| Message ID | 20160915032044.GB9309@birch.djwong.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/fs/ioctl.c b/fs/ioctl.c index 26aba09..c415668 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -582,6 +582,10 @@ static int ioctl_file_dedupe_range(struct file *file, void __user *arg) } size = offsetof(struct file_dedupe_range __user, info[count]); + if (size > PAGE_SIZE) { + ret = -ENOMEM; + goto out; + } same = memdup_user(argp, size); if (IS_ERR(same)) {
Kirill A. Shutemov reports that the kernel doesn't try to cap dest_count in any way, and uses the number to allocate kernel memory. This causes high order allocation warnings in the kernel log if someone passes in a big enough value. We should clamp the allocation at PAGE_SIZE to avoid stressing the VM. The two existing users of the dedupe ioctl never send more than 120 requests, so we can safely clamp dest_range at PAGE_SIZE, because with 4k pages we can handle up to 127 dedupe candidates. Given the max extent length of 16MB, we can end up doing 2GB of IO which is plenty. Reported-by: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> --- fs/ioctl.c | 4 ++++ 1 file changed, 4 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html