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| author | Antonino A. Daplas <adaplas@gmail.com> | 2007-10-16 01:29:35 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 09:43:20 -0700 |
| commit | e400b6ec4ede4dc0aa8e5640425df5b29796fe0e (patch) | |
| tree | 8fbca730c850fd85fbf0f2d70daef7765ed4cb7f /drivers/char/vt_ioctl.c | |
| parent | 0058f479e52d0c0718c843cb34223bc1bfce36e1 (diff) | |
| download | linux-e400b6ec4ede4dc0aa8e5640425df5b29796fe0e.tar.gz | |
vt/vgacon: Check if screen resize request comes from userspace
Various console drivers are able to resize the screen via the con_resize() hook. This hook is also visible in userspace via the TIOCWINSZ, VT_RESIZE and VT_RESIZEX ioctl's. One particular utility, SVGATextMode, expects that con_resize() of the VGA console will always return success even if the resulting screen is not compatible with the hardware. However, this particular behavior of the VGA console, as reported in Kernel Bugzilla Bug 7513, can cause undefined behavior if the user starts with a console size larger than 80x25. To work around this problem, add an extra parameter to con_resize(). This parameter is ignored by drivers except for vgacon. If this parameter is non-zero, then the resize request came from a VT_RESIZE or VT_RESIZEX ioctl and vgacon will always return success. If this parameter is zero, vgacon will return -EINVAL if the requested size is not compatible with the hardware. The latter is the more correct behavior. With this change, SVGATextMode should still work correctly while in-kernel and stty resize calls can expect correct behavior from vgacon. Signed-off-by: Antonino Daplas <adaplas@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/vt_ioctl.c')
| -rw-r--r-- | drivers/char/vt_ioctl.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c index 7a61a2a9aafe..f69a8258095c 100644 --- a/drivers/char/vt_ioctl.c +++ b/drivers/char/vt_ioctl.c @@ -847,14 +847,24 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, case VT_RESIZE: { struct vt_sizes __user *vtsizes = up; + struct vc_data *vc; + ushort ll,cc; if (!perm) return -EPERM; if (get_user(ll, &vtsizes->v_rows) || get_user(cc, &vtsizes->v_cols)) return -EFAULT; - for (i = 0; i < MAX_NR_CONSOLES; i++) - vc_lock_resize(vc_cons[i].d, cc, ll); + + for (i = 0; i < MAX_NR_CONSOLES; i++) { + vc = vc_cons[i].d; + + if (vc) { + vc->vc_resize_user = 1; + vc_lock_resize(vc_cons[i].d, cc, ll); + } + } + return 0; } @@ -900,6 +910,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, vc_cons[i].d->vc_scan_lines = vlin; if (clin) vc_cons[i].d->vc_font.height = clin; + vc_cons[i].d->vc_resize_user = 1; vc_resize(vc_cons[i].d, cc, ll); release_console_sem(); } |