113 lines
3.2 KiB
Diff
113 lines
3.2 KiB
Diff
From 4a56a951ae3cc8ff25f94a291051b5246f1b828a 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 22/27] lvm: Fix two more potential data-dependent alloc
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overflows
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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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---
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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 8e76d1a..9f5630c 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, *vgname;
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+ char *metadatabuf, *mda_end, *vgname;
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const char *p, *q;
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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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@@ -206,19 +208,31 @@ 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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@@ -368,8 +382,26 @@ 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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2.23.0
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