kernel/drivers/tty/vt/vt.c, branch linux-5.1.y

vt/fbcon: deinitialize resources in visual_init() after failed memory allocation

2019-06-09T07:16:15Z

commit a1ad1cc9704f64c169261a76e1aee1cf1ae51832 upstream. After memory allocation failure vc_allocate() doesn't clean up data which has been initialized in visual_init(). In case of fbcon this leads to divide-by-0 in fbcon_init() on next open of the same tty. memory allocation in vc_allocate() may fail here: 1097: vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_KERNEL); on next open() fbcon_init() skips vc_font.data initialization: 1088: if (!p->fontdata) { division by zero in fbcon_init() happens here: 1149: new_cols /= vc->vc_font.width; Additional check is needed in fbcon_deinit() to prevent usage of uninitialized vc_screenbuf: 1251: if (vc->vc_hi_font_mask && vc->vc_screenbuf) 1252: set_vc_hi_font(vc, false); Crash: #6 [ffffc90001eafa60] divide_error at ffffffff81a00be4 [exception RIP: fbcon_init+463] RIP: ffffffff814b860f RSP: ffffc90001eafb18 RFLAGS: 00010246 ... #7 [ffffc90001eafb60] visual_init at ffffffff8154c36e #8 [ffffc90001eafb80] vc_allocate at ffffffff8154f53c #9 [ffffc90001eafbc8] con_install at ffffffff8154f624 ... Signed-off-by: Grzegorz Halat Reviewed-by: Oleksandr Natalenko Acked-by: Bartlomiej Zolnierkiewicz Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: vt.c: Fix TIOCL_BLANKSCREEN console blanking if blankinterval == 0

2019-05-22T05:39:52Z

commit 75ddbc1fb11efac87b611d48e9802f6fe2bb2163 upstream. Previously, in the userspace, it was possible to use the "setterm" command from util-linux to blank the VT console by default, using the following command. According to the man page, > The force option keeps the screen blank even if a key is pressed. It was implemented by calling TIOCL_BLANKSCREEN. case BLANKSCREEN: ioctlarg = TIOCL_BLANKSCREEN; if (ioctl(STDIN_FILENO, TIOCLINUX, &ioctlarg)) warn(_("cannot force blank")); break; However, after Linux 4.12, this command ceased to work anymore, which is unexpected. By inspecting the kernel source, it shows that the issue was triggered by the side-effect from commit a4199f5eb809 ("tty: Disable default console blanking interval"). The console blanking is implemented by function do_blank_screen() in vt.c: "blank_state" will be initialized to "blank_normal_wait" in con_init() if AND ONLY IF ("blankinterval" > 0). If "blankinterval" is 0, "blank_state" will be "blank_off" (== 0), and a call to do_blank_screen() will always abort, even if a forced blanking is required from the user by calling TIOCL_BLANKSCREEN, the console won't be blanked. This behavior is unexpected from a user's point-of-view, since it's not mentioned in any documentation. The setterm man page suggests it will always work, and the kernel comments in uapi/linux/tiocl.h says > /* keep screen blank even if a key is pressed */ > #define TIOCL_BLANKSCREEN 14 To fix it, we simply remove the "blank_state != blank_off" check, as pointed out by Nicolas Pitre, this check doesn't logically make sense and it's safe to remove. Suggested-by: Nicolas Pitre Fixes: a4199f5eb809 ("tty: Disable default console blanking interval") Signed-off-by: Yifeng Li Cc: stable Signed-off-by: Greg Kroah-Hartman

vt: fix cursor when clearing the screen

2019-04-17T12:45:15Z

The patch a6dbe4427559 ("vt: perform safe console erase in the right order") introduced a bug. The conditional do_update_region() was replaced by a call to update_region() that does contain the conditional already, but with unwanted extra side effects such as restoring the cursor drawing. In order to reproduce the bug: - use framebuffer console with the AMDGPU driver - type "links" to start the console www browser - press 'q' and space to exit links Now the cursor will be permanently visible in the center of the screen. It will stay there until something overwrites it. The bug goes away if we change update_region() back to the conditional do_update_region(). [ nico: reworded changelog ] Signed-off-by: Mikulas Patocka Reviewed-by: Nicolas Pitre Cc: stable@vger.kernel.org Fixes: a6dbe4427559 ("vt: perform safe console erase in the right order") Signed-off-by: Greg Kroah-Hartman

vt: perform safe console erase in the right order

2019-02-12T09:46:11Z

Commit 4b4ecd9cb853 ("vt: Perform safe console erase only once") removed what appeared to be an extra call to scr_memsetw(). This missed the fact that set_origin() must be called before clearing the screen otherwise old screen content gets restored on the screen when using vgacon. Let's fix that by moving all the scrollback handling to flush_scrollback() where it logically belongs, and invoking it before the actual screen clearing in csi_J(), making the code simpler in the end. Reported-by: Matthew Whitehead Signed-off-by: Nicolas Pitre Tested-by: Matthew Whitehead Fixes: 4b4ecd9cb853 ("vt: Perform safe console erase only once") Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

Merge 5.0-rc4 into tty-next

2019-01-28T07:22:00Z

We need the tty and serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman

vt: ignore sequences that contain ':' in parameters.

2019-01-18T12:57:27Z

csi sequences can contain subparameters delimited by ':' characters. For now just ignore the whole sequence in this case. Such sequences are used by more capable terminal implementations with T.416 high color modes or extended underline rendition attributes. Also ignore sequences with private use characters '?', '>', '=' and '>' that are not at the initial position. Signed-off-by: Martin Hostettler Signed-off-by: Greg Kroah-Hartman

vt: ignore csi sequences with intermediate characters.

2019-01-18T12:57:27Z

Various csi sequences contain intermediate characters between the parameters and the final character. Introduce a additional state that cleanly ignores these sequences. This allows the vt to ignore these sequences used by more capable terminal implementations such as "request mode", etc. Signed-off-by: Martin Hostettler Signed-off-by: Greg Kroah-Hartman

vt: Implement parsing for >, =, < private sequences.

2019-01-18T12:56:41Z

Private sequences can start with '>', '=' and (in theory) '<'. Implement correct parsing for these. The newly parsable sequences are cleanly ignored as it is customary with terminal emulators. This allows the vt to ignore various sequences used by more capable terminal implementations such as "Secondary Device Attributes", "Tertiary Device Attributes" and various advanced configuration commands that don't have dedicated terminfo entries. Signed-off-by: Martin Hostettler Signed-off-by: Greg Kroah-Hartman

vt: refactor vc_ques to allow of other private sequences.

2019-01-18T12:52:41Z

The vc_ques keeps track if a csi sequence is a private DEC control function beginning with '?'. Nowadays some private control functions begin with '>' and '='. Switch the code to instead use a new 3-bit vc_priv that allows for all private use parameter prefixes. Signed-off-by: Martin Hostettler Signed-off-by: Greg Kroah-Hartman

vt: annotate implicit fall throughs

2019-01-18T12:48:52Z

There is a plan to build the kernel with -Wimplicit-fallthrough and these places in the code produced warnings (W=1). Fix them up. This commit remove the following warning: drivers/tty/vt/vt.c:2112:6: warning: this statement may fall through [-Wimplicit-fallthrough=] drivers/tty/vt/vt.c:2237:6: warning: this statement may fall through [-Wimplicit-fallthrough=] Signed-off-by: Mathieu Malaterre Acked-by: Gustavo A. R. Silva Signed-off-by: Greg Kroah-Hartman