CVE-2021-47130: nvmet: fix freeing unallocated p2pmem

CVE-2021-47130: nvmet: fix freeing unallocated p2pmem

[Greg Kroah-Hartman]

Description
===========

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

nvmet: fix freeing unallocated p2pmem

In case p2p device was found but the p2p pool is empty, the nvme target
is still trying to free the sgl from the p2p pool instead of the
regular sgl pool and causing a crash (BUG() is called). Instead, assign
the p2p_dev for the request only if it was allocated from p2p pool.

This is the crash that was caused:

[Sun May 30 19:13:53 2021] ------------[ cut here ]------------
[Sun May 30 19:13:53 2021] kernel BUG at lib/genalloc.c:518!
[Sun May 30 19:13:53 2021] invalid opcode: 0000 [#1] SMP PTI
...
[Sun May 30 19:13:53 2021] kernel BUG at lib/genalloc.c:518!
...
[Sun May 30 19:13:53 2021] RIP: 0010:gen_pool_free_owner+0xa8/0xb0
...
[Sun May 30 19:13:53 2021] Call Trace:
[Sun May 30 19:13:53 2021] ------------[ cut here ]------------
[Sun May 30 19:13:53 2021]  pci_free_p2pmem+0x2b/0x70
[Sun May 30 19:13:53 2021]  pci_p2pmem_free_sgl+0x4f/0x80
[Sun May 30 19:13:53 2021]  nvmet_req_free_sgls+0x1e/0x80 [nvmet]
[Sun May 30 19:13:53 2021] kernel BUG at lib/genalloc.c:518!
[Sun May 30 19:13:53 2021]  nvmet_rdma_release_rsp+0x4e/0x1f0 [nvmet_rdma]
[Sun May 30 19:13:53 2021]  nvmet_rdma_send_done+0x1c/0x60 [nvmet_rdma]

The Linux kernel CVE team has assigned CVE-2021-47130 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.8 with commit c6e3f1339812 and fixed in 5.10.43 with commit c440cd080761
	Issue introduced in 5.8 with commit c6e3f1339812 and fixed in 5.12.10 with commit 8a452d62e7ce
	Issue introduced in 5.8 with commit c6e3f1339812 and fixed in 5.13 with commit bcd9a0797d73

Please see https://www.kernel.org or a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47130
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/nvme/target/core.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/c440cd080761b18a52cac20f2a42e5da1e3995af
	https://git.kernel.org/stable/c/8a452d62e7cea3c8a2676a3b89a9118755a1a271
	https://git.kernel.org/stable/c/bcd9a0797d73eeff659582f23277e7ab6e5f18f3