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From 6993cce7c3a9d15e6573845f455d2f0de424a717 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Wed, 24 Feb 2021 15:03:26 +0100
Subject: [PATCH] gdb: Restrict GDB access when locked down
The gdbstub* commands allow to start and control a GDB stub running on
local host that can be used to connect from a remote debugger. Restrict
this functionality when the GRUB is locked down.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=508270838998f151a82e9c13e7cb8a470a2dc23d]
CVE: CVE-2020-27779
Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
---
grub-core/gdb/gdb.c | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)
diff --git a/grub-core/gdb/gdb.c b/grub-core/gdb/gdb.c
index 847a1e1..1818cb6 100644
--- a/grub-core/gdb/gdb.c
+++ b/grub-core/gdb/gdb.c
@@ -75,20 +75,24 @@ static grub_command_t cmd, cmd_stop, cmd_break;
GRUB_MOD_INIT (gdb)
{
grub_gdb_idtinit ();
- cmd = grub_register_command ("gdbstub", grub_cmd_gdbstub,
- N_("PORT"),
- /* TRANSLATORS: GDB stub is a small part of
- GDB functionality running on local host
- which allows remote debugger to
- connect to it. */
- N_("Start GDB stub on given port"));
- cmd_break = grub_register_command ("gdbstub_break", grub_cmd_gdb_break,
- /* TRANSLATORS: this refers to triggering
- a breakpoint so that the user will land
- into GDB. */
- 0, N_("Break into GDB"));
- cmd_stop = grub_register_command ("gdbstub_stop", grub_cmd_gdbstop,
- 0, N_("Stop GDB stub"));
+ cmd = grub_register_command_lockdown ("gdbstub", grub_cmd_gdbstub,
+ N_("PORT"),
+ /*
+ * TRANSLATORS: GDB stub is a small part of
+ * GDB functionality running on local host
+ * which allows remote debugger to
+ * connect to it.
+ */
+ N_("Start GDB stub on given port"));
+ cmd_break = grub_register_command_lockdown ("gdbstub_break", grub_cmd_gdb_break,
+ /*
+ * TRANSLATORS: this refers to triggering
+ * a breakpoint so that the user will land
+ * into GDB.
+ */
+ 0, N_("Break into GDB"));
+ cmd_stop = grub_register_command_lockdown ("gdbstub_stop", grub_cmd_gdbstop,
+ 0, N_("Stop GDB stub"));
}
GRUB_MOD_FINI (gdb)
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