From: Roland Dreier <[email protected]>
=====================================================================
| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|
=====================================================================
commit 243b422af9ea9af4ead07a8ad54c90d4f9b6081a upstream.
Commit da48524eb206 ("Prevent rt_sigqueueinfo and rt_tgsigqueueinfo
from spoofing the signal code") made the check on si_code too strict.
There are several legitimate places where glibc wants to queue a
negative si_code different from SI_QUEUE:
- This was first noticed with glibc's aio implementation, which wants
to queue a signal with si_code SI_ASYNCIO; the current kernel
causes glibc's tst-aio4 test to fail because rt_sigqueueinfo()
fails with EPERM.
- Further examination of the glibc source shows that getaddrinfo_a()
wants to use SI_ASYNCNL (which the kernel does not even define).
The timer_create() fallback code wants to queue signals with SI_TIMER.
As suggested by Oleg Nesterov <[email protected]>, loosen the check to
forbid only the problematic SI_TKILL case.
Reported-by: Klaus Dittrich <[email protected]>
Acked-by: Julien Tinnes <[email protected]>
Signed-off-by: Roland Dreier <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
kernel/signal.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index 704c030..137a333 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2411,7 +2411,7 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
/* 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 != SI_QUEUE) {
+ if (info.si_code >= 0 || info.si_code == SI_TKILL) {
/* We used to allow any < 0 si_code */
WARN_ON_ONCE(info.si_code < 0);
return -EPERM;
@@ -2431,7 +2431,7 @@ long 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 != SI_QUEUE) {
+ if (info->si_code >= 0 || info->si_code == SI_TKILL) {
/* We used to allow any < 0 si_code */
WARN_ON_ONCE(info->si_code < 0);
return -EPERM;
--
1.7.4.4
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