From 0453588f95294ed5ce912cb8b810a322bf9d91e0 Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Thu, 25 Feb 2021 19:43:02 -0500 Subject: [PATCH] ide: atapi: check logical block address and read size (CVE-2020-29443) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Jon Maloy Message-id: <20210225194302.3137699-2-jmaloy@redhat.com> Patchwork-id: 101208 O-Subject: [RHEL-8.4.0 qemu-kvm PATCH v2 1/1] ide: atapi: check logical block address and read size (CVE-2020-29443) Bugzilla: 1917451 RH-Acked-by: Philippe Mathieu-Daudé RH-Acked-by: Danilo de Paula RH-Acked-by: Paolo Bonzini From: Prasad J Pandit 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 Suggested-by: Paolo Bonzini Reviewed-by: Paolo Bonzini Signed-off-by: Prasad J Pandit Message-Id: <20210118115130.457044-1-ppandit@redhat.com> Signed-off-by: Paolo Bonzini (cherry picked from commit b8d7f1bc59276fec85e4d09f1567613a3e14d31e) Signed-off-by: Jon Maloy Signed-off-by: Danilo C. L. de Paula --- hw/ide/atapi.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c index 17a9d635d8..d064935c8d 100644 --- a/hw/ide/atapi.c +++ b/hw/ide/atapi.c @@ -320,6 +320,8 @@ 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; @@ -418,6 +420,8 @@ 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; @@ -971,35 +975,49 @@ 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; - nb_sectors = (buf[6] << 16) | (buf[7] << 8) | buf[8]; - lba = ldl_be_p(buf + 2); + /* 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]; 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 */ -- 2.27.0