Messages in this thread | | | Subject | Re: [PATCH] waitid(): Avoid unbalanced user_access_end() on access_ok() error | From | David Daney <> | Date | Fri, 20 Oct 2017 08:11:40 -0700 |
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On 10/20/2017 07:36 AM, Kees Cook wrote: > As pointed out by Linus and David, the earlier waitid() fix resulted in a > (currently harmless) unbalanced user_access_end() call. This fixes it to > just directly return EFAULT on access_ok() failure. > > Fixes: 96ca579a1ecc ("waitid(): Add missing access_ok() checks") > Cc: Al Viro <viro@zeniv.linux.org.uk> > Cc: David Daney <ddaney@caviumnetworks.com> > Signed-off-by: Kees Cook <keescook@chromium.org>
Thanks Kees, this looks better to me ...
Acked-by: David Daney <david.daney@cavium.com>
> --- > This seems best to get fixed up now (in the same release where it was > introduced) before it tries to bite us at some later time. > --- > kernel/exit.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/exit.c b/kernel/exit.c > index cf28528842bc..f6cad39f35df 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1611,7 +1611,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, > return err; > > if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) > - goto Efault; > + return -EFAULT; > > user_access_begin(); > unsafe_put_user(signo, &infop->si_signo, Efault); > @@ -1739,7 +1739,7 @@ COMPAT_SYSCALL_DEFINE5(waitid, > return err; > > if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) > - goto Efault; > + return -EFAULT; > > user_access_begin(); > unsafe_put_user(signo, &infop->si_signo, Efault); >
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