Only move the state machine to ReceivingData if there is no pending error. This avoids later OOB access while processing commands queued.
"SD Specifications Part 1 Physical Layer Simplified Spec. v3.01" 4.3.3 Data Read Read command is rejected if BLOCK_LEN_ERROR or ADDRESS_ERROR occurred and no data transfer is performed. 4.3.4 Data Write Write command is rejected if BLOCK_LEN_ERROR or ADDRESS_ERROR occurred and no data transfer is performed. WP_VIOLATION errors are not modified: the error bit is set, we stay in receive-data state, wait for a stop command. All further data transfer is ignored. See the check on sd->card_status at the beginning of sd_read_data() and sd_write_data(). Fixes: CVE-2020-13253 Cc: Prasad J Pandit <p...@fedoraproject.org> Reported-by: Alexander Bulekov <alx...@bu.edu> Buglink: https://bugs.launchpad.net/qemu/+bug/1880822 Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org> --- v4: Only modify ADDRESS_ERROR, not WP_VIOLATION (pm215) --- hw/sd/sd.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/hw/sd/sd.c b/hw/sd/sd.c index 04451fdad2..7e0d684aca 100644 --- a/hw/sd/sd.c +++ b/hw/sd/sd.c @@ -1167,13 +1167,15 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req) case 17: /* CMD17: READ_SINGLE_BLOCK */ switch (sd->state) { case sd_transfer_state: - sd->state = sd_sendingdata_state; - sd->data_start = addr; - sd->data_offset = 0; if (sd->data_start + sd->blk_len > sd->size) { sd->card_status |= ADDRESS_ERROR; + return sd_r1; } + + sd->state = sd_sendingdata_state; + sd->data_start = addr; + sd->data_offset = 0; return sd_r1; default: @@ -1184,13 +1186,15 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req) case 18: /* CMD18: READ_MULTIPLE_BLOCK */ switch (sd->state) { case sd_transfer_state: - sd->state = sd_sendingdata_state; - sd->data_start = addr; - sd->data_offset = 0; if (sd->data_start + sd->blk_len > sd->size) { sd->card_status |= ADDRESS_ERROR; + return sd_r1; } + + sd->state = sd_sendingdata_state; + sd->data_start = addr; + sd->data_offset = 0; return sd_r1; default: @@ -1230,14 +1234,17 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req) /* Writing in SPI mode not implemented. */ if (sd->spi) break; + + if (sd->data_start + sd->blk_len > sd->size) { + sd->card_status |= ADDRESS_ERROR; + return sd_r1; + } + 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) { - sd->card_status |= ADDRESS_ERROR; - } if (sd_wp_addr(sd, sd->data_start)) { sd->card_status |= WP_VIOLATION; } @@ -1257,14 +1264,17 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, SDRequest req) /* Writing in SPI mode not implemented. */ if (sd->spi) break; + + if (sd->data_start + sd->blk_len > sd->size) { + sd->card_status |= ADDRESS_ERROR; + return sd_r1; + } + 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) { - sd->card_status |= ADDRESS_ERROR; - } if (sd_wp_addr(sd, sd->data_start)) { sd->card_status |= WP_VIOLATION; } -- 2.21.3