From 9b2f5ef00e852f8e8902a4d4f73aeedc60220c12 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Mon, 22 Sep 2025 15:45:54 +0200 Subject: [PATCH] fbcon: Fix OOB access in font allocation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Commit 1a194e6c8e1e ("fbcon: fix integer overflow in fbcon_do_set_font") introduced an out-of-bounds access by storing data and allocation sizes in the same variable. Restore the old size calculation and use the new variable 'alloc_size' for the allocation. Signed-off-by: Thomas Zimmermann Fixes: 1a194e6c8e1e ("fbcon: fix integer overflow in fbcon_do_set_font") Reported-by: Jani Nikula Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15020 Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6201 Cc: Samasth Norway Ananda Cc: Thomas Zimmermann Cc: George Kennedy Cc: Greg Kroah-Hartman Cc: Simona Vetter Cc: Helge Deller Cc: "Ville Syrjälä" Cc: Sam Ravnborg Cc: Qianqiang Liu Cc: Shixiong Ou Cc: Kees Cook Cc: # v5.9+ Cc: Zsolt Kajtar Reviewed-by: Lucas De Marchi Reviewed-by: Qianqiang Liu Link: https://lore.kernel.org/r/20250922134619.257684-1-tzimmermann@suse.de --- drivers/video/fbdev/core/fbcon.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index a507d05f8feaa..5940e2eb92316 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2504,7 +2504,7 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font, unsigned charcount = font->charcount; int w = font->width; int h = font->height; - int size; + int size, alloc_size; int i, csum; u8 *new_data, *data = font->data; int pitch = PITCH(font->width); @@ -2537,10 +2537,10 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font, return -EINVAL; /* Check for overflow in allocation size calculation */ - if (check_add_overflow(FONT_EXTRA_WORDS * sizeof(int), size, &size)) + if (check_add_overflow(FONT_EXTRA_WORDS * sizeof(int), size, &alloc_size)) return -EINVAL; - new_data = kmalloc(size, GFP_USER); + new_data = kmalloc(alloc_size, GFP_USER); if (!new_data) return -ENOMEM; -- 2.39.5