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    Subject[PATCH 4.19 24/58] scsi: megaraid_sas: Fix MEGASAS_IOC_FIRMWARE regression
    Date
    From: Arnd Bergmann <arnd@arndb.de>

    [ Upstream commit b112036535eda34460677ea883eaecc3a45a435d ]

    Phil Oester reported that a fix for a possible buffer overrun that I sent
    caused a regression that manifests in this output:

    Event Message: A PCI parity error was detected on a component at bus 0 device 5 function 0.
    Severity: Critical
    Message ID: PCI1308

    The original code tried to handle the sense data pointer differently when
    using 32-bit 64-bit DMA addressing, which would lead to a 32-bit dma_addr_t
    value of 0x11223344 to get stored

    32-bit kernel: 44 33 22 11 ?? ?? ?? ??
    64-bit LE kernel: 44 33 22 11 00 00 00 00
    64-bit BE kernel: 00 00 00 00 44 33 22 11

    or a 64-bit dma_addr_t value of 0x1122334455667788 to get stored as

    32-bit kernel: 88 77 66 55 ?? ?? ?? ??
    64-bit kernel: 88 77 66 55 44 33 22 11

    In my patch, I tried to ensure that the same value is used on both 32-bit
    and 64-bit kernels, and picked what seemed to be the most sensible
    combination, storing 32-bit addresses in the first four bytes (as 32-bit
    kernels already did), and 64-bit addresses in eight consecutive bytes (as
    64-bit kernels already did), but evidently this was incorrect.

    Always storing the dma_addr_t pointer as 64-bit little-endian,
    i.e. initializing the second four bytes to zero in case of 32-bit
    addressing, apparently solved the problem for Phil, and is consistent with
    what all 64-bit little-endian machines did before.

    I also checked in the history that in previous versions of the code, the
    pointer was always in the first four bytes without padding, and that
    previous attempts to fix 64-bit user space, big-endian architectures and
    64-bit DMA were clearly flawed and seem to have introduced made this worse.

    Link: https://lore.kernel.org/r/20210104234137.438275-1-arnd@kernel.org
    Fixes: 381d34e376e3 ("scsi: megaraid_sas: Check user-provided offsets")
    Fixes: 107a60dd71b5 ("scsi: megaraid_sas: Add support for 64bit consistent DMA")
    Fixes: 94cd65ddf4d7 ("[SCSI] megaraid_sas: addded support for big endian architecture")
    Fixes: 7b2519afa1ab ("[SCSI] megaraid_sas: fix 64 bit sense pointer truncation")
    Reported-by: Phil Oester <kernel@linuxace.com>
    Tested-by: Phil Oester <kernel@linuxace.com>
    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/scsi/megaraid/megaraid_sas_base.c | 6 ++----
    1 file changed, 2 insertions(+), 4 deletions(-)

    diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
    index 83d25ee88f028..8877a21102f1d 100644
    --- a/drivers/scsi/megaraid/megaraid_sas_base.c
    +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
    @@ -7323,11 +7323,9 @@ megasas_mgmt_fw_ioctl(struct megasas_instance *instance,
    goto out;
    }

    + /* always store 64 bits regardless of addressing */
    sense_ptr = (void *)cmd->frame + ioc->sense_off;
    - if (instance->consistent_mask_64bit)
    - put_unaligned_le64(sense_handle, sense_ptr);
    - else
    - put_unaligned_le32(sense_handle, sense_ptr);
    + put_unaligned_le64(sense_handle, sense_ptr);
    }

    /*
    --
    2.27.0


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