+ ntfs-add-check-for-mft-record-size-in-superblock.patch added to -mm tree

+ ntfs-add-check-for-mft-record-size-in-superblock.patch added to -mm tree

[akpm]

The patch titled
     Subject: ntfs: add check for mft record size in superblock
has been added to the -mm tree.  Its filename is
     ntfs-add-check-for-mft-record-size-in-superblock.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/ntfs-add-check-for-mft-record-size-in-superblock.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/ntfs-add-check-for-mft-record-size-in-superblock.patch

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------------------------------------------------------
From: Rustam Kovhaev <rkovhaev@gmail.com>
Subject: ntfs: add check for mft record size in superblock

Number of bytes allocated for mft record should be equal to the mft record
size stored in ntfs superblock as reported by syzbot, userspace might
trigger out-of-bounds read by dereferencing ctx->attr in ntfs_attr_find()

Link: https://syzkaller.appspot.com/bug?extid=aed06913f36eff9b544e
Link: https://lkml.kernel.org/r/20200824022804.226242-1-rkovhaev@gmail.com
Reported-by: syzbot+aed06913f36eff9b544e@syzkaller.appspotmail.com
Tested-by: syzbot+aed06913f36eff9b544e@syzkaller.appspotmail.com
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Acked-by: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ntfs/inode.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/ntfs/inode.c~ntfs-add-check-for-mft-record-size-in-superblock
+++ a/fs/ntfs/inode.c
@@ -1810,6 +1810,12 @@ int ntfs_read_inode_mount(struct inode *
 		brelse(bh);
 	}
 
+	if (le32_to_cpu(m->bytes_allocated) != vol->mft_record_size) {
+		ntfs_error(sb, "Incorrect mft record size %u in superblock, should be %u.",
+				le32_to_cpu(m->bytes_allocated), vol->mft_record_size);
+		goto err_out;
+	}
+
 	/* Apply the mst fixups. */
 	if (post_read_mst_fixup((NTFS_RECORD*)m, vol->mft_record_size)) {
 		/* FIXME: Try to use the $MFTMirr now. */
_

Patches currently in -mm which might be from rkovhaev@gmail.com are

scripts-tagssh-exclude-tools-directory-from-tags-generation.patch
ntfs-add-check-for-mft-record-size-in-superblock.patch