lkml.org 
[lkml]   [2012]   [May]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] compat: Fix RT signal mask corruption via sigprocmask
compat_sys_sigprocmask reads a smaller signal mask from userspace than
sigprogmask accepts for setting. So the high word of blocked.sig[0] will
be cleared, releasing any potentially blocked RT signal.

This was discovered via userspace code that relies on get/setcontext.
glibc's i386 versions of those functions use sigprogmask instead of
rt_sigprogmask to save/restore the signal mask and caused RT signal
unblocking this way.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
kernel/compat.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/compat.c b/kernel/compat.c
index 74ff849..03e491d 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -381,6 +381,8 @@ asmlinkage long compat_sys_sigprocmask(int how, compat_old_sigset_t __user *set,

if (set && get_user(s, set))
return -EFAULT;
+ s |= current->blocked.sig[0] &
+ ~((old_sigset_t)(compat_old_sigset_t)-1);
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = sys_sigprocmask(how,
--
1.7.3.4

\
 
 \ /
  Last update: 2012-05-10 00:41    [W:0.078 / U:0.332 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site