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Subject[PATCH 3.12 88/88] signal: remove warning about using SI_TKILL in rt_[tg]sigqueueinfo
Date
From: Vladimir Davydov <vdavydov@parallels.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 69828dce7af2cb6d08ef5a03de687d422fb7ec1f upstream.

Sending SI_TKILL from rt_[tg]sigqueueinfo was deprecated, so now we issue
a warning on the first attempt of doing it. We use WARN_ON_ONCE, which is
not informative and, what is worse, taints the kernel, making the trinity
syscall fuzzer complain false-positively from time to time.

It does not look like we need this warning at all, because the behaviour
changed quite a long time ago (2.6.39), and if an application relies on
the old API, it gets EPERM anyway and can issue a warning by itself.

So let us zap the warning in kernel.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
kernel/signal.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index e99136208d7e..1a1b0e88c23d 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3004,11 +3004,9 @@ static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info)
* Nor can they impersonate a kill()/tgkill(), which adds source info.
*/
if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
- (task_pid_vnr(current) != pid)) {
- /* We used to allow any < 0 si_code */
- WARN_ON_ONCE(info->si_code < 0);
+ (task_pid_vnr(current) != pid))
return -EPERM;
- }
+
info->si_signo = sig;

/* POSIX.1b doesn't mention process groups. */
@@ -3053,12 +3051,10 @@ static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
/* Not even root can pretend to send signals from the kernel.
* Nor can they impersonate a kill()/tgkill(), which adds source info.
*/
- if (((info->si_code >= 0 || info->si_code == SI_TKILL)) &&
- (task_pid_vnr(current) != pid)) {
- /* We used to allow any < 0 si_code */
- WARN_ON_ONCE(info->si_code < 0);
+ if ((info->si_code >= 0 || info->si_code == SI_TKILL) &&
+ (task_pid_vnr(current) != pid))
return -EPERM;
- }
+
info->si_signo = sig;

return do_send_specific(tgid, pid, sig, info);
--
2.9.1
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