In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
IB\/isert: reject login PDUs declaring more data than was received<\/p>\n
isert_login_recv_done() records how many bytes the HCA actually placed in
\nthe login buffer, but nothing compares that against the length the login
\nPDU’s BHS declares. isert_rx_login_req() copies min(login_req_len,
\nMAX_KEY_VALUE_PAIRS) bytes into login->req_buf, and the login code then
\nreads the declared length back out of that buffer – for the first PDU in
\niscsi_target_locate_portal(),<\/p>\n
\tpayload_length = ntoh24(login_req->dlength);
\n\ttmpbuf = kmemdup_nul(login->req_buf, payload_length, GFP_KERNEL);<\/p>\n
and for the ones after it in iscsi_decode_text_input(), reached from
\niscsi_target_do_login().<\/p>\n
login->req_buf is a fixed MAX_KEY_VALUE_PAIRS (8192) byte allocation, so
\nan initiator that declares more than it sends reads off the end of it,
\nbefore authentication and with the length under its control:<\/p>\n
BUG: KASAN: slab-out-of-bounds in kmemdup_nul+0x43\/0x80
\n Read of size 8193 at addr ffff8881056a8000 by task iscsi_np\/167
\n __asan_memcpy+0x23\/0x60
\n kmemdup_nul+0x43\/0x80
\n iscsi_target_locate_portal+0x48d\/0x1180
\n iscsi_target_login_thread+0x19a9\/0x3350
\n Allocated by task 167:
\n __kmalloc_cache_noprof+0x158\/0x370
\n iscsi_target_login_thread+0x971\/0x3350
\n which belongs to the cache kmalloc-8k of size 8192
\n allocated 8192-byte region<\/p>\n
Falsifying the second login PDU instead reaches the other reader, on the
\nsame buffer:<\/p>\n
BUG: KASAN: slab-out-of-bounds in kmemdup_nul+0x43\/0x80
\n Read of size 8193 at addr ffff888104d10000 by task kworker\/1:1\/50
\n Workqueue: isert_login_wq iscsi_target_do_login_rx
\n __asan_memcpy+0x23\/0x60
\n kmemdup_nul+0x43\/0x80
\n iscsi_decode_text_input+0xc6\/0x11c0
\n iscsi_target_do_login+0x261\/0x1470
\n iscsi_target_do_login_rx+0x51d\/0x7d0<\/p>\n
iscsit over TCP is not exposed: iscsit_get_login_rx() validates the
\ndeclared length with iscsi_target_check_login_request() and then reads
\nexactly that many bytes off the socket, so the declared length governs
\nhow much arrives rather than how much is copied out of an already-filled
\nbuffer. isert does not call iscsi_target_check_login_request() at all.<\/p>\n
Reject a login PDU whose declared DataSegmentLength exceeds what was
\nreceived, in both paths that reach isert_rx_login_req():
\nisert_get_login_rx() for the first login PDU and isert_login_recv_done()
\nfor the ones after it. dlength <= login_req_len is allowed because the
\nreceived count can include up to three bytes of iSCSI padding.<\/p>\n
Once the check is in place the copy out can no longer exceed the copy in:
\nthe posted login SGE is ISER_RX_PAYLOAD_SIZE, so login_req_len cannot
\nexceed MAX_KEY_VALUE_PAIRS and the min() in isert_rx_login_req() is
\nlogin_req_len.<\/p>\n
Like the existing short-PDU check added by 29e7b925ae6d, the reject in
\nisert_login_recv_done() returns without completing login_req_comp, so a
\nmalformed subsequent PDU leaves the login to be torn down by the login
\ntimer rather than failing immediately. The first-PDU path returns an
\nerror and fails straight away.<\/p>\n
Reproduced on 7.2.0-rc4 with soft-RoCE (rdma_rxe) under KASAN, using an
\ninitiator that sends the real key=value payload while declaring 8193 in
\nthe BHS, on the first login PDU and on the second in separate runs. The
\nreported read size tracks the declared value exactly; 16384 and 61440
\nbehave the same. Unpatched 3 of 3 runs report on each of the two paths,
\npatched 0 of 3 on both, run alternately in a single session, and a normal
\nlogin still completes on the patched build.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
IB\/isert: reject login PDUs declaring more data than was received<\/p>\n
isert_login_recv_done() records how many bytes the HCA actually <\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-25822","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/25822","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25822"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25822"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25822"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}