91 lines
3.3 KiB
Diff
91 lines
3.3 KiB
Diff
From 0000000000000000000000000000000000000000 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 16:31:57 +0300
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Subject: [PATCH] fs/ntfs: Fix an OOB write when parsing the $ATTRIBUTE_LIST
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attribute for the $MFT file
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When parsing an extremely fragmented $MFT file, i.e., the file described
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using the $ATTRIBUTE_LIST attribute, current NTFS code will reuse a buffer
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containing bytes read from the underlying drive to store sector numbers,
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which are consumed later to read data from these sectors into another buffer.
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These sectors numbers, two 32-bit integers, are always stored at predefined
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offsets, 0x10 and 0x14, relative to first byte of the selected entry within
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the $ATTRIBUTE_LIST attribute. Usually, this won't cause any problem.
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However, when parsing a specially-crafted file system image, this may cause
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the NTFS code to write these integers beyond the buffer boundary, likely
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causing the GRUB memory allocator to misbehave or fail. These integers contain
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values which are controlled by on-disk structures of the NTFS file system.
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Such modification and resulting misbehavior may touch a memory range not
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assigned to the GRUB and owned by firmware or another EFI application/driver.
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This fix introduces checks to ensure that these sector numbers are never
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written beyond the boundary.
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Fixes: CVE-2023-4692
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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 3511e4e2cb6f..4681c7ac32a8 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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@@ -184,7 +184,7 @@ find_attr (struct grub_ntfs_attr *at, grub_uint8_t attr)
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}
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if (at->attr_end)
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{
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- grub_uint8_t *pa;
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+ grub_uint8_t *pa, *pa_end;
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at->emft_buf = grub_malloc (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR);
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if (at->emft_buf == NULL)
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@@ -209,11 +209,13 @@ find_attr (struct grub_ntfs_attr *at, grub_uint8_t attr)
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}
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at->attr_nxt = at->edat_buf;
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at->attr_end = at->edat_buf + u32at (pa, 0x30);
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+ pa_end = at->edat_buf + n;
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}
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else
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{
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at->attr_nxt = at->attr_end + u16at (pa, 0x14);
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at->attr_end = at->attr_end + u32at (pa, 4);
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+ pa_end = at->mft->buf + (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR);
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}
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at->flags |= GRUB_NTFS_AF_ALST;
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while (at->attr_nxt < at->attr_end)
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@@ -230,6 +232,13 @@ find_attr (struct grub_ntfs_attr *at, grub_uint8_t attr)
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at->flags |= GRUB_NTFS_AF_GPOS;
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at->attr_cur = at->attr_nxt;
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pa = at->attr_cur;
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+
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+ if ((pa >= pa_end) || (pa_end - pa < 0x18))
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+ {
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+ grub_error (GRUB_ERR_BAD_FS, "can\'t parse attribute list");
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+ return NULL;
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+ }
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+
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grub_set_unaligned32 ((char *) pa + 0x10,
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grub_cpu_to_le32 (at->mft->data->mft_start));
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grub_set_unaligned32 ((char *) pa + 0x14,
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@@ -240,6 +249,13 @@ find_attr (struct grub_ntfs_attr *at, grub_uint8_t attr)
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{
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if (*pa != attr)
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break;
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+
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+ if ((pa >= pa_end) || (pa_end - pa < 0x18))
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+ {
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+ grub_error (GRUB_ERR_BAD_FS, "can\'t parse attribute list");
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+ return NULL;
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+ }
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+
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if (read_attr
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(at, pa + 0x10,
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u32at (pa, 0x10) * (at->mft->data->mft_size << GRUB_NTFS_BLK_SHR),
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