FAILED: patch "[PATCH] fbcon: Avoid OOB font access if console rotation fails" failed to apply to 5.10-stable tree

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 <[email protected]>.

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 e4ef723d8975a2694cc90733a6b888a5e2841842
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051242-unused-clone-b894@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From e4ef723d8975a2694cc90733a6b888a5e2841842 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <[email protected]>
Date: Tue, 7 Apr 2026 11:23:12 +0200
Subject: [PATCH] fbcon: Avoid OOB font access if console rotation fails

Clear the font buffer if the reallocation during console rotation fails in fbcon_rotate_font(). The putcs implementations for the rotated buffer will return early in this case. See [1] for an example.

Currently, fbcon_rotate_font() keeps the old buffer, which is too small for the rotated font. Printing to the rotated console with a high-enough character code will overflow the font buffer.

v2:
- fix typos in commit message

index 1562a8f20b4f..5348f6c6f57c 100644
@@ -46,6 +46,10 @@ int fbcon_rotate_font(struct fb_info *info, struct vc_data *vc)
 		info->fbops->fb_sync(info);
 
 	if (par->fd_size < d_cellsize * len) {
+		kfree(par->fontbuffer);
+		par->fontbuffer = NULL;
+		par->fd_size = 0;
+
 		dst = kmalloc_array(len, d_cellsize, GFP_KERNEL);
 
 		if (dst == NULL) {

@@ -54,7 +58,6 @@ int fbcon_rotate_font(struct fb_info *info, struct vc_data *vc)
 		}
 
 		par->fd_size = d_cellsize * len;
-		kfree(par->fontbuffer);
 		par->fontbuffer = dst;
 	}
 

From: Thomas Zimmermann <[email protected]>

[ Upstream commit e4ef723d8975a2694cc90733a6b888a5e2841842 ]

Clear the font buffer if the reallocation during console rotation fails in fbcon_rotate_font(). The putcs implementations for the rotated buffer will return early in this case. See [1] for an example.

Currently, fbcon_rotate_font() keeps the old buffer, which is too small for the rotated font. Printing to the rotated console with a high-enough character code will overflow the font buffer.

v2:
- fix typos in commit message

---
 drivers/video/fbdev/core/fbcon_rotate.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

index ef1d421c261a8..c1beb4a837081 100644
@@ -46,6 +46,10 @@ static int fbcon_rotate_font(struct fb_info *info, struct vc_data *vc)
 		info->fbops->fb_sync(info);
 
 	if (ops->fd_size < d_cellsize * len) {
+		kfree(ops->fontbuffer);
+		ops->fontbuffer = NULL;
+		ops->fd_size = 0;
+
 		dst = kmalloc_array(len, d_cellsize, GFP_KERNEL);
 
 		if (dst == NULL) {

@@ -54,7 +58,6 @@ static int fbcon_rotate_font(struct fb_info *info, struct vc_data *vc)
 		}
 
 		ops->fd_size = d_cellsize * len;
-		kfree(ops->fontbuffer);
 		ops->fontbuffer = dst;
 	}
 

2.53.0