It's been 2 weeks and this fix hasn't appeared in mmots / mmotm. I also noticed it's missing Cc: for stable@ (below) Deepa Dinamani <deepa.kernel@xxxxxxxxx> wrote: > For all the syscalls that receive a sigmask from the userland, > the user sigmask is to be in effect through the syscall execution. > At the end of syscall, sigmask of the current process is restored > to what it was before the switch over to user sigmask. > But, for this to be true in practice, the sigmask should be restored > only at the the point we change the saved_sigmask. Anything before > that loses signals. And, anything after is just pointless as the > signal is already lost by restoring the sigmask. > > The inherent issue was detected because of a regression caused by > 854a6ed56839a. > The patch moved the signal_pending() check closer to restoring of the > user sigmask. But, it failed to update the error code accordingly. > > Detailed issue discussion permalink: > https://lore.kernel.org/linux-fsdevel/20190427093319.sgicqik2oqkez3wk@dcvr/ > > Note that the patch returns interrupted errors (EINTR, ERESTARTNOHAND, > etc) only when there is no other error. If there is a signal and an error > like EINVAL, the syscalls return -EINVAL rather than the interrupted > error codes. > > The sys_io_uring_enter() seems to be returning success when there is > a signal and the queue is not empty. This seems to be a bug. I will > follow up with a separate patch for that. > > Reported-by: Eric Wong <e@xxxxxxxxx> > Fixes: 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add restore_user_sigmask()") > Signed-off-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx> > Reviewed-by: Davidlohr Bueso <dbueso@xxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 5.0.x Cc: <stable@xxxxxxxxxxxxxxx> # 5.1.x > --- > > fs/aio.c | 24 ++++++++++++------------ > fs/eventpoll.c | 14 ++++++++++---- > fs/io_uring.c | 9 ++++++--- > fs/select.c | 37 +++++++++++++++++++++---------------- > include/linux/signal.h | 2 +- > kernel/signal.c | 13 ++++++++++--- > 6 files changed, 60 insertions(+), 39 deletions(-) > > diff --git a/fs/aio.c b/fs/aio.c > index 3490d1fa0e16..ebd2b1980161 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -2095,7 +2095,7 @@ SYSCALL_DEFINE6(io_pgetevents, > struct __aio_sigset ksig = { NULL, }; > sigset_t ksigmask, sigsaved; > struct timespec64 ts; > - int ret; > + int ret, signal_detected; > > if (timeout && unlikely(get_timespec64(&ts, timeout))) > return -EFAULT; > @@ -2108,8 +2108,8 @@ SYSCALL_DEFINE6(io_pgetevents, > return ret; > > ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL); > - restore_user_sigmask(ksig.sigmask, &sigsaved); > - if (signal_pending(current) && !ret) > + signal_detected = restore_user_sigmask(ksig.sigmask, &sigsaved); > + if (signal_detected && !ret) > ret = -ERESTARTNOHAND; > > return ret; > @@ -2128,7 +2128,7 @@ SYSCALL_DEFINE6(io_pgetevents_time32, > struct __aio_sigset ksig = { NULL, }; > sigset_t ksigmask, sigsaved; > struct timespec64 ts; > - int ret; > + int ret, signal_detected; > > if (timeout && unlikely(get_old_timespec32(&ts, timeout))) > return -EFAULT; > @@ -2142,8 +2142,8 @@ SYSCALL_DEFINE6(io_pgetevents_time32, > return ret; > > ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL); > - restore_user_sigmask(ksig.sigmask, &sigsaved); > - if (signal_pending(current) && !ret) > + signal_detected = restore_user_sigmask(ksig.sigmask, &sigsaved); > + if (signal_detected && !ret) > ret = -ERESTARTNOHAND; > > return ret; > @@ -2193,7 +2193,7 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents, > struct __compat_aio_sigset ksig = { NULL, }; > sigset_t ksigmask, sigsaved; > struct timespec64 t; > - int ret; > + int ret, signal_detected; > > if (timeout && get_old_timespec32(&t, timeout)) > return -EFAULT; > @@ -2206,8 +2206,8 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents, > return ret; > > ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL); > - restore_user_sigmask(ksig.sigmask, &sigsaved); > - if (signal_pending(current) && !ret) > + signal_detected = restore_user_sigmask(ksig.sigmask, &sigsaved); > + if (signal_detected && !ret) > ret = -ERESTARTNOHAND; > > return ret; > @@ -2226,7 +2226,7 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64, > struct __compat_aio_sigset ksig = { NULL, }; > sigset_t ksigmask, sigsaved; > struct timespec64 t; > - int ret; > + int ret, signal_detected; > > if (timeout && get_timespec64(&t, timeout)) > return -EFAULT; > @@ -2239,8 +2239,8 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64, > return ret; > > ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL); > - restore_user_sigmask(ksig.sigmask, &sigsaved); > - if (signal_pending(current) && !ret) > + signal_detected = restore_user_sigmask(ksig.sigmask, &sigsaved); > + if (signal_detected && !ret) > ret = -ERESTARTNOHAND; > > return ret; > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > index 4a0e98d87fcc..fe5a0724b417 100644 > --- a/fs/eventpoll.c > +++ b/fs/eventpoll.c > @@ -2317,7 +2317,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, > int, maxevents, int, timeout, const sigset_t __user *, sigmask, > size_t, sigsetsize) > { > - int error; > + int error, signal_detected; > sigset_t ksigmask, sigsaved; > > /* > @@ -2330,7 +2330,10 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, > > error = do_epoll_wait(epfd, events, maxevents, timeout); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > + > + if (signal_detected && !error) > + error = -EINTR; > > return error; > } > @@ -2342,7 +2345,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd, > const compat_sigset_t __user *, sigmask, > compat_size_t, sigsetsize) > { > - long err; > + long err, signal_detected; > sigset_t ksigmask, sigsaved; > > /* > @@ -2355,7 +2358,10 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd, > > err = do_epoll_wait(epfd, events, maxevents, timeout); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > + > + if (signal_detected && !err) > + err = -EINTR; > > return err; > } > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 452e35357865..8fd4710f371d 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -2195,7 +2195,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, > struct io_cq_ring *ring = ctx->cq_ring; > sigset_t ksigmask, sigsaved; > DEFINE_WAIT(wait); > - int ret; > + int ret, signal_detected; > > /* See comment at the top of this file */ > smp_rmb(); > @@ -2234,8 +2234,11 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, > > finish_wait(&ctx->wait, &wait); > > - if (sig) > - restore_user_sigmask(sig, &sigsaved); > + if (sig) { > + signal_detected = restore_user_sigmask(sig, &sigsaved); > + if (signal_detected && !ret) > + ret = -EINTR; > + } > > return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.tail) ? ret : 0; > } > diff --git a/fs/select.c b/fs/select.c > index 6cbc9ff56ba0..da9cfea35159 100644 > --- a/fs/select.c > +++ b/fs/select.c > @@ -732,7 +732,7 @@ static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, > { > sigset_t ksigmask, sigsaved; > struct timespec64 ts, end_time, *to = NULL; > - int ret; > + int ret, signal_detected; > > if (tsp) { > switch (type) { > @@ -760,7 +760,9 @@ static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, > ret = core_sys_select(n, inp, outp, exp, to); > ret = poll_select_copy_remaining(&end_time, tsp, type, ret); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > + if (signal_detected && !ret) > + ret = -EINTR; > > return ret; > } > @@ -1089,7 +1091,7 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, > { > sigset_t ksigmask, sigsaved; > struct timespec64 ts, end_time, *to = NULL; > - int ret; > + int ret, signal_detected; > > if (tsp) { > if (get_timespec64(&ts, tsp)) > @@ -1106,10 +1108,10 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, > > ret = do_sys_poll(ufds, nfds, to); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > > /* We can restart this syscall, usually */ > - if (ret == -EINTR) > + if (ret == -EINTR || (signal_detected && !ret)) > ret = -ERESTARTNOHAND; > > ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret); > @@ -1125,7 +1127,7 @@ SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, unsigned int, nfds, > { > sigset_t ksigmask, sigsaved; > struct timespec64 ts, end_time, *to = NULL; > - int ret; > + int ret, signal_detected; > > if (tsp) { > if (get_old_timespec32(&ts, tsp)) > @@ -1142,10 +1144,10 @@ SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, unsigned int, nfds, > > ret = do_sys_poll(ufds, nfds, to); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > > /* We can restart this syscall, usually */ > - if (ret == -EINTR) > + if (ret == -EINTR || (signal_detected && !ret)) > ret = -ERESTARTNOHAND; > > ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret); > @@ -1324,7 +1326,7 @@ static long do_compat_pselect(int n, compat_ulong_t __user *inp, > { > sigset_t ksigmask, sigsaved; > struct timespec64 ts, end_time, *to = NULL; > - int ret; > + int ret, signal_detected; > > if (tsp) { > switch (type) { > @@ -1352,7 +1354,10 @@ static long do_compat_pselect(int n, compat_ulong_t __user *inp, > ret = compat_core_sys_select(n, inp, outp, exp, to); > ret = poll_select_copy_remaining(&end_time, tsp, type, ret); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > + > + if (signal_detected && !ret) > + ret = -EINTR; > > return ret; > } > @@ -1408,7 +1413,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, > { > sigset_t ksigmask, sigsaved; > struct timespec64 ts, end_time, *to = NULL; > - int ret; > + int ret, signal_detected; > > if (tsp) { > if (get_old_timespec32(&ts, tsp)) > @@ -1425,10 +1430,10 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, > > ret = do_sys_poll(ufds, nfds, to); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > > /* We can restart this syscall, usually */ > - if (ret == -EINTR) > + if (ret == -EINTR || (signal_detected && !ret)) > ret = -ERESTARTNOHAND; > > ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret); > @@ -1444,7 +1449,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, struct pollfd __user *, ufds, > { > sigset_t ksigmask, sigsaved; > struct timespec64 ts, end_time, *to = NULL; > - int ret; > + int ret, signal_detected; > > if (tsp) { > if (get_timespec64(&ts, tsp)) > @@ -1461,10 +1466,10 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, struct pollfd __user *, ufds, > > ret = do_sys_poll(ufds, nfds, to); > > - restore_user_sigmask(sigmask, &sigsaved); > + signal_detected = restore_user_sigmask(sigmask, &sigsaved); > > /* We can restart this syscall, usually */ > - if (ret == -EINTR) > + if (ret == -EINTR || (signal_detected && !ret)) > ret = -ERESTARTNOHAND; > > ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret); > diff --git a/include/linux/signal.h b/include/linux/signal.h > index 9702016734b1..1d36e8629edf 100644 > --- a/include/linux/signal.h > +++ b/include/linux/signal.h > @@ -275,7 +275,7 @@ extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struc > extern int sigprocmask(int, sigset_t *, sigset_t *); > extern int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set, > sigset_t *oldset, size_t sigsetsize); > -extern void restore_user_sigmask(const void __user *usigmask, > +extern int restore_user_sigmask(const void __user *usigmask, > sigset_t *sigsaved); > extern void set_current_blocked(sigset_t *); > extern void __set_current_blocked(const sigset_t *); > diff --git a/kernel/signal.c b/kernel/signal.c > index e46d527ff467..ea0321b70315 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -2906,15 +2906,21 @@ EXPORT_SYMBOL(set_compat_user_sigmask); > * usigmask: sigmask passed in from userland. > * sigsaved: saved sigmask when the syscall started and changed the sigmask to > * usigmask. > + * returns 1 in case a pending signal is detected. > + * > + * Users of the api need to adjust their return values based on whether the > + * signal was detected here. If a signal is detected, it is delivered to the > + * userspace. So without an error like -EINTR, userspace might fail to > + * adjust the flow of execution. > * > * This is useful for syscalls such as ppoll, pselect, io_pgetevents and > * epoll_pwait where a new sigmask is passed in from userland for the syscalls. > */ > -void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved) > +int restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved) > { > > if (!usigmask) > - return; > + return 0; > /* > * When signals are pending, do not restore them here. > * Restoring sigmask here can lead to delivering signals that the above > @@ -2923,7 +2929,7 @@ void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved) > if (signal_pending(current)) { > current->saved_sigmask = *sigsaved; > set_restore_sigmask(); > - return; > + return 1; > } > > /* > @@ -2931,6 +2937,7 @@ void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved) > * saved_sigmask when signals are not pending. > */ > set_current_blocked(sigsaved); > + return 0; > } > EXPORT_SYMBOL(restore_user_sigmask); > > -- > 2.17.1
