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62 lines
2.0 KiB
62 lines
2.0 KiB
9 months ago
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From 1fe82c41e070385e273d7bb1cfb482627a3c28e8 Mon Sep 17 00:00:00 2001
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From: Maxim Suhanov <dfirblog@gmail.com>
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Date: Mon, 28 Aug 2023 16:38:19 +0300
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Subject: [PATCH 5/6] fs/ntfs: Fix an OOB read when parsing a volume label
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This fix introduces checks to ensure that an NTFS volume label is always
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read from the corresponding file record segment.
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The current NTFS code allows the volume label string to be read from an
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arbitrary, attacker-chosen memory location. However, the bytes read are
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always treated as UTF-16LE. So, the final string displayed is mostly
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unreadable and it can't be easily converted back to raw bytes.
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The lack of this check is a minor issue, likely not causing a significant
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data leak.
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Reported-by: Maxim Suhanov <dfirblog@gmail.com>
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Signed-off-by: Maxim Suhanov <dfirblog@gmail.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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grub-core/fs/ntfs.c | 18 +++++++++++++++++-
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1 file changed, 17 insertions(+), 1 deletion(-)
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diff --git a/grub-core/fs/ntfs.c b/grub-core/fs/ntfs.c
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index bb70c89fb803..ff5e3740f0dd 100644
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--- a/grub-core/fs/ntfs.c
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+++ b/grub-core/fs/ntfs.c
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@@ -1213,13 +1213,29 @@ grub_ntfs_label (grub_device_t device, char **label)
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init_attr (&mft->attr, mft);
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pa = find_attr (&mft->attr, GRUB_NTFS_AT_VOLUME_NAME);
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+
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+ if (pa >= mft->buf + (mft->data->mft_size << GRUB_NTFS_BLK_SHR))
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+ {
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+ grub_error (GRUB_ERR_BAD_FS, "can\'t parse volume label");
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+ goto fail;
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+ }
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+
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+ if (mft->buf + (mft->data->mft_size << GRUB_NTFS_BLK_SHR) - pa < 0x16)
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+ {
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+ grub_error (GRUB_ERR_BAD_FS, "can\'t parse volume label");
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+ goto fail;
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+ }
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+
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if ((pa) && (pa[8] == 0) && (u32at (pa, 0x10)))
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{
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int len;
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len = u32at (pa, 0x10) / 2;
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pa += u16at (pa, 0x14);
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- *label = get_utf8 (pa, len);
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+ if (mft->buf + (mft->data->mft_size << GRUB_NTFS_BLK_SHR) - pa >= 2 * len)
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+ *label = get_utf8 (pa, len);
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+ else
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+ grub_error (GRUB_ERR_BAD_FS, "can\'t parse volume label");
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}
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fail:
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--
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2.43.0
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