From: Greg Kroah-Hartman Date: Wed, 28 Jan 2026 14:36:07 +0000 (+0100) Subject: 5.10-stable patches X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d6165603cd8a1bb7ced239f6ca9118d0e1181bf2;p=thirdparty%2Fkernel%2Fstable-queue.git 5.10-stable patches added patches: fbcon-always-restore-the-old-font-data-in-fbcon_do_set_font.patch --- diff --git a/queue-5.10/fbcon-always-restore-the-old-font-data-in-fbcon_do_set_font.patch b/queue-5.10/fbcon-always-restore-the-old-font-data-in-fbcon_do_set_font.patch new file mode 100644 index 0000000000..c64da77a49 --- /dev/null +++ b/queue-5.10/fbcon-always-restore-the-old-font-data-in-fbcon_do_set_font.patch @@ -0,0 +1,90 @@ +From 00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f Mon Sep 17 00:00:00 2001 +From: "Jiri Slaby (SUSE)" +Date: Thu, 8 Feb 2024 12:44:11 +0100 +Subject: fbcon: always restore the old font data in fbcon_do_set_font() + +From: Jiri Slaby (SUSE) + +commit 00d6a284fcf3fad1b7e1b5bc3cd87cbfb60ce03f upstream. + +Commit a5a923038d70 (fbdev: fbcon: Properly revert changes when +vc_resize() failed) started restoring old font data upon failure (of +vc_resize()). But it performs so only for user fonts. It means that the +"system"/internal fonts are not restored at all. So in result, the very +first call to fbcon_do_set_font() performs no restore at all upon +failing vc_resize(). + +This can be reproduced by Syzkaller to crash the system on the next +invocation of font_get(). It's rather hard to hit the allocation failure +in vc_resize() on the first font_set(), but not impossible. Esp. if +fault injection is used to aid the execution/failure. It was +demonstrated by Sirius: + BUG: unable to handle page fault for address: fffffffffffffff8 + #PF: supervisor read access in kernel mode + #PF: error_code(0x0000) - not-present page + PGD cb7b067 P4D cb7b067 PUD cb7d067 PMD 0 + Oops: 0000 [#1] PREEMPT SMP KASAN + CPU: 1 PID: 8007 Comm: poc Not tainted 6.7.0-g9d1694dc91ce #20 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 + RIP: 0010:fbcon_get_font+0x229/0x800 drivers/video/fbdev/core/fbcon.c:2286 + Call Trace: + + con_font_get drivers/tty/vt/vt.c:4558 [inline] + con_font_op+0x1fc/0xf20 drivers/tty/vt/vt.c:4673 + vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline] + vt_ioctl+0x632/0x2ec0 drivers/tty/vt/vt_ioctl.c:752 + tty_ioctl+0x6f8/0x1570 drivers/tty/tty_io.c:2803 + vfs_ioctl fs/ioctl.c:51 [inline] + ... + +So restore the font data in any case, not only for user fonts. Note the +later 'if' is now protected by 'old_userfont' and not 'old_data' as the +latter is always set now. (And it is supposed to be non-NULL. Otherwise +we would see the bug above again.) + +Signed-off-by: Jiri Slaby (SUSE) +Fixes: a5a923038d70 ("fbdev: fbcon: Properly revert changes when vc_resize() failed") +Reported-and-tested-by: Ubisectech Sirius +Cc: Ubisectech Sirius +Cc: Daniel Vetter +Cc: Helge Deller +Cc: linux-fbdev@vger.kernel.org +Cc: dri-devel@lists.freedesktop.org +Signed-off-by: Daniel Vetter +Link: https://patchwork.freedesktop.org/patch/msgid/20240208114411.14604-1-jirislaby@kernel.org +Signed-off-by: Greg Kroah-Hartman +--- + drivers/video/fbdev/core/fbcon.c | 8 +++----- + 1 file changed, 3 insertions(+), 5 deletions(-) + +--- a/drivers/video/fbdev/core/fbcon.c ++++ b/drivers/video/fbdev/core/fbcon.c +@@ -2425,11 +2425,9 @@ static int fbcon_do_set_font(struct vc_d + struct fbcon_ops *ops = info->fbcon_par; + struct fbcon_display *p = &fb_display[vc->vc_num]; + int resize, ret, old_userfont, old_width, old_height, old_charcount; +- char *old_data = NULL; ++ u8 *old_data = vc->vc_font.data; + + resize = (w != vc->vc_font.width) || (h != vc->vc_font.height); +- if (p->userfont) +- old_data = vc->vc_font.data; + vc->vc_font.data = (void *)(p->fontdata = data); + old_userfont = p->userfont; + if ((p->userfont = userfont)) +@@ -2463,13 +2461,13 @@ static int fbcon_do_set_font(struct vc_d + update_screen(vc); + } + +- if (old_data && (--REFCOUNT(old_data) == 0)) ++ if (old_userfont && (--REFCOUNT(old_data) == 0)) + kfree(old_data - FONT_EXTRA_WORDS * sizeof(int)); + return 0; + + err_out: + p->fontdata = old_data; +- vc->vc_font.data = (void *)old_data; ++ vc->vc_font.data = old_data; + + if (userfont) { + p->userfont = old_userfont; diff --git a/queue-5.10/series b/queue-5.10/series index c097040d8e..b0635d0755 100644 --- a/queue-5.10/series +++ b/queue-5.10/series @@ -117,3 +117,4 @@ bpf-do-not-let-bpf-test-infra-emit-invalid-gso-types-to-stack.patch bpf-reject-narrower-access-to-pointer-ctx-fields.patch fbdev-fbcon-properly-revert-changes-when-vc_resize-failed.patch fbdev-fbcon-release-buffer-when-fbcon_do_set_font-failed.patch +fbcon-always-restore-the-old-font-data-in-fbcon_do_set_font.patch