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tty: vt: push console lock from tioclinux() down to 2 functions

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Avoid costly user copies under the console lock. So push the lock down
from tioclinux() to sel_loadlut() and set_vesa_blanking().

It is now obvious what is actually protected.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-7-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE) 2024-01-22 12:03:20 +01:00 committed by Greg Kroah-Hartman
parent a0b8a16812
commit d321cd13f6
2 changed files with 14 additions and 10 deletions
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11
drivers/tty/vt/selection.c
View File

@ -113,15 +113,22 @@ static inline int inword(const u32 c)
* sel_loadlut() - load the LUT table
* @lut: user table
*
* Load the LUT table from user space. The caller must hold the console
* lock. Make a temporary copy so a partial update doesn't make a mess.
* Load the LUT table from user space. Make a temporary copy so a partial
* update doesn't make a mess.
*
* Locking: The console lock is acquired.
*/
int sel_loadlut(u32 __user *lut)
{
u32 tmplut[ARRAY_SIZE(inwordLut)];
if (copy_from_user(tmplut, lut, sizeof(inwordLut)))
return -EFAULT;
console_lock();
memcpy(inwordLut, tmplut, sizeof(inwordLut));
console_unlock();
return 0;
}

13
drivers/tty/vt/vt.c
View File

@ -3162,10 +3162,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
case TIOCL_SELLOADLUT:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
console_lock();
ret = sel_loadlut(param_aligned32);
console_unlock();
break;
return sel_loadlut(param_aligned32);
case TIOCL_GETSHIFTSTATE:
/*
* Make it possible to react to Shift+Mousebutton. Note that
@ -3181,10 +3178,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
console_unlock();
return put_user(data, p);
case TIOCL_SETVESABLANK:
console_lock();
ret = set_vesa_blanking(param);
console_unlock();
break;
return set_vesa_blanking(param);
case TIOCL_GETKMSGREDIRECT:
data = vt_get_kmsg_redirect();
return put_user(data, p);
@ -4270,7 +4264,10 @@ static int set_vesa_blanking(u8 __user *mode_user)
if (get_user(mode, mode_user))
return -EFAULT;
console_lock();
vesa_blank_mode = (mode < 4) ? mode : 0;
console_unlock();
return 0;
}