FAILED: patch "[PATCH] fbdev: bitblit: Fix glyph clipping when fbcon pans" failed to apply to 5.10-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 06fccf840640d8f6b0e08a1756f8d2f0435b4cbe
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107062710-failed-5.10-06fccf840640@kernel.org' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 06fccf840640d8f6b0e08a1756f8d2f0435b4cbe Mon Sep 17 00:00:00 2001
From: Tingjie Zhong <catme0w@live.cn>
Date: Tue, 20 Oct 2026 10:46:57 -0600
Subject: [PATCH] fbdev: bitblit: Fix glyph clipping when fbcon pans

Commit 3637d34b35b2 ("fbdev: Add bounds checking in bit_putcs to fix
vmalloc-out-of-bounds") made bit_putcs() clip glyphs to var.yres. When
fbcon scrolls by panning, it draws text rows up to var.yres_virtual,
so after the first pan most new text is not drawn until the next full
redraw. This affects fbdev drivers that set FBINFO_HWACCEL_YPAN or
FBINFO_HWACCEL_YWRAP, such as vesafb with the ypan option, when
CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION=y.

Clip to GETVYRES() instead, which fbcon_ud.c and fbcon_ccw.c already
use as the drawing area height. When fbcon does not pan, GETVYRES()
returns var.yres, keeping the existing bound. When fbcon pans, it
returns var.yres_virtual, which the framebuffer memory must cover
anyway for panning to work.

Fixes: 3637d34b35b2 ("fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds")
Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
Closes: https://lore.kernel.org/linux-fbdev/b8b52ffd-ecec-4fba-b432-ba32135c2f99@suse.de/
Tested-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Tingjie Zhong <catme0w@live.cn>
Signed-off-by: Helge Deller <deller@gmx.de>
---
 drivers/video/fbdev/core/bitblit.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/core/bitblit.c b/drivers/video/fbdev/core/bitblit.c
index 03b3b18e1fe92..590d12bbf30dd 100644
--- a/drivers/video/fbdev/core/bitblit.c
+++ b/drivers/video/fbdev/core/bitblit.c
@@ -18,6 +18,7 @@
 #include <linux/console.h>
 #include <asm/types.h>
 #include "fbcon.h"
+#include "fbcon_rotate.h"
 
 /*
  * Accelerated handlers.
@@ -150,7 +151,9 @@ static void bit_putcs(struct vc_data *vc, struct fb_info *info,
 		      const unsigned short *s, int count, int yy, int xx,
 		      int fg, int bg)
 {
+	struct fbcon_par *par = info->fbcon_par;
 	struct fb_image image;
+	u32 vyres = GETVYRES(par->p, info);
 	u32 width = DIV_ROUND_UP(vc->vc_font.width, 8);
 	u32 cellsize = width * vc->vc_font.height;
 	u32 maxcnt = info->pixmap.size/cellsize;
@@ -167,10 +170,10 @@ static void bit_putcs(struct vc_data *vc, struct fb_info *info,
 	image.height = vc->vc_font.height;
 	image.depth = 1;
 
-	if (image.dy >= info->var.yres)
+	if (image.dy >= vyres)
 		return;
 
-	image.height = min(image.height, info->var.yres - image.dy);
+	image.height = min(image.height, vyres - image.dy);
 
 	if (attribute) {
 		buf = kmalloc(cellsize, GFP_ATOMIC);
-- 
2.53.0