From: Greg Kroah-Hartman Date: Mon, 9 Nov 2020 10:02:15 +0000 (+0100) Subject: 5.4-stable patches X-Git-Tag: v4.4.242~14 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6e8fe4fc72dc46ed169443488ddf9a414a59e419;p=thirdparty%2Fkernel%2Fstable-queue.git 5.4-stable patches added patches: vt-disable-kd_font_op_copy.patch --- diff --git a/queue-5.4/series b/queue-5.4/series index 4d18121499a..85da4f514e0 100644 --- a/queue-5.4/series +++ b/queue-5.4/series @@ -61,3 +61,4 @@ drm-nouveau-nouveau-fix-the-start-end-range-for-migr.patch drm-nouveau-gem-fix-refcount_t-underflow-use-after-f.patch arm64-smp-move-rcu_cpu_starting-earlier.patch revert-coresight-make-sysfs-functional-on-topologies.patch +vt-disable-kd_font_op_copy.patch diff --git a/queue-5.4/vt-disable-kd_font_op_copy.patch b/queue-5.4/vt-disable-kd_font_op_copy.patch new file mode 100644 index 00000000000..3011b5297f7 --- /dev/null +++ b/queue-5.4/vt-disable-kd_font_op_copy.patch @@ -0,0 +1,117 @@ +From 3c4e0dff2095c579b142d5a0693257f1c58b4804 Mon Sep 17 00:00:00 2001 +From: Daniel Vetter +Date: Sun, 8 Nov 2020 16:38:06 +0100 +Subject: vt: Disable KD_FONT_OP_COPY + +From: Daniel Vetter + +commit 3c4e0dff2095c579b142d5a0693257f1c58b4804 upstream. + +It's buggy: + +On Fri, Nov 06, 2020 at 10:30:08PM +0800, Minh Yuan wrote: +> We recently discovered a slab-out-of-bounds read in fbcon in the latest +> kernel ( v5.10-rc2 for now ). The root cause of this vulnerability is that +> "fbcon_do_set_font" did not handle "vc->vc_font.data" and +> "vc->vc_font.height" correctly, and the patch +> for VT_RESIZEX can't handle this +> issue. +> +> Specifically, we use KD_FONT_OP_SET to set a small font.data for tty6, and +> use KD_FONT_OP_SET again to set a large font.height for tty1. After that, +> we use KD_FONT_OP_COPY to assign tty6's vc_font.data to tty1's vc_font.data +> in "fbcon_do_set_font", while tty1 retains the original larger +> height. Obviously, this will cause an out-of-bounds read, because we can +> access a smaller vc_font.data with a larger vc_font.height. + +Further there was only one user ever. +- Android's loadfont, busybox and console-tools only ever use OP_GET + and OP_SET +- fbset documentation only mentions the kernel cmdline font: option, + not anything else. +- systemd used OP_COPY before release 232 published in Nov 2016 + +Now unfortunately the crucial report seems to have gone down with +gmane, and the commit message doesn't say much. But the pull request +hints at OP_COPY being broken + +https://github.com/systemd/systemd/pull/3651 + +So in other words, this never worked, and the only project which +foolishly every tried to use it, realized that rather quickly too. + +Instead of trying to fix security issues here on dead code by adding +missing checks, fix the entire thing by removing the functionality. + +Note that systemd code using the OP_COPY function ignored the return +value, so it doesn't matter what we're doing here really - just in +case a lone server somewhere happens to be extremely unlucky and +running an affected old version of systemd. The relevant code from +font_copy_to_all_vcs() in systemd was: + + /* copy font from active VT, where the font was uploaded to */ + cfo.op = KD_FONT_OP_COPY; + cfo.height = vcs.v_active-1; /* tty1 == index 0 */ + (void) ioctl(vcfd, KDFONTOP, &cfo); + +Note this just disables the ioctl, garbage collecting the now unused +callbacks is left for -next. + +v2: Tetsuo found the old mail, which allowed me to find it on another +archive. Add the link too. + +Acked-by: Peilin Ye +Reported-by: Minh Yuan +References: https://lists.freedesktop.org/archives/systemd-devel/2016-June/036935.html +References: https://github.com/systemd/systemd/pull/3651 +Cc: Greg KH +Cc: Peilin Ye +Cc: Tetsuo Handa +Signed-off-by: Daniel Vetter +Link: https://lore.kernel.org/r/20201108153806.3140315-1-daniel.vetter@ffwll.ch +Signed-off-by: Greg Kroah-Hartman + +--- + drivers/tty/vt/vt.c | 24 ++---------------------- + 1 file changed, 2 insertions(+), 22 deletions(-) + +--- a/drivers/tty/vt/vt.c ++++ b/drivers/tty/vt/vt.c +@@ -4620,27 +4620,6 @@ static int con_font_default(struct vc_da + return rc; + } + +-static int con_font_copy(struct vc_data *vc, struct console_font_op *op) +-{ +- int con = op->height; +- int rc; +- +- +- console_lock(); +- if (vc->vc_mode != KD_TEXT) +- rc = -EINVAL; +- else if (!vc->vc_sw->con_font_copy) +- rc = -ENOSYS; +- else if (con < 0 || !vc_cons_allocated(con)) +- rc = -ENOTTY; +- else if (con == vc->vc_num) /* nothing to do */ +- rc = 0; +- else +- rc = vc->vc_sw->con_font_copy(vc, con); +- console_unlock(); +- return rc; +-} +- + int con_font_op(struct vc_data *vc, struct console_font_op *op) + { + switch (op->op) { +@@ -4651,7 +4630,8 @@ int con_font_op(struct vc_data *vc, stru + case KD_FONT_OP_SET_DEFAULT: + return con_font_default(vc, op); + case KD_FONT_OP_COPY: +- return con_font_copy(vc, op); ++ /* was buggy and never really used */ ++ return -EINVAL; + } + return -ENOSYS; + }