149 lines
4.7 KiB
Diff
149 lines
4.7 KiB
Diff
From: Michael Chang <mchang@suse.com>
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Date: Fri, 9 Apr 2021 19:58:24 +0800
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Subject: [PATCH] Allocate LVM metadata buffer from raw contents
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The size reserved for on disk LVM metadata area can be exceedingly large that
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may trigger out of memory error for allocating buffer based on it. Refine the
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buffer allocation to use size of raw LVM metadata contents and read them from
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within the metadata area as we only need to parse the JSON formatted contents
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rather than the entire metadata area. This reduced the size significantly and
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the likelihood to out of memory error.
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---
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grub-core/disk/lvm.c | 79 ++++++++++++++++++++++++--------------------
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1 file changed, 43 insertions(+), 36 deletions(-)
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diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c
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index 8257159b3..1d1a3dcad 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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@@ -140,9 +140,11 @@ grub_lvm_detect (grub_disk_t disk,
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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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+ grub_uint64_t mda_raw_offset, mda_raw_size;
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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 mdah_buf[sizeof (struct grub_lvm_mda_header) + sizeof (struct grub_lvm_raw_locn)];
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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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@@ -220,21 +222,15 @@ grub_lvm_detect (grub_disk_t disk,
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dlocn++;
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mda_offset = grub_le_to_cpu64 (dlocn->offset);
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- mda_size = grub_le_to_cpu64 (dlocn->size);
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/* It's possible to have multiple copies of metadata areas, we just use the
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first one. */
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-
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- /* Allocate buffer space for the circular worst-case scenario. */
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- metadatabuf = grub_calloc (2, mda_size);
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- if (! metadatabuf)
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+ err = grub_disk_read (disk, 0, mda_offset, sizeof (mdah_buf), mdah_buf);
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+ if (err)
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goto fail;
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- err = grub_disk_read (disk, 0, mda_offset, mda_size, metadatabuf);
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- if (err)
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- goto fail2;
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+ mdah = (struct grub_lvm_mda_header *) mdah_buf;
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- mdah = (struct grub_lvm_mda_header *) metadatabuf;
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if ((grub_strncmp ((char *)mdah->magic, GRUB_LVM_FMTT_MAGIC,
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sizeof (mdah->magic)))
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|| (grub_le_to_cpu32 (mdah->version) != GRUB_LVM_FMTT_VERSION))
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@@ -244,42 +240,58 @@ grub_lvm_detect (grub_disk_t disk,
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#ifdef GRUB_UTIL
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grub_util_info ("unknown LVM metadata header");
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#endif
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- goto fail2;
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+ goto fail;
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}
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rlocn = mdah->raw_locns;
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- if (grub_le_to_cpu64 (rlocn->offset) >= grub_le_to_cpu64 (mda_size))
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+
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+ mda_size = grub_le_to_cpu64 (mdah->size);
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+ mda_raw_size = grub_le_to_cpu64 (rlocn->size);
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+ mda_raw_offset = grub_le_to_cpu64 (rlocn->offset);
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+
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+ if (mda_raw_offset >= mda_size)
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{
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#ifdef GRUB_UTIL
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grub_util_info ("metadata offset is beyond end of metadata area");
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#endif
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- goto fail2;
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+ goto fail;
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}
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- if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) >
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- grub_le_to_cpu64 (mdah->size))
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+ metadatabuf = grub_malloc (mda_raw_size);
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+
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+ if (! metadatabuf)
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+ goto fail;
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+
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+ if (mda_raw_offset + mda_raw_size > mda_size)
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{
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- if (2 * mda_size < GRUB_LVM_MDA_HEADER_SIZE ||
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- (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) -
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- grub_le_to_cpu64 (mdah->size) > mda_size - GRUB_LVM_MDA_HEADER_SIZE))
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- {
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-#ifdef GRUB_UTIL
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- grub_util_info ("cannot copy metadata wrap in circular buffer");
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-#endif
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- goto fail2;
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- }
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+ err = grub_disk_read (disk, 0,
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+ mda_offset + mda_raw_offset,
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+ mda_size - mda_raw_offset,
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+ metadatabuf);
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+ if (err)
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+ goto fail2;
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/* Metadata is circular. Copy the wrap in place. */
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- grub_memcpy (metadatabuf + mda_size,
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- metadatabuf + GRUB_LVM_MDA_HEADER_SIZE,
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- grub_le_to_cpu64 (rlocn->offset) +
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- grub_le_to_cpu64 (rlocn->size) -
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- grub_le_to_cpu64 (mdah->size));
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+ err = grub_disk_read (disk, 0,
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+ mda_offset + GRUB_LVM_MDA_HEADER_SIZE,
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+ mda_raw_offset + mda_raw_size - mda_size,
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+ metadatabuf + mda_size - mda_raw_offset);
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+ if (err)
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+ goto fail2;
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+ }
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+ else
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+ {
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+ err = grub_disk_read (disk, 0,
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+ mda_offset + mda_raw_offset,
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+ mda_raw_size,
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+ metadatabuf);
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+ if (err)
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+ goto fail2;
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}
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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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+ p = q = metadatabuf;
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+
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+ if (grub_add ((grub_size_t)metadatabuf, (grub_size_t)mda_raw_size, &ptr))
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{
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error_parsing_metadata:
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#ifdef GRUB_UTIL
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@@ -288,11 +300,6 @@ grub_lvm_detect (grub_disk_t disk,
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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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while (*q != ' ' && q < mda_end)
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