In the Linux kernel, the following vulnerability has been resolved: RDMA/srp: fix heap information leak on a truncated SRP_CRED_REQ srp_re

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

RDMA/srp: fix heap information leak on a truncated SRP_CRED_REQ

srp_recv_done() passes wc->byte_len to srp_process_rsp(). It passes
nothing to srp_process_cred_req() and srp_process_aer_req(), which read
fixed-size fields from the receive buffer without checking that those
fields were received.

The buffer size is max_ti_iu_len, which comes from the login response
and is not validated. A target that advertises 8 and then sends an
8-byte SRP_CRED_REQ makes the initiator read req->tag from beyond the
end of the buffer. req->tag is copied into the SRP_CRED_RSP and sent
back, so those bytes reach the target. SRP_AER_REQ behaves the same way
and also reads req->lun.

The leak is 8 bytes per response. max_ti_iu_len also decides which slab
cache the buffer comes from. With 8 the buffer is a kmalloc-8 object and
the read is entirely outside it:

BUG: KASAN: slab-out-of-bounds in srp_recv_done+0x172b/0x1aa0
Read of size 8 at addr ffff888104714da8 by task kworker/u8:3/50
which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of
allocated 8-byte region [ffff888104714da0, ffff888104714da8)

Without KASAN the returned bytes are whatever is next in the slab. One
run returned ".strtab".

rsp->data[3] in srp_process_rsp() has the same problem: only
resp_data_len is checked before it is read.

Drop a request that is shorter than the structure being parsed, and
check byte_len before the tsk_mgmt read.