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VT ioctl race fix

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When calling the RELDISP VT ioctl, we are reading vt_newvt while the
console workqueue could be messing with it (through change_console()).  We
fix this race by taking the console semaphore before reading vt_newvt.

Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Acked-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Samuel Ortiz 2007-10-01 01:20:12 -07:00 committed by Linus Torvalds
parent 4047727e5a
commit 8792f961ba
1 changed files with 5 additions and 3 deletions
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8
drivers/char/vt_ioctl.c
View file

@ -770,6 +770,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
/*
* Switching-from response
*/
acquire_console_sem();
if (vc->vt_newvt >= 0) {
if (arg == 0)
/*
@ -784,7 +785,6 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
* complete the switch.
*/
int newvt;
acquire_console_sem();
newvt = vc->vt_newvt;
vc->vt_newvt = -1;
i = vc_allocate(newvt);
@ -798,7 +798,6 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
* other console switches..
*/
complete_change_console(vc_cons[newvt].d);
release_console_sem();
}
}
@ -810,9 +809,12 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
/*
* If it's just an ACK, ignore it
*/
if (arg != VT_ACKACQ)
if (arg != VT_ACKACQ) {
release_console_sem();
return -EINVAL;
}
}
release_console_sem();
return 0;