2f7a8021b5
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>
117 lines
3.4 KiB
Diff
117 lines
3.4 KiB
Diff
From a1845e90fc19fb5e904091bad8a378f458798e4a Mon Sep 17 00:00:00 2001
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From: Peter Jones <pjones@redhat.com>
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Date: Sun, 19 Jul 2020 15:48:20 -0400
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Subject: [PATCH] lvm: Fix two more potential data-dependent alloc
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overflows
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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It appears to be possible to make a (possibly invalid) lvm PV with
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a metadata size field that overflows our type when adding it to the
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address we've allocated. Even if it doesn't, it may be possible to do so
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with the math using the outcome of that as an operand. Check them both.
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Signed-off-by: Peter Jones <pjones@redhat.com>
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Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
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---
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grub-core/disk/lvm.c | 48 ++++++++++++++++++++++++++++++++++++--------
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1 file changed, 40 insertions(+), 8 deletions(-)
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diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c
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index d1df640b3..139fafd47 100644
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--- a/grub-core/disk/lvm.c
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+++ b/grub-core/disk/lvm.c
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@@ -25,6 +25,7 @@
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#include <grub/lvm.h>
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#include <grub/partition.h>
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#include <grub/i18n.h>
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+#include <grub/safemath.h>
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#ifdef GRUB_UTIL
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#include <grub/emu/misc.h>
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@@ -102,10 +103,11 @@ grub_lvm_detect (grub_disk_t disk,
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{
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grub_err_t err;
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grub_uint64_t mda_offset, mda_size;
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+ grub_size_t ptr;
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char buf[GRUB_LVM_LABEL_SIZE];
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char vg_id[GRUB_LVM_ID_STRLEN+1];
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char pv_id[GRUB_LVM_ID_STRLEN+1];
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- char *metadatabuf, *p, *q, *vgname;
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+ char *metadatabuf, *p, *q, *mda_end, *vgname;
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struct grub_lvm_label_header *lh = (struct grub_lvm_label_header *) buf;
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struct grub_lvm_pv_header *pvh;
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struct grub_lvm_disk_locn *dlocn;
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@@ -205,19 +207,31 @@ grub_lvm_detect (grub_disk_t disk,
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grub_le_to_cpu64 (rlocn->size) -
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grub_le_to_cpu64 (mdah->size));
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}
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- p = q = metadatabuf + grub_le_to_cpu64 (rlocn->offset);
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- while (*q != ' ' && q < metadatabuf + mda_size)
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- q++;
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-
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- if (q == metadatabuf + mda_size)
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+ if (grub_add ((grub_size_t)metadatabuf,
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+ (grub_size_t)grub_le_to_cpu64 (rlocn->offset),
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+ &ptr))
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{
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+ error_parsing_metadata:
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#ifdef GRUB_UTIL
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grub_util_info ("error parsing metadata");
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#endif
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goto fail2;
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}
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+ p = q = (char *)ptr;
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+
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+ if (grub_add ((grub_size_t)metadatabuf, (grub_size_t)mda_size, &ptr))
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+ goto error_parsing_metadata;
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+
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+ mda_end = (char *)ptr;
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+
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+ while (*q != ' ' && q < mda_end)
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+ q++;
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+
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+ if (q == mda_end)
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+ goto error_parsing_metadata;
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+
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vgname_len = q - p;
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vgname = grub_malloc (vgname_len + 1);
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if (!vgname)
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@@ -367,8 +381,26 @@ grub_lvm_detect (grub_disk_t disk,
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{
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const char *iptr;
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char *optr;
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- lv->fullname = grub_malloc (sizeof ("lvm/") - 1 + 2 * vgname_len
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- + 1 + 2 * s + 1);
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+
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+ /*
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+ * This is kind of hard to read with our safe (but rather
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+ * baroque) math primatives, but it boils down to:
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+ *
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+ * sz0 = vgname_len * 2 + 1 +
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+ * s * 2 + 1 +
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+ * sizeof ("lvm/") - 1;
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+ */
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+ grub_size_t sz0 = vgname_len, sz1 = s;
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+
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+ if (grub_mul (sz0, 2, &sz0) ||
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+ grub_add (sz0, 1, &sz0) ||
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+ grub_mul (sz1, 2, &sz1) ||
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+ grub_add (sz1, 1, &sz1) ||
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+ grub_add (sz0, sz1, &sz0) ||
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+ grub_add (sz0, sizeof ("lvm/") - 1, &sz0))
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+ goto lvs_fail;
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+
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+ lv->fullname = grub_malloc (sz0);
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if (!lv->fullname)
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goto lvs_fail;
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--
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2.26.2
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