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[PATCH v3] ide: atapi: check logical block address and read size (CVE-20
From: |
P J P |
Subject: |
[PATCH v3] ide: atapi: check logical block address and read size (CVE-2020-29443) |
Date: |
Mon, 18 Jan 2021 17:21:30 +0530 |
From: Prasad J Pandit <pjp@fedoraproject.org>
While processing ATAPI cmd_read/cmd_read_cd commands,
Logical Block Address (LBA) maybe invalid OR closer to the last block,
leading to an OOB access issues. Add range check to avoid it.
Fixes: CVE-2020-29443
Reported-by: Wenxiang Qian <leonwxqian@gmail.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
hw/ide/atapi.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)
Update v3: Fix space typo/error, add Reviewed-by tag
-> https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg04159.html
-> https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg04173.html
diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index e79157863f..b626199e3d 100644
--- a/hw/ide/atapi.c
+++ b/hw/ide/atapi.c
@@ -322,6 +322,8 @@ static void ide_atapi_cmd_reply(IDEState *s, int size, int
max_size)
static void ide_atapi_cmd_read_pio(IDEState *s, int lba, int nb_sectors,
int sector_size)
{
+ assert(0 <= lba && lba < (s->nb_sectors >> 2));
+
s->lba = lba;
s->packet_transfer_size = nb_sectors * sector_size;
s->elementary_transfer_size = 0;
@@ -420,6 +422,8 @@ eot:
static void ide_atapi_cmd_read_dma(IDEState *s, int lba, int nb_sectors,
int sector_size)
{
+ assert(0 <= lba && lba < (s->nb_sectors >> 2));
+
s->lba = lba;
s->packet_transfer_size = nb_sectors * sector_size;
s->io_buffer_size = 0;
@@ -973,35 +977,49 @@ static void cmd_prevent_allow_medium_removal(IDEState *s,
uint8_t* buf)
static void cmd_read(IDEState *s, uint8_t* buf)
{
- int nb_sectors, lba;
+ unsigned int nb_sectors, lba;
+
+ /* Total logical sectors of ATAPI_SECTOR_SIZE(=2048) bytes */
+ uint64_t total_sectors = s->nb_sectors >> 2;
if (buf[0] == GPCMD_READ_10) {
nb_sectors = lduw_be_p(buf + 7);
} else {
nb_sectors = ldl_be_p(buf + 6);
}
-
- lba = ldl_be_p(buf + 2);
if (nb_sectors == 0) {
ide_atapi_cmd_ok(s);
return;
}
+ lba = ldl_be_p(buf + 2);
+ if (lba >= total_sectors || lba + nb_sectors - 1 >= total_sectors) {
+ ide_atapi_cmd_error(s, ILLEGAL_REQUEST, ASC_LOGICAL_BLOCK_OOR);
+ return;
+ }
+
ide_atapi_cmd_read(s, lba, nb_sectors, 2048);
}
static void cmd_read_cd(IDEState *s, uint8_t* buf)
{
- int nb_sectors, lba, transfer_request;
+ unsigned int nb_sectors, lba, transfer_request;
+
+ /* Total logical sectors of ATAPI_SECTOR_SIZE(=2048) bytes */
+ uint64_t total_sectors = s->nb_sectors >> 2;
nb_sectors = (buf[6] << 16) | (buf[7] << 8) | buf[8];
- lba = ldl_be_p(buf + 2);
-
if (nb_sectors == 0) {
ide_atapi_cmd_ok(s);
return;
}
+ lba = ldl_be_p(buf + 2);
+ if (lba >= total_sectors || lba + nb_sectors - 1 >= total_sectors) {
+ ide_atapi_cmd_error(s, ILLEGAL_REQUEST, ASC_LOGICAL_BLOCK_OOR);
+ return;
+ }
+
transfer_request = buf[9] & 0xf8;
if (transfer_request == 0x00) {
/* nothing */
--
2.29.2
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