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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2006-12-08 02:36:04 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 08:28:38 -0800
commit24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517 (patch)
tree2ff478b1925159eeac007913c2a8f19d5f5e6010 /kernel/exit.c
parent562f9c574e0707f9159a729ea41faf53b221cd30 (diff)
downloadlinux-24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517.tar.gz
[PATCH] tty: ->signal->tty locking
Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 4e3f919edc4..fa235779b6a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -384,9 +384,7 @@ void daemonize(const char *name, ...)
exit_mm(current);
set_special_pids(1, 1);
- mutex_lock(&tty_mutex);
- current->signal->tty = NULL;
- mutex_unlock(&tty_mutex);
+ proc_clear_tty(current);
/* Block and flush all signals */
sigfillset(&blocked);