From: Kevin Wolf Date: Wed, 26 Mar 2014 13:06:06 +0100 Subject: [PATCH] qcow2: Check maximum L1 size in qcow2_snapshot_load_tmp() (CVE-2014-0143) This avoids an unbounded allocation. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Signed-off-by: Stefan Hajnoczi (cherry picked from commit 6a83f8b5bec6f59e56cc49bd49e4c3f8f805d56f) Conflicts: block/qcow2.c tests/qemu-iotests/080 tests/qemu-iotests/080.out --- block/qcow2-snapshot.c | 4 ++++ block/qcow2.c | 4 +--- block/qcow2.h | 4 ++++ 3 files changed, 9 insertions(+), 3 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index dc8736a..d2c956c 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -622,6 +622,10 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name) sn = &s->snapshots[snapshot_index]; /* Allocate and read in the snapshot's L1 table */ + if (sn->l1_size > QCOW_MAX_L1_SIZE) { + fprintf(stderr, "Snapshot L1 table too large"); + return -EFBIG; + } new_l1_bytes = sn->l1_size * sizeof(uint64_t); new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512)); diff --git a/block/qcow2.c b/block/qcow2.c index c9beb01..5dfd5ec 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -516,9 +516,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags) } /* read the level 1 table */ - if (header.l1_size > 0x2000000) { - /* 32 MB L1 table is enough for 2 PB images at 64k cluster size - * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ + if (header.l1_size > QCOW_MAX_L1_SIZE) { fprintf(stderr, "Active L1 table too large"); ret = -EFBIG; goto fail; diff --git a/block/qcow2.h b/block/qcow2.h index baf62a0..0912488 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -44,6 +44,10 @@ * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ #define QCOW_MAX_REFTABLE_SIZE 0x800000 +/* 32 MB L1 table is enough for 2 PB images at 64k cluster size + * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ +#define QCOW_MAX_L1_SIZE 0x2000000 + /* indicate that the refcount of the referenced cluster is exactly one. */ #define QCOW_OFLAG_COPIED (1LL << 63) /* indicate that the cluster is compressed (they never have the copied flag) */