CVE-2023-52636

In the Linux kernel, the following vulnerability has been resolved:

libceph: just wait for more data to be available on the socket

A short read may occur while reading the message footer from the

socket. Later, when the socket is ready for another read, the

messenger invokes all read_partial_*() handlers, including

read_partial_sparse_msg_data(). The expectation is that

read_partial_sparse_msg_data() would bail, allowing the messenger to

invoke read_partial() for the footer and pick up where it left off.

However read_partial_sparse_msg_data() violates that and ends up

calling into the state machine in the OSD client. The sparse-read

state machine assumes that it's a new op and interprets some piece of

the footer as the sparse-read header and returns bogus extents/data

length, etc.

To determine whether read_partial_sparse_msg_data() should bail, let's

reuse cursor->total_resid. Because once it reaches to zero that means

all the extents and data have been successfully received in last read,

else it could break out when partially reading any of the extents and

data. And then osd_sparse_read() could continue where it left off.

[ idryomov: changelog ]