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bhyve nvme: Check return value of mapped memory

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Fuzzing of bhyve using hyfuzz discovered a way to cause a segmentation
fault in the NVMe emulation. If a guest specifies a physical address in
either the PRP1 or PRP2 field of a command that cannot be mapped from
guest to host, the function paddr_guest2host() returns a NULL pointer.
The NVMe emulation did not check for this error case, which allowed for
the segmentation fault to occur.

Fix is to check for a return value of NULL and indicate an error back to
the guest (Data Transfer error). While in the area, slightly refactor
the write/read blockif function to use a common error exit path.

PR:		256321
Reported by:	Cheolwoo Myung <cwmyung@snu.ac.kr>
Reviewed by:	imp, jhb
Differential Revision:	https://reviews.freebsd.org/D35452
This commit is contained in:
Chuck Tuffli 2022-08-14 07:45:21 -07:00
parent 8b55a4718c
commit 3d3678627c
1 changed files with 13 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
usr.sbin/bhyve/pci_nvme.c
View File

@ -2196,6 +2196,8 @@ pci_nvme_append_iov_req(struct pci_nvme_softc *sc, struct pci_nvme_ioreq *req,
req->io_req.br_iov[iovidx].iov_base =
paddr_guest2host(req->sc->nsc_pi->pi_vmctx,
req->prev_gpaddr, size);
if (req->io_req.br_iov[iovidx].iov_base == NULL)
return (-1);
req->prev_size += size;
req->io_req.br_resid += size;
@ -2212,6 +2214,8 @@ pci_nvme_append_iov_req(struct pci_nvme_softc *sc, struct pci_nvme_ioreq *req,
req->io_req.br_iov[iovidx].iov_base =
paddr_guest2host(req->sc->nsc_pi->pi_vmctx,
gpaddr, size);
if (req->io_req.br_iov[iovidx].iov_base == NULL)
return (-1);
req->io_req.br_iov[iovidx].iov_len = size;
@ -2402,8 +2406,7 @@ nvme_write_read_blockif(struct pci_nvme_softc *sc,
size = MIN(PAGE_SIZE - (prp1 % PAGE_SIZE), bytes);
if (pci_nvme_append_iov_req(sc, req, prp1,
size, is_write, offset)) {
pci_nvme_status_genc(&status,
NVME_SC_DATA_TRANSFER_ERROR);
err = -1;
goto out;
}
@ -2416,8 +2419,7 @@ nvme_write_read_blockif(struct pci_nvme_softc *sc,
size = bytes;
if (pci_nvme_append_iov_req(sc, req, prp2,
size, is_write, offset)) {
pci_nvme_status_genc(&status,
NVME_SC_DATA_TRANSFER_ERROR);
err = -1;
goto out;
}
} else {
@ -2433,6 +2435,10 @@ nvme_write_read_blockif(struct pci_nvme_softc *sc,
prp_list = paddr_guest2host(vmctx, prp,
PAGE_SIZE - (prp % PAGE_SIZE));
if (prp_list == NULL) {
err = -1;
goto out;
}
last = prp_list + (NVME_PRP2_ITEMS - 1);
}
@ -2440,8 +2446,7 @@ nvme_write_read_blockif(struct pci_nvme_softc *sc,
if (pci_nvme_append_iov_req(sc, req, *prp_list,
size, is_write, offset)) {
pci_nvme_status_genc(&status,
NVME_SC_DATA_TRANSFER_ERROR);
err = -1;
goto out;
}
@ -2456,10 +2461,10 @@ nvme_write_read_blockif(struct pci_nvme_softc *sc,
err = blockif_write(nvstore->ctx, &req->io_req);
else
err = blockif_read(nvstore->ctx, &req->io_req);
out:
if (err)
pci_nvme_status_genc(&status, NVME_SC_DATA_TRANSFER_ERROR);
out:
return (status);
}