CVE-2026-74424fbcon: fix NULL pointer dereference for a console without vc_data

Official description

In the Linux kernel, the following vulnerability has been resolved: fbcon: fix NULL pointer dereference for a console without vc_data fbcon_new_modelist() runs when a framebuffer's modelist changes. For each console mapped to it with fb_display[i].mode set, it reads vc_cons[i].d and passes the vc_num to fbcon_set_disp(). This assumes a console with a mode set has a vc_data, but it can be NULL. fbcon_set_disp() sets fb_display[i].mode before it checks vc_data, and fbcon_deinit() leaves the mode set after the vc_data is freed. fbcon_new_modelist() then dereferences the NULL vc_data. Keep fb_display[i].mode set only while the console has a vc_data. Check vc_data before setting the mode in fbcon_set_disp(), and clear the mode in fbcon_deinit(). The existing mode check in fbcon_new_modelist() then skips such consoles.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/8e9b8b008f4036df0318870c5d754134ff1b94cc
• https://git.kernel.org/stable/c/cc4382dc5134826a3936a6b08de17f7dc7abe232
• https://git.kernel.org/stable/c/9b783b7e03dc78ec102edf618259a2b55911fc6a
• https://git.kernel.org/stable/c/ac970358c5ca0775841bd2a56ce15dc464b99003
• https://git.kernel.org/stable/c/6617df8c246311c82cebf061a4cee55b9df60922
• https://git.kernel.org/stable/c/b134ad2f7c06b3c1098dcc95008e2045ff4b49b2
• https://git.kernel.org/stable/c/5fae9a928482d4845bca169a3a098789203a1ca4