Avoid OOB access by verifying the requested address belong to the actual card size. Return ADDRESS_ERROR when not in range. Only move the state machine to ReceivingData if there is no pending error.
"SD Specifications Part 1 Physical Layer Simplified Spec. v3.01" 4.3.4 Data Write * Block Write Write command is rejected if BLOCK_LEN_ERROR or ADDRESS_ERROR occurred and no data transfer is performed. Fixes: CVE-2020-13253 Reported-by: Alexander Bulekov <alx...@bu.edu> Buglink: https://bugs.launchpad.net/qemu/+bug/1880822 Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org> --- Cc: Prasad J Pandit <p...@fedoraproject.org> v2: check for blksz in range, only go to sd_receivingdata_state if no error. --- hw/sd/sd.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/hw/sd/sd.c b/hw/sd/sd.c index 3c06a0ac6d..2254dc7acc 100644 --- a/hw/sd/sd.c +++ b/hw/sd/sd.c @@ -1211,17 +1211,18 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req) /* Writing in SPI mode not implemented. */ if (sd->spi) break; - sd->state = sd_receivingdata_state; - sd->data_start = addr; - sd->data_offset = 0; - sd->blk_written = 0; - - if (sd->data_start + sd->blk_len > sd->size) + if (addr + sd->blk_len >= sd->size) { sd->card_status |= ADDRESS_ERROR; - if (sd_wp_addr(sd, sd->data_start)) + } else if (sd_wp_addr(sd, sd->data_start)) { sd->card_status |= WP_VIOLATION; - if (sd->csd[14] & 0x30) + } else if (sd->csd[14] & 0x30) { sd->card_status |= WP_VIOLATION; + } else { + sd->state = sd_receivingdata_state; + sd->data_start = addr; + sd->data_offset = 0; + sd->blk_written = 0; + } return sd_r1; default: -- 2.21.3
