--- /dev/null
+From 1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe Mon Sep 17 00:00:00 2001
+From: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
+Date: Fri, 12 Sep 2025 10:00:23 -0700
+Subject: fbcon: fix integer overflow in fbcon_do_set_font
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
+
+commit 1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe upstream.
+
+Fix integer overflow vulnerabilities in fbcon_do_set_font() where font
+size calculations could overflow when handling user-controlled font
+parameters.
+
+The vulnerabilities occur when:
+1. CALC_FONTSZ(h, pitch, charcount) performs h * pith * charcount
+ multiplication with user-controlled values that can overflow.
+2. FONT_EXTRA_WORDS * sizeof(int) + size addition can also overflow
+3. This results in smaller allocations than expected, leading to buffer
+ overflows during font data copying.
+
+Add explicit overflow checking using check_mul_overflow() and
+check_add_overflow() kernel helpers to safety validate all size
+calculations before allocation.
+
+Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
+Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
+Fixes: 39b3cffb8cf3 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access")
+Cc: George Kennedy <george.kennedy@oracle.com>
+Cc: stable <stable@vger.kernel.org>
+Cc: syzbot+38a3699c7eaf165b97a6@syzkaller.appspotmail.com
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Cc: Simona Vetter <simona@ffwll.ch>
+Cc: Helge Deller <deller@gmx.de>
+Cc: Thomas Zimmermann <tzimmermann@suse.de>
+Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
+Cc: Sam Ravnborg <sam@ravnborg.org>
+Cc: Qianqiang Liu <qianqiang.liu@163.com>
+Cc: Shixiong Ou <oushixiong@kylinos.cn>
+Cc: Kees Cook <kees@kernel.org>
+Cc: <stable@vger.kernel.org> # v5.9+
+Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
+Link: https://lore.kernel.org/r/20250912170023.3931881-1-samasth.norway.ananda@oracle.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/video/fbdev/core/fbcon.c | 11 +++++++++--
+ 1 file changed, 9 insertions(+), 2 deletions(-)
+
+--- a/drivers/video/fbdev/core/fbcon.c
++++ b/drivers/video/fbdev/core/fbcon.c
+@@ -2527,9 +2527,16 @@ static int fbcon_set_font(struct vc_data
+ if (fbcon_invalid_charcount(info, charcount))
+ return -EINVAL;
+
+- size = CALC_FONTSZ(h, pitch, charcount);
++ /* Check for integer overflow in font size calculation */
++ if (check_mul_overflow(h, pitch, &size) ||
++ check_mul_overflow(size, charcount, &size))
++ return -EINVAL;
++
++ /* Check for overflow in allocation size calculation */
++ if (check_add_overflow(FONT_EXTRA_WORDS * sizeof(int), size, &size))
++ return -EINVAL;
+
+- new_data = kmalloc(FONT_EXTRA_WORDS * sizeof(int) + size, GFP_USER);
++ new_data = kmalloc(size, GFP_USER);
+
+ if (!new_data)
+ return -ENOMEM;
--- /dev/null
+From 9b2f5ef00e852f8e8902a4d4f73aeedc60220c12 Mon Sep 17 00:00:00 2001
+From: Thomas Zimmermann <tzimmermann@suse.de>
+Date: Mon, 22 Sep 2025 15:45:54 +0200
+Subject: fbcon: Fix OOB access in font allocation
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Thomas Zimmermann <tzimmermann@suse.de>
+
+commit 9b2f5ef00e852f8e8902a4d4f73aeedc60220c12 upstream.
+
+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 <tzimmermann@suse.de>
+Fixes: 1a194e6c8e1e ("fbcon: fix integer overflow in fbcon_do_set_font")
+Reported-by: Jani Nikula <jani.nikula@linux.intel.com>
+Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15020
+Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6201
+Cc: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
+Cc: Thomas Zimmermann <tzimmermann@suse.de>
+Cc: George Kennedy <george.kennedy@oracle.com>
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Cc: Simona Vetter <simona@ffwll.ch>
+Cc: Helge Deller <deller@gmx.de>
+Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
+Cc: Sam Ravnborg <sam@ravnborg.org>
+Cc: Qianqiang Liu <qianqiang.liu@163.com>
+Cc: Shixiong Ou <oushixiong@kylinos.cn>
+Cc: Kees Cook <kees@kernel.org>
+Cc: <stable@vger.kernel.org> # v5.9+
+Cc: Zsolt Kajtar <soci@c64.rulez.org>
+Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
+Reviewed-by: Qianqiang Liu <qianqiang.liu@163.com>
+Link: https://lore.kernel.org/r/20250922134619.257684-1-tzimmermann@suse.de
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/video/fbdev/core/fbcon.c | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+--- a/drivers/video/fbdev/core/fbcon.c
++++ b/drivers/video/fbdev/core/fbcon.c
+@@ -2500,7 +2500,7 @@ static int fbcon_set_font(struct vc_data
+ 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);
+@@ -2533,10 +2533,10 @@ static int fbcon_set_font(struct vc_data
+ 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;
projects / thirdparty / kernel / stable-queue.git / commitdiff
