Commit ee8c13b8 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

pr-helper: avoid error on PR IN command with zero request size 



After reading a PR IN command with zero request size in prh_read_request,
the resp->result field will be uninitialized and the resp.sz field will
be also uninitialized when returning to prh_co_entry.

If resp->result == GOOD (from a previous successful reply or just luck),
then the assert in prh_write_response might not be triggered and
uninitialized response will be sent.

The fix is to remove the whole handling of sz == 0 in prh_co_entry.
Those errors apply only to PR OUT commands and it's perfectly okay to
catch them later in do_pr_out and multipath_pr_out; the check for
too-short parameters in fact doesn't apply in the easy SG_IO case, as
it can be left to the target firmware even.

The result is that prh_read_request does not fail requests anymore and
prh_co_entry becomes simpler.

Reported-by: default avatarDima Stepanov <dimastep@yandex-team.ru>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2a018f6e

scsi/qemu-pr-helper.c

+30 −33
Original line number Diff line number Diff line
@@ -455,6 +455,14 @@ static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense, 
    char transportids[PR_HELPER_DATA_SIZE];

    int r;



    if (sz < PR_OUT_FIXED_PARAM_SIZE) {

        /* Illegal request, Parameter list length error.  This isn't fatal;

         * we have read the data, send an error without closing the socket.

         */

        scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM_LEN));

        return CHECK_CONDITION;

    }



    switch (rq_servact) {

    case MPATH_PROUT_REG_SA:

    case MPATH_PROUT_RES_SA:
@@ -574,6 +582,12 @@ static int do_pr_out(int fd, const uint8_t *cdb, uint8_t *sense, 
                     const uint8_t *param, int sz)

{

    int resp_sz;



    if ((fcntl(fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {

        scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));

        return CHECK_CONDITION;

    }



#ifdef CONFIG_MPATH

    if (is_mpath(fd)) {

        return multipath_pr_out(fd, cdb, sense, param, sz);
@@ -690,21 +704,6 @@ static int coroutine_fn prh_read_request(PRHelperClient *client, 
                                 errp) < 0) {

            goto out_close;

        }

        if ((fcntl(client->fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {

            scsi_build_sense(resp->sense, SENSE_CODE(INVALID_OPCODE));

            sz = 0;

        } else if (sz < PR_OUT_FIXED_PARAM_SIZE) {

            /* Illegal request, Parameter list length error.  This isn't fatal;

             * we have read the data, send an error without closing the socket.

             */

            scsi_build_sense(resp->sense, SENSE_CODE(INVALID_PARAM_LEN));

            sz = 0;

        }

        if (sz == 0) {

            resp->result = CHECK_CONDITION;

            close(client->fd);

            client->fd = -1;

        }

    }



    req->fd = client->fd;
@@ -785,7 +784,6 @@ static void coroutine_fn prh_co_entry(void *opaque) 
            break;

        }



        if (sz > 0) {

        num_active_sockets++;

        if (req.cdb[0] == PERSISTENT_RESERVE_OUT) {

            r = do_pr_out(req.fd, req.cdb, resp.sense,
@@ -803,7 +801,6 @@ static void coroutine_fn prh_co_entry(void *opaque) 
            break;

        }

        resp.result = r;

        }



        if (prh_write_response(client, &req, &resp, &local_err) < 0) {

            break;