Fixes for 4.4

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-4.4/series b/queue-4.4/series
index ae715fe23b79515fb7396a931fff17eb930936ad..21a7e8520d0737bb391cceff50259ca6ed8f702c 100644 (file)
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -22,3 +22,4 @@ alpha-declare-virt_to_phys-and-virt_to_bus-parameter.patch
 net-6pack-fix-tx-timeout-and-slot-time.patch
 spi-fix-tegra20-build-with-config_pm-n.patch
 qnx4-work-around-gcc-false-positive-warning-bug.patch
+tty-fix-out-of-bound-vmalloc-access-in-imageblit.patch

diff --git a/queue-4.4/tty-fix-out-of-bound-vmalloc-access-in-imageblit.patch b/queue-4.4/tty-fix-out-of-bound-vmalloc-access-in-imageblit.patch
new file mode 100644 (file)
index 0000000..8175a12
--- /dev/null
+++ b/queue-4.4/tty-fix-out-of-bound-vmalloc-access-in-imageblit.patch
@@ -0,0 +1,71 @@
+From 3e77912d932c1be2c56626ca6eba1892044f82af Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 28 Jun 2021 10:45:09 -0300
+Subject: tty: Fix out-of-bound vmalloc access in imageblit
+
+From: Igor Matheus Andrade Torrente <igormtorrente@gmail.com>
+
+[ Upstream commit 3b0c406124719b625b1aba431659f5cdc24a982c ]
+
+This issue happens when a userspace program does an ioctl
+FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct
+containing only the fields xres, yres, and bits_per_pixel
+with values.
+
+If this struct is the same as the previous ioctl, the
+vc_resize() detects it and doesn't call the resize_screen(),
+leaving the fb_var_screeninfo incomplete. And this leads to
+the updatescrollmode() calculates a wrong value to
+fbcon_display->vrows, which makes the real_y() return a
+wrong value of y, and that value, eventually, causes
+the imageblit to access an out-of-bound address value.
+
+To solve this issue I made the resize_screen() be called
+even if the screen does not need any resizing, so it will
+"fix and fill" the fb_var_screeninfo independently.
+
+Cc: stable <stable@vger.kernel.org> # after 5.15-rc2 is out, give it time to bake
+Reported-and-tested-by: syzbot+858dc7a2f7ef07c2c219@syzkaller.appspotmail.com
+Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@gmail.com>
+Link: https://lore.kernel.org/r/20210628134509.15895-1-igormtorrente@gmail.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ drivers/tty/vt/vt.c | 21 +++++++++++++++++++--
+ 1 file changed, 19 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
+index 9f479b4c6491..0fab196a1d90 100644
+--- a/drivers/tty/vt/vt.c
++++ b/drivers/tty/vt/vt.c
+@@ -882,8 +882,25 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
+       new_row_size = new_cols << 1;
+       new_screen_size = new_row_size * new_rows;
+ 
+-      if (new_cols == vc->vc_cols && new_rows == vc->vc_rows)
+-              return 0;
++      if (new_cols == vc->vc_cols && new_rows == vc->vc_rows) {
++              /*
++               * This function is being called here to cover the case
++               * where the userspace calls the FBIOPUT_VSCREENINFO twice,
++               * passing the same fb_var_screeninfo containing the fields
++               * yres/xres equal to a number non-multiple of vc_font.height
++               * and yres_virtual/xres_virtual equal to number lesser than the
++               * vc_font.height and yres/xres.
++               * In the second call, the struct fb_var_screeninfo isn't
++               * being modified by the underlying driver because of the
++               * if above, and this causes the fbcon_display->vrows to become
++               * negative and it eventually leads to out-of-bound
++               * access by the imageblit function.
++               * To give the correct values to the struct and to not have
++               * to deal with possible errors from the code below, we call
++               * the resize_screen here as well.
++               */
++              return resize_screen(vc, new_cols, new_rows, user);
++      }
+ 
+       if (new_screen_size > (4 << 20))
+               return -EINVAL;
+-- 
+2.33.0
+