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From 0453588f95294ed5ce912cb8b810a322bf9d91e0 Mon Sep 17 00:00:00 2001
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From: Jon Maloy <jmaloy@redhat.com>
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Date: Thu, 25 Feb 2021 19:43:02 -0500
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Subject: [PATCH] ide: atapi: check logical block address and read size
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 (CVE-2020-29443)
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Jon Maloy <jmaloy@redhat.com>
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Message-id: <20210225194302.3137699-2-jmaloy@redhat.com>
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Patchwork-id: 101208
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O-Subject: [RHEL-8.4.0 qemu-kvm PATCH v2 1/1] ide: atapi: check logical block address and read size (CVE-2020-29443)
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Bugzilla: 1917451
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Danilo de Paula <ddepaula@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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From: Prasad J Pandit <pjp@fedoraproject.org>
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While processing ATAPI cmd_read/cmd_read_cd commands,
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Logical Block Address (LBA) maybe invalid OR closer to the last block,
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leading to an OOB access issues. Add range check to avoid it.
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Fixes: CVE-2020-29443
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Reported-by: Wenxiang Qian <leonwxqian@gmail.com>
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Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
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Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Message-Id: <20210118115130.457044-1-ppandit@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit b8d7f1bc59276fec85e4d09f1567613a3e14d31e)
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Signed-off-by: Jon Maloy <jmaloy@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/ide/atapi.c | 30 ++++++++++++++++++++++++------
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 1 file changed, 24 insertions(+), 6 deletions(-)
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diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
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index 17a9d635d8..d064935c8d 100644
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--- a/hw/ide/atapi.c
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+++ b/hw/ide/atapi.c
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@@ -320,6 +320,8 @@ static void ide_atapi_cmd_reply(IDEState *s, int size, int max_size)
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 static void ide_atapi_cmd_read_pio(IDEState *s, int lba, int nb_sectors,
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                                    int sector_size)
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 {
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+    assert(0 <= lba && lba < (s->nb_sectors >> 2));
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+
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     s->lba = lba;
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     s->packet_transfer_size = nb_sectors * sector_size;
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     s->elementary_transfer_size = 0;
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@@ -418,6 +420,8 @@ eot:
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 static void ide_atapi_cmd_read_dma(IDEState *s, int lba, int nb_sectors,
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                                    int sector_size)
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 {
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+    assert(0 <= lba && lba < (s->nb_sectors >> 2));
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+
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     s->lba = lba;
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     s->packet_transfer_size = nb_sectors * sector_size;
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     s->io_buffer_size = 0;
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@@ -971,35 +975,49 @@ static void cmd_prevent_allow_medium_removal(IDEState *s, uint8_t* buf)
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 static void cmd_read(IDEState *s, uint8_t* buf)
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 {
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-    int nb_sectors, lba;
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+    unsigned int nb_sectors, lba;
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+
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+    /* Total logical sectors of ATAPI_SECTOR_SIZE(=2048) bytes */
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+    uint64_t total_sectors = s->nb_sectors >> 2;
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     if (buf[0] == GPCMD_READ_10) {
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         nb_sectors = lduw_be_p(buf + 7);
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     } else {
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         nb_sectors = ldl_be_p(buf + 6);
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     }
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-
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-    lba = ldl_be_p(buf + 2);
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     if (nb_sectors == 0) {
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         ide_atapi_cmd_ok(s);
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         return;
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     }
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+    lba = ldl_be_p(buf + 2);
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+    if (lba >= total_sectors || lba + nb_sectors - 1 >= total_sectors) {
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+        ide_atapi_cmd_error(s, ILLEGAL_REQUEST, ASC_LOGICAL_BLOCK_OOR);
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+        return;
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+    }
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+
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     ide_atapi_cmd_read(s, lba, nb_sectors, 2048);
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 }
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 static void cmd_read_cd(IDEState *s, uint8_t* buf)
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 {
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-    int nb_sectors, lba, transfer_request;
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+    unsigned int nb_sectors, lba, transfer_request;
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-    nb_sectors = (buf[6] << 16) | (buf[7] << 8) | buf[8];
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-    lba = ldl_be_p(buf + 2);
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+    /* Total logical sectors of ATAPI_SECTOR_SIZE(=2048) bytes */
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+    uint64_t total_sectors = s->nb_sectors >> 2;
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+    nb_sectors = (buf[6] << 16) | (buf[7] << 8) | buf[8];
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     if (nb_sectors == 0) {
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         ide_atapi_cmd_ok(s);
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         return;
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     }
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+    lba = ldl_be_p(buf + 2);
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+    if (lba >= total_sectors || lba + nb_sectors - 1 >= total_sectors) {
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+        ide_atapi_cmd_error(s, ILLEGAL_REQUEST, ASC_LOGICAL_BLOCK_OOR);
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+        return;
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+    }
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+
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     transfer_request = buf[9] & 0xf8;
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     if (transfer_request == 0x00) {
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         /* nothing */
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-- 
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2.27.0
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