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From 714a0140fd0061b44d63bd538a2d6a7de6f59be6 Mon Sep 17 00:00:00 2001
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From: Jeff Cody <jcody@redhat.com>
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Date: Tue, 25 Mar 2014 14:23:22 +0100
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Subject: [PATCH 15/49] vpc/vhd: add bounds check for max_table_entries and block_size (CVE-2014-0144)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-16-git-send-email-kwolf@redhat.com>
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Patchwork-id: n/a
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O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 15/48] vpc/vhd: add bounds check for max_table_entries and block_size (CVE-2014-0144)
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Bugzilla: 1079455
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RH-Acked-by: Jeff Cody <jcody@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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From: Jeff Cody <jcody@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079455
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Upstream status: Embargoed
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This adds checks to make sure that max_table_entries and block_size
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are in sane ranges. Memory is allocated based on max_table_entries,
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and block_size is used to calculate indices into that allocated
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memory, so if these values are incorrect that can lead to potential
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unbounded memory allocation, or invalid memory accesses.
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Also, the allocation of the pagetable is changed from g_malloc0()
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to qemu_blockalign().
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Signed-off-by: Jeff Cody <jcody@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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block/vpc.c | 27 +++++++++++++++++++++++----
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1 files changed, 23 insertions(+), 4 deletions(-)
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diff --git a/block/vpc.c b/block/vpc.c
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index 059069f..de5bc22 100644
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--- a/block/vpc.c
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+++ b/block/vpc.c
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@@ -45,6 +45,8 @@ enum vhd_type {
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// Seconds since Jan 1, 2000 0:00:00 (UTC)
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#define VHD_TIMESTAMP_BASE 946684800
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+#define VHD_MAX_SECTORS (65535LL * 255 * 255)
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+
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// always big-endian
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struct vhd_footer {
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char creator[8]; // "conectix"
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@@ -164,6 +166,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
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struct vhd_dyndisk_header* dyndisk_header;
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uint8_t buf[HEADER_SIZE];
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uint32_t checksum;
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+ uint64_t computed_size;
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int disk_type = VHD_DYNAMIC;
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int ret;
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@@ -212,7 +215,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
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be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
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/* Allow a maximum disk size of approximately 2 TB */
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- if (bs->total_sectors >= 65535LL * 255 * 255) {
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+ if (bs->total_sectors >= VHD_MAX_SECTORS) {
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ret = -EFBIG;
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goto fail;
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}
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@@ -235,7 +238,23 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
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s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
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s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
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- s->pagetable = g_malloc(s->max_table_entries * 4);
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+
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+ if ((bs->total_sectors * 512) / s->block_size > 0xffffffffU) {
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+ ret = -EINVAL;
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+ goto fail;
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+ }
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+ if (s->max_table_entries > (VHD_MAX_SECTORS * 512) / s->block_size) {
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+ ret = -EINVAL;
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+ goto fail;
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+ }
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+
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+ computed_size = (uint64_t) s->max_table_entries * s->block_size;
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+ if (computed_size < bs->total_sectors * 512) {
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+ ret = -EINVAL;
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+ goto fail;
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+ }
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+
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+ s->pagetable = qemu_blockalign(bs, s->max_table_entries * 4);
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s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
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@@ -281,7 +300,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
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return 0;
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fail:
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- g_free(s->pagetable);
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+ qemu_vfree(s->pagetable);
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#ifdef CACHE
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g_free(s->pageentry_u8);
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#endif
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@@ -804,7 +823,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options,
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static void vpc_close(BlockDriverState *bs)
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{
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BDRVVPCState *s = bs->opaque;
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- g_free(s->pagetable);
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+ qemu_vfree(s->pagetable);
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#ifdef CACHE
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g_free(s->pageentry_u8);
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#endif
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--
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1.7.1
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