reveliofuzzing reported that a SCSI_IOCTL_SEND_COMMAND ioctl with out_len set to 0xd42, SCSI command set to ATA_16 PASS-THROUGH, ATA command set to ATA_NOP, and protocol set to ATA_PROT_PIO, can cause ata_pio_sector() to write outside the allocated buffer, overwriting random memory. While a ATA device is supposed to abort a ATA_NOP command, there does seem to be a bug either in libata-sff or QEMU, where either this status is not set, or the status is cleared before read by ata_sff_hsm_move(). Anyway, that is most likely a separate bug. Looking at __atapi_pio_bytes(), it already has a safety check to ensure that __atapi_pio_bytes() cannot write outside the allocated buffer. Add a similar check to ata_pio_sector(), such that also ata_pio_sector() cannot write outside the allocated buffer. Reported-by: reveliofuzzing <reveliofuzzing@xxxxxxxxx> Closes: https://lore.kernel.org/linux-ide/CA+-ZZ_jTgxh3bS7m+KX07_EWckSnW3N2adX3KV63y4g7M4CZ2A@xxxxxxxxxxxxxx/ Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx> --- drivers/ata/libata-sff.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c index 67f277e1c3bf..5a46c066abc3 100644 --- a/drivers/ata/libata-sff.c +++ b/drivers/ata/libata-sff.c @@ -601,7 +601,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc) { struct ata_port *ap = qc->ap; struct page *page; - unsigned int offset; + unsigned int offset, count; if (!qc->cursg) { qc->curbytes = qc->nbytes; @@ -617,25 +617,27 @@ static void ata_pio_sector(struct ata_queued_cmd *qc) page = nth_page(page, (offset >> PAGE_SHIFT)); offset %= PAGE_SIZE; - trace_ata_sff_pio_transfer_data(qc, offset, qc->sect_size); + /* don't overrun current sg */ + count = min(qc->cursg->length - qc->cursg_ofs, qc->sect_size); + + trace_ata_sff_pio_transfer_data(qc, offset, count); /* * Split the transfer when it splits a page boundary. Note that the * split still has to be dword aligned like all ATA data transfers. */ WARN_ON_ONCE(offset % 4); - if (offset + qc->sect_size > PAGE_SIZE) { + if (offset + count > PAGE_SIZE) { unsigned int split_len = PAGE_SIZE - offset; ata_pio_xfer(qc, page, offset, split_len); - ata_pio_xfer(qc, nth_page(page, 1), 0, - qc->sect_size - split_len); + ata_pio_xfer(qc, nth_page(page, 1), 0, count - split_len); } else { - ata_pio_xfer(qc, page, offset, qc->sect_size); + ata_pio_xfer(qc, page, offset, count); } - qc->curbytes += qc->sect_size; - qc->cursg_ofs += qc->sect_size; + qc->curbytes += count; + qc->cursg_ofs += count; if (qc->cursg_ofs == qc->cursg->length) { qc->cursg = sg_next(qc->cursg); -- 2.48.1
