From: Rustam Kovhaev <rkovh...@gmail.com>

commit 4dfe6bd94959222e18d512bdf15f6bf9edb9c27c upstream.

Mounting a corrupted filesystem with NTFS resulted in a kernel crash.

We should check for valid STANDARD_INFORMATION attribute offset and length
before trying to access it

Link: https://lkml.kernel.org/r/20210217155930.1506815-1-rkovh...@gmail.com
Link: https://syzkaller.appspot.com/bug?extid=c584225dabdea2f71969
Signed-off-by: Rustam Kovhaev <rkovh...@gmail.com>
Reported-by: syzbot+c584225dabdea2f71...@syzkaller.appspotmail.com
Tested-by: syzbot+c584225dabdea2f71...@syzkaller.appspotmail.com
Acked-by: Anton Altaparmakov <an...@tuxera.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 fs/ntfs/inode.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -629,6 +629,12 @@ static int ntfs_read_locked_inode(struct
        }
        a = ctx->attr;
        /* Get the standard information attribute value. */
+       if ((u8 *)a + le16_to_cpu(a->data.resident.value_offset)
+                       + le32_to_cpu(a->data.resident.value_length) >
+                       (u8 *)ctx->mrec + vol->mft_record_size) {
+               ntfs_error(vi->i_sb, "Corrupt standard information attribute in 
inode.");
+               goto unm_err_out;
+       }
        si = (STANDARD_INFORMATION*)((u8*)a +
                        le16_to_cpu(a->data.resident.value_offset));
 


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