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kumquat-buildroot/boot/grub2/0024-efi-Fix-some-malformed-device-path-arithmetic-errors.patch
Stefan Sørensen 2f7a8021b5 boot/grub2: Backport Boothole securify fixes 
Details: https://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html

Fixes the following security issues:

 * CVE-2020-10713
   A flaw was found in grub2, prior to version 2.06. An attacker may
   use the GRUB 2 flaw to hijack and tamper the GRUB verification
   process. This flaw also allows the bypass of Secure Boot
   protections. In order to load an untrusted or modified kernel, an
   attacker would first need to establish access to the system such as
   gaining physical access, obtain the ability to alter a pxe-boot
   network, or have remote access to a networked system with root
   access. With this access, an attacker could then craft a string to
   cause a buffer overflow by injecting a malicious payload that leads
   to arbitrary code execution within GRUB. The highest threat from
   this vulnerability is to data confidentiality and integrity as well
   as system availability.

 * CVE-2020-14308
   In grub2 versions before 2.06 the grub memory allocator doesn't
   check for possible arithmetic overflows on the requested allocation
   size. This leads the function to return invalid memory allocations
   which can be further used to cause possible integrity,
   confidentiality and availability impacts during the boot process.

 * CVE-2020-14309
   There's an issue with grub2 in all versions before 2.06 when
   handling squashfs filesystems containing a symbolic link with name
   length of UINT32 bytes in size. The name size leads to an
   arithmetic overflow leading to a zero-size allocation further
   causing a heap-based buffer overflow with attacker controlled data.

 * CVE-2020-14310
   An integer overflow in read_section_from_string may lead to a heap
   based buffer overflow.

 * CVE-2020-14311
   An integer overflow in grub_ext2_read_link may lead to a heap-based
   buffer overflow.

 * CVE-2020-15706
   GRUB2 contains a race condition in grub_script_function_create()
   leading to a use-after-free vulnerability which can be triggered by
   redefining a function whilst the same function is already
   executing, leading to arbitrary code execution and secure boot
   restriction bypass

 * CVE-2020-15707
   Integer overflows were discovered in the functions grub_cmd_initrd
   and grub_initrd_init in the efilinux component of GRUB2, as shipped
   in Debian, Red Hat, and Ubuntu (the functionality is not included
   in GRUB2 upstream), leading to a heap-based buffer overflow. These
   could be triggered by an extremely large number of arguments to the
   initrd command on 32-bit architectures, or a crafted filesystem
   with very large files on any architecture. An attacker could use
   this to execute arbitrary code and bypass UEFI Secure Boot
   restrictions. This issue affects GRUB2 version 2.04 and prior
   versions.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2020-08-03 13:38:49 +02:00

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From c330aa099a38bc5c4d3066954fe35767cc06adb1 Mon Sep 17 00:00:00 2001
From: Peter Jones <pjones@redhat.com>
Date: Sun, 19 Jul 2020 16:53:27 -0400
Subject: [PATCH] efi: Fix some malformed device path arithmetic errors
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Several places we take the length of a device path and subtract 4 from
it, without ever checking that it's >= 4. There are also cases where
this kind of malformation will result in unpredictable iteration,
including treating the length from one dp node as the type in the next
node. These are all errors, no matter where the data comes from.
This patch adds a checking macro, GRUB_EFI_DEVICE_PATH_VALID(), which
can be used in several places, and makes GRUB_EFI_NEXT_DEVICE_PATH()
return NULL and GRUB_EFI_END_ENTIRE_DEVICE_PATH() evaluate as true when
the length is too small. Additionally, it makes several places in the
code check for and return errors in these cases.
Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
---
grub-core/kern/efi/efi.c | 64 +++++++++++++++++++++++++-----
grub-core/loader/efi/chainloader.c | 13 +++++-
grub-core/loader/i386/xnu.c | 9 +++--
include/grub/efi/api.h | 14 ++++---
4 files changed, 79 insertions(+), 21 deletions(-)
diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
index dc31caa21..c97969a65 100644
--- a/grub-core/kern/efi/efi.c
+++ b/grub-core/kern/efi/efi.c
@@ -332,7 +332,7 @@ grub_efi_get_filename (grub_efi_device_path_t *dp0)
dp = dp0;
- while (1)
+ while (dp)
{
grub_efi_uint8_t type = GRUB_EFI_DEVICE_PATH_TYPE (dp);
grub_efi_uint8_t subtype = GRUB_EFI_DEVICE_PATH_SUBTYPE (dp);
@@ -342,9 +342,15 @@ grub_efi_get_filename (grub_efi_device_path_t *dp0)
if (type == GRUB_EFI_MEDIA_DEVICE_PATH_TYPE
&& subtype == GRUB_EFI_FILE_PATH_DEVICE_PATH_SUBTYPE)
{
- grub_efi_uint16_t len;
- len = ((GRUB_EFI_DEVICE_PATH_LENGTH (dp) - 4)
- / sizeof (grub_efi_char16_t));
+ grub_efi_uint16_t len = GRUB_EFI_DEVICE_PATH_LENGTH (dp);
+
+ if (len < 4)
+ {
+ grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "malformed EFI Device Path node has length=%d", len);
+ return NULL;
+ }
+ len = (len - 4) / sizeof (grub_efi_char16_t);
filesize += GRUB_MAX_UTF8_PER_UTF16 * len + 2;
}
@@ -360,7 +366,7 @@ grub_efi_get_filename (grub_efi_device_path_t *dp0)
if (!name)
return NULL;
- while (1)
+ while (dp)
{
grub_efi_uint8_t type = GRUB_EFI_DEVICE_PATH_TYPE (dp);
grub_efi_uint8_t subtype = GRUB_EFI_DEVICE_PATH_SUBTYPE (dp);
@@ -376,8 +382,15 @@ grub_efi_get_filename (grub_efi_device_path_t *dp0)
*p++ = '/';
- len = ((GRUB_EFI_DEVICE_PATH_LENGTH (dp) - 4)
- / sizeof (grub_efi_char16_t));
+ len = GRUB_EFI_DEVICE_PATH_LENGTH (dp);
+ if (len < 4)
+ {
+ grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "malformed EFI Device Path node has length=%d", len);
+ return NULL;
+ }
+
+ len = (len - 4) / sizeof (grub_efi_char16_t);
fp = (grub_efi_file_path_device_path_t *) dp;
/* According to EFI spec Path Name is NULL terminated */
while (len > 0 && fp->path_name[len - 1] == 0)
@@ -452,7 +465,26 @@ grub_efi_duplicate_device_path (const grub_efi_device_path_t *dp)
;
p = GRUB_EFI_NEXT_DEVICE_PATH (p))
{
- total_size += GRUB_EFI_DEVICE_PATH_LENGTH (p);
+ grub_size_t len = GRUB_EFI_DEVICE_PATH_LENGTH (p);
+
+ /*
+ * In the event that we find a node that's completely garbage, for
+ * example if we get to 0x7f 0x01 0x02 0x00 ... (EndInstance with a size
+ * of 2), GRUB_EFI_END_ENTIRE_DEVICE_PATH() will be true and
+ * GRUB_EFI_NEXT_DEVICE_PATH() will return NULL, so we won't continue,
+ * and neither should our consumers, but there won't be any error raised
+ * even though the device path is junk.
+ *
+ * This keeps us from passing junk down back to our caller.
+ */
+ if (len < 4)
+ {
+ grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "malformed EFI Device Path node has length=%d", len);
+ return NULL;
+ }
+
+ total_size += len;
if (GRUB_EFI_END_ENTIRE_DEVICE_PATH (p))
break;
}
@@ -497,7 +529,7 @@ dump_vendor_path (const char *type, grub_efi_vendor_device_path_t *vendor)
void
grub_efi_print_device_path (grub_efi_device_path_t *dp)
{
- while (1)
+ while (GRUB_EFI_DEVICE_PATH_VALID (dp))
{
grub_efi_uint8_t type = GRUB_EFI_DEVICE_PATH_TYPE (dp);
grub_efi_uint8_t subtype = GRUB_EFI_DEVICE_PATH_SUBTYPE (dp);
@@ -909,7 +941,10 @@ grub_efi_compare_device_paths (const grub_efi_device_path_t *dp1,
/* Return non-zero. */
return 1;
- while (1)
+ if (dp1 == dp2)
+ return 0;
+
+ while (GRUB_EFI_DEVICE_PATH_VALID (dp1) && GRUB_EFI_DEVICE_PATH_VALID (dp2))
{
grub_efi_uint8_t type1, type2;
grub_efi_uint8_t subtype1, subtype2;
@@ -945,5 +980,14 @@ grub_efi_compare_device_paths (const grub_efi_device_path_t *dp1,
dp2 = (grub_efi_device_path_t *) ((char *) dp2 + len2);
}
+ /*
+ * There's no "right" answer here, but we probably don't want to call a valid
+ * dp and an invalid dp equal, so pick one way or the other.
+ */
+ if (GRUB_EFI_DEVICE_PATH_VALID (dp1) && !GRUB_EFI_DEVICE_PATH_VALID (dp2))
+ return 1;
+ else if (!GRUB_EFI_DEVICE_PATH_VALID (dp1) && GRUB_EFI_DEVICE_PATH_VALID (dp2))
+ return -1;
+
return 0;
}
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
index daf8c6b54..a8d7b9155 100644
--- a/grub-core/loader/efi/chainloader.c
+++ b/grub-core/loader/efi/chainloader.c
@@ -156,9 +156,18 @@ make_file_path (grub_efi_device_path_t *dp, const char *filename)
size = 0;
d = dp;
- while (1)
+ while (d)
{
- size += GRUB_EFI_DEVICE_PATH_LENGTH (d);
+ grub_size_t len = GRUB_EFI_DEVICE_PATH_LENGTH (d);
+
+ if (len < 4)
+ {
+ grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "malformed EFI Device Path node has length=%d", len);
+ return NULL;
+ }
+
+ size += len;
if ((GRUB_EFI_END_ENTIRE_DEVICE_PATH (d)))
break;
d = GRUB_EFI_NEXT_DEVICE_PATH (d);
diff --git a/grub-core/loader/i386/xnu.c b/grub-core/loader/i386/xnu.c
index e9e119259..a70093607 100644
--- a/grub-core/loader/i386/xnu.c
+++ b/grub-core/loader/i386/xnu.c
@@ -515,14 +515,15 @@ grub_cmd_devprop_load (grub_command_t cmd __attribute__ ((unused)),
devhead = buf;
buf = devhead + 1;
- dpstart = buf;
+ dp = dpstart = buf;
- do
+ while (GRUB_EFI_DEVICE_PATH_VALID (dp) && buf < bufend)
{
- dp = buf;
buf = (char *) buf + GRUB_EFI_DEVICE_PATH_LENGTH (dp);
+ if (GRUB_EFI_END_ENTIRE_DEVICE_PATH (dp))
+ break;
+ dp = buf;
}
- while (!GRUB_EFI_END_ENTIRE_DEVICE_PATH (dp) && buf < bufend);
dev = grub_xnu_devprop_add_device (dpstart, (char *) buf
- (char *) dpstart);
diff --git a/include/grub/efi/api.h b/include/grub/efi/api.h
index addcbfa8f..cf1355a8c 100644
--- a/include/grub/efi/api.h
+++ b/include/grub/efi/api.h
@@ -625,6 +625,7 @@ typedef struct grub_efi_device_path grub_efi_device_path_protocol_t;
#define GRUB_EFI_DEVICE_PATH_TYPE(dp) ((dp)->type & 0x7f)
#define GRUB_EFI_DEVICE_PATH_SUBTYPE(dp) ((dp)->subtype)
#define GRUB_EFI_DEVICE_PATH_LENGTH(dp) ((dp)->length)
+#define GRUB_EFI_DEVICE_PATH_VALID(dp) ((dp) != NULL && GRUB_EFI_DEVICE_PATH_LENGTH (dp) >= 4)
/* The End of Device Path nodes. */
#define GRUB_EFI_END_DEVICE_PATH_TYPE (0xff & 0x7f)
@@ -633,13 +634,16 @@ typedef struct grub_efi_device_path grub_efi_device_path_protocol_t;
#define GRUB_EFI_END_THIS_DEVICE_PATH_SUBTYPE 0x01
#define GRUB_EFI_END_ENTIRE_DEVICE_PATH(dp) \
- (GRUB_EFI_DEVICE_PATH_TYPE (dp) == GRUB_EFI_END_DEVICE_PATH_TYPE \
- && (GRUB_EFI_DEVICE_PATH_SUBTYPE (dp) \
- == GRUB_EFI_END_ENTIRE_DEVICE_PATH_SUBTYPE))
+ (!GRUB_EFI_DEVICE_PATH_VALID (dp) || \
+ (GRUB_EFI_DEVICE_PATH_TYPE (dp) == GRUB_EFI_END_DEVICE_PATH_TYPE \
+ && (GRUB_EFI_DEVICE_PATH_SUBTYPE (dp) \
+ == GRUB_EFI_END_ENTIRE_DEVICE_PATH_SUBTYPE)))
#define GRUB_EFI_NEXT_DEVICE_PATH(dp) \
- ((grub_efi_device_path_t *) ((char *) (dp) \
- + GRUB_EFI_DEVICE_PATH_LENGTH (dp)))
+ (GRUB_EFI_DEVICE_PATH_VALID (dp) \
+ ? ((grub_efi_device_path_t *) \
+ ((char *) (dp) + GRUB_EFI_DEVICE_PATH_LENGTH (dp))) \
+ : NULL)
/* Hardware Device Path. */
#define GRUB_EFI_HARDWARE_DEVICE_PATH_TYPE 1
--
2.26.2
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