diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2006-12-08 13:36:04 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-08 19:28:38 +0300 |
| commit | 24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517 (patch) | |
| tree | 2ff478b1925159eeac007913c2a8f19d5f5e6010 /fs | |
| parent | 562f9c574e0707f9159a729ea41faf53b221cd30 (diff) | |
| download | linux-24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517.tar.xz | |
[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.c | 14 | ||||
| -rw-r--r-- | fs/open.c | 1 |
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; } |