris <james.l.morris@oracle.com>
diff --git a/fs/exec.c b/fs/exec.c index 45418d6ec583..4227c1e56566 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1349,6 +1349,18 @@ void setup_new_exec(struct linux_binprm * bprm) */ bprm->secureexec |= bprm->cap_elevated; + if (bprm->secureexec) { + /* + * For secureexec, reset the stack limit to sane default to + * avoid bad behavior from the prior rlimits. This has to + * happen before arch_pick_mmap_layout(), which examines + * RLIMIT_STACK, but after the point of no return to avoid + * needing to clean up the change on failure. + */ + if (current->signal->rlim[RLIMIT_STACK].rlim_cur > _STK_LIM) + current->signal->rlim[RLIMIT_STACK].rlim_cur = _STK_LIM; + } + arch_pick_mmap_layout(current->mm); current->sas_ss_sp = current->sas_ss_size = 0;
For a secureexec, before memory layout selection has happened, reset the stack rlimit to something sane to avoid the caller having control over the resulting layouts. $ ulimit -s 8192 $ ulimit -s unlimited $ /bin/sh -c 'ulimit -s' unlimited $ sudo /bin/sh -c 'ulimit -s' 8192 Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Kees Cook <keescook@chromium.org> --- fs/exec.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)