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    Subject[PATCH AUTOSEL 5.4 18/37] scsi: target: pscsi: Fix possible null-pointer dereference in pscsi_complete_cmd()
    Date
    From: Tuo Li <islituo@gmail.com>

    [ Upstream commit 0f99792c01d1d6d35b86e850e9ccadd98d6f3e0c ]

    The return value of transport_kmap_data_sg() is assigned to the variable
    buf:

    buf = transport_kmap_data_sg(cmd);

    And then it is checked:

    if (!buf) {

    This indicates that buf can be NULL. However, it is dereferenced in the
    following statements:

    if (!(buf[3] & 0x80))
    buf[3] |= 0x80;
    if (!(buf[2] & 0x80))
    buf[2] |= 0x80;

    To fix these possible null-pointer dereferences, dereference buf and call
    transport_kunmap_data_sg() only when buf is not NULL.

    Link: https://lore.kernel.org/r/20210810040414.248167-1-islituo@gmail.com
    Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
    Reviewed-by: Bodo Stroesser <bostroesser@gmail.com>
    Signed-off-by: Tuo Li <islituo@gmail.com>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/target/target_core_pscsi.c | 18 +++++++++---------
    1 file changed, 9 insertions(+), 9 deletions(-)

    diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
    index 55fe93296deb..17811bb07e9f 100644
    --- a/drivers/target/target_core_pscsi.c
    +++ b/drivers/target/target_core_pscsi.c
    @@ -622,17 +622,17 @@ static void pscsi_complete_cmd(struct se_cmd *cmd, u8 scsi_status,
    buf = transport_kmap_data_sg(cmd);
    if (!buf) {
    ; /* XXX: TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE */
    - }
    -
    - if (cdb[0] == MODE_SENSE_10) {
    - if (!(buf[3] & 0x80))
    - buf[3] |= 0x80;
    } else {
    - if (!(buf[2] & 0x80))
    - buf[2] |= 0x80;
    - }
    + if (cdb[0] == MODE_SENSE_10) {
    + if (!(buf[3] & 0x80))
    + buf[3] |= 0x80;
    + } else {
    + if (!(buf[2] & 0x80))
    + buf[2] |= 0x80;
    + }

    - transport_kunmap_data_sg(cmd);
    + transport_kunmap_data_sg(cmd);
    + }
    }
    }
    after_mode_sense:
    --
    2.30.2
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