From: Rustam Kovhaev rkovhaev@gmail.com
[ Upstream commit 4f8c94022f0bc3babd0a124c0a7dcdd7547bd94e ]
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()
Reported-by: syzbot+aed06913f36eff9b544e@syzkaller.appspotmail.com Signed-off-by: Rustam Kovhaev rkovhaev@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Tested-by: syzbot+aed06913f36eff9b544e@syzkaller.appspotmail.com Acked-by: Anton Altaparmakov anton@tuxera.com Link: https://syzkaller.appspot.com/bug?extid=aed06913f36eff9b544e Link: https://lkml.kernel.org/r/20200824022804.226242-1-rkovhaev@gmail.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ntfs/inode.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c index 7c410f8794124..2aa073b82d30f 100644 --- a/fs/ntfs/inode.c +++ b/fs/ntfs/inode.c @@ -1844,6 +1844,12 @@ int ntfs_read_inode_mount(struct inode *vi) 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. */