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authorOleg Nesterov <oleg@redhat.com>2019-06-28 12:06:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-06-29 16:43:45 +0800
commit97abc889ee296faf95ca0e978340fb7b942a3e32 (patch)
tree0314a1067a06976c8826b9e4e70aef45ad9129ec /fs/aio.c
parent867bfa4a5fcee66f2b25639acae718e8b28b25a5 (diff)
signal: remove the wrong signal_pending() check in restore_user_sigmask()
This is the minimal fix for stable, I'll send cleanups later. Commit 854a6ed56839 ("signal: Add restore_user_sigmask()") introduced the visible change which breaks user-space: a signal temporary unblocked by set_user_sigmask() can be delivered even if the caller returns success or timeout. Change restore_user_sigmask() to accept the additional "interrupted" argument which should be used instead of signal_pending() check, and update the callers. Eric said: : For clarity. I don't think this is required by posix, or fundamentally to : remove the races in select. It is what linux has always done and we have : applications who care so I agree this fix is needed. : : Further in any case where the semantic change that this patch rolls back : (aka where allowing a signal to be delivered and the select like call to : complete) would be advantage we can do as well if not better by using : signalfd. : : Michael is there any chance we can get this guarantee of the linux : implementation of pselect and friends clearly documented. The guarantee : that if the system call completes successfully we are guaranteed that no : signal that is unblocked by using sigmask will be delivered? Link: http://lkml.kernel.org/r/20190604134117.GA29963@redhat.com Fixes: 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add restore_user_sigmask()") Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Eric Wong <e@80x24.org> Tested-by: Eric Wong <e@80x24.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Deepa Dinamani <deepa.kernel@gmail.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jason Baron <jbaron@akamai.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: David Laight <David.Laight@ACULAB.COM> Cc: <stable@vger.kernel.org> [5.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/aio.c')
-rw-r--r--fs/aio.c28
1 files changed, 20 insertions, 8 deletions
diff --git a/fs/aio.c b/fs/aio.c
index 3490d1fa0e16..c1e581dd32f5 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -2095,6 +2095,7 @@ SYSCALL_DEFINE6(io_pgetevents,
struct __aio_sigset ksig = { NULL, };
sigset_t ksigmask, sigsaved;
struct timespec64 ts;
+ bool interrupted;
int ret;
if (timeout && unlikely(get_timespec64(&ts, timeout)))
@@ -2108,8 +2109,10 @@ 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)
+
+ interrupted = signal_pending(current);
+ restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted);
+ if (interrupted && !ret)
ret = -ERESTARTNOHAND;
return ret;
@@ -2128,6 +2131,7 @@ SYSCALL_DEFINE6(io_pgetevents_time32,
struct __aio_sigset ksig = { NULL, };
sigset_t ksigmask, sigsaved;
struct timespec64 ts;
+ bool interrupted;
int ret;
if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
@@ -2142,8 +2146,10 @@ 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)
+
+ interrupted = signal_pending(current);
+ restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted);
+ if (interrupted && !ret)
ret = -ERESTARTNOHAND;
return ret;
@@ -2193,6 +2199,7 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents,
struct __compat_aio_sigset ksig = { NULL, };
sigset_t ksigmask, sigsaved;
struct timespec64 t;
+ bool interrupted;
int ret;
if (timeout && get_old_timespec32(&t, timeout))
@@ -2206,8 +2213,10 @@ 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)
+
+ interrupted = signal_pending(current);
+ restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted);
+ if (interrupted && !ret)
ret = -ERESTARTNOHAND;
return ret;
@@ -2226,6 +2235,7 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
struct __compat_aio_sigset ksig = { NULL, };
sigset_t ksigmask, sigsaved;
struct timespec64 t;
+ bool interrupted;
int ret;
if (timeout && get_timespec64(&t, timeout))
@@ -2239,8 +2249,10 @@ 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)
+
+ interrupted = signal_pending(current);
+ restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted);
+ if (interrupted && !ret)
ret = -ERESTARTNOHAND;
return ret;