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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 /fs
parent562f9c574e0707f9159a729ea41faf53b221cd30 (diff)
downloadblackbird-op-linux-24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517.tar.gz
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[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 'fs')
-rw-r--r--fs/dquot.c14
-rw-r--r--fs/open.c1
2 files changed, 9 insertions, 6 deletions
diff --git a/fs/dquot.c b/fs/dquot.c
index f9cd5e23ebdf..89066b19124d 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -828,6 +828,7 @@ static inline int need_print_warning(struct dquot *dquot)
static void print_warning(struct dquot *dquot, const char warntype)
{
char *msg = NULL;
+ struct tty_struct *tty;
int flag = (warntype == BHARDWARN || warntype == BSOFTLONGWARN) ? DQ_BLKS_B :
((warntype == IHARDWARN || warntype == ISOFTLONGWARN) ? DQ_INODES_B : 0);
@@ -835,14 +836,15 @@ static void print_warning(struct dquot *dquot, const char warntype)
return;
mutex_lock(&tty_mutex);
- if (!current->signal->tty)
+ tty = get_current_tty();
+ if (!tty)
goto out_lock;
- tty_write_message(current->signal->tty, dquot->dq_sb->s_id);
+ tty_write_message(tty, dquot->dq_sb->s_id);
if (warntype == ISOFTWARN || warntype == BSOFTWARN)
- tty_write_message(current->signal->tty, ": warning, ");
+ tty_write_message(tty, ": warning, ");
else
- tty_write_message(current->signal->tty, ": write failed, ");
- tty_write_message(current->signal->tty, quotatypes[dquot->dq_type]);
+ tty_write_message(tty, ": write failed, ");
+ tty_write_message(tty, quotatypes[dquot->dq_type]);
switch (warntype) {
case IHARDWARN:
msg = " file limit reached.\r\n";
@@ -863,7 +865,7 @@ static void print_warning(struct dquot *dquot, const char warntype)
msg = " block quota exceeded.\r\n";
break;
}
- tty_write_message(current->signal->tty, msg);
+ tty_write_message(tty, msg);
out_lock:
mutex_unlock(&tty_mutex);
}
diff --git a/fs/open.c b/fs/open.c
index 89e0c237a636..3b56192816ca 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1087,6 +1087,7 @@ EXPORT_SYMBOL(sys_close);
asmlinkage long sys_vhangup(void)
{
if (capable(CAP_SYS_TTY_CONFIG)) {
+ /* XXX: this needs locking */
tty_vhangup(current->signal->tty);
return 0;
}
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