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From: Maxim Suhanov <dfirblog@gmail.com>
Date: Mon, 28 Aug 2023 16:33:44 +0300
Subject: fs/ntfs: Fix an OOB read when parsing bitmaps for index attributes
This fix introduces checks to ensure that bitmaps for directory indices
are never read beyond their actual sizes.
The lack of this check is a minor issue, likely not exploitable in any way.
Reported-by: Maxim Suhanov <dfirblog@gmail.com>
Signed-off-by: Maxim Suhanov <dfirblog@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/fs/ntfs.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/grub-core/fs/ntfs.c b/grub-core/fs/ntfs.c
index 2d78b96..bb70c89 100644
--- a/grub-core/fs/ntfs.c
+++ b/grub-core/fs/ntfs.c
@@ -843,6 +843,25 @@ grub_ntfs_iterate_dir (grub_fshelp_node_t dir,
if (is_resident)
{
+ if (bitmap_len > (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "resident bitmap too large");
+ goto done;
+ }
+
+ if (cur_pos >= at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "resident bitmap out of range");
+ goto done;
+ }
+
+ if (u16at (cur_pos, 0x14) + u32at (cur_pos, 0x10) >
+ (grub_addr_t) at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR) - (grub_addr_t) cur_pos)
+ {
+ grub_error (GRUB_ERR_BAD_FS, "resident bitmap out of range");
+ goto done;
+ }
+
grub_memcpy (bmp, cur_pos + u16at (cur_pos, 0x14),
bitmap_len);
}
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