* [Qemu-devel] [PATCH 1/2] qcow2: Catch some L1 table index overflows
2013-05-14 14:54 [Qemu-devel] [PULL for-1.5 0/2] Block patches for QEMU 1.5 Stefan Hajnoczi
@ 2013-05-14 14:54 ` Stefan Hajnoczi
2013-05-14 14:54 ` [Qemu-devel] [PATCH 2/2] block: Add hint to -EFBIG error message Stefan Hajnoczi
1 sibling, 0 replies; 3+ messages in thread
From: Stefan Hajnoczi @ 2013-05-14 14:54 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, Anthony Liguori, Stefan Hajnoczi
From: Kevin Wolf <kwolf@redhat.com>
This catches the situation that is described in the bug report at
https://bugs.launchpad.net/qemu/+bug/865518 and goes like this:
$ qemu-img create -f qcow2 huge.qcow2 $((1024*1024))T
Formatting 'huge.qcow2', fmt=qcow2 size=1152921504606846976 encryption=off cluster_size=65536 lazy_refcounts=off
$ qemu-io /tmp/huge.qcow2 -c "write $((1024*1024*1024*1024*1024*1024 - 1024)) 512"
Segmentation fault
With this patch applied the segfault will be avoided, however the case
will still fail, though gracefully:
$ qemu-img create -f qcow2 /tmp/huge.qcow2 $((1024*1024))T
Formatting 'huge.qcow2', fmt=qcow2 size=1152921504606846976 encryption=off cluster_size=65536 lazy_refcounts=off
qemu-img: The image size is too large for file format 'qcow2'
Note that even long before these overflow checks kick in, you get
insanely high memory usage (up to INT_MAX * sizeof(uint64_t) = 16 GB for
the L1 table), so with somewhat smaller image sizes you'll probably see
qemu aborting for a failed g_malloc().
If you need huge image sizes, you should increase the cluster size to
the maximum of 2 MB in order to get higher limits.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block/qcow2-cluster.c | 23 +++++++++++++++--------
block/qcow2.c | 13 +++++++++++--
block/qcow2.h | 5 +++--
3 files changed, 29 insertions(+), 12 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index c71470a..76f30e5 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -29,12 +29,13 @@
#include "block/qcow2.h"
#include "trace.h"
-int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size)
+int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
+ bool exact_size)
{
BDRVQcowState *s = bs->opaque;
- int new_l1_size, new_l1_size2, ret, i;
+ int new_l1_size2, ret, i;
uint64_t *new_l1_table;
- int64_t new_l1_table_offset;
+ int64_t new_l1_table_offset, new_l1_size;
uint8_t data[12];
if (min_size <= s->l1_size)
@@ -53,8 +54,13 @@ int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size)
}
}
+ if (new_l1_size > INT_MAX) {
+ return -EFBIG;
+ }
+
#ifdef DEBUG_ALLOC2
- fprintf(stderr, "grow l1_table from %d to %d\n", s->l1_size, new_l1_size);
+ fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n",
+ s->l1_size, new_l1_size);
#endif
new_l1_size2 = sizeof(uint64_t) * new_l1_size;
@@ -391,8 +397,8 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
int *num, uint64_t *cluster_offset)
{
BDRVQcowState *s = bs->opaque;
- unsigned int l1_index, l2_index;
- uint64_t l2_offset, *l2_table;
+ unsigned int l2_index;
+ uint64_t l1_index, l2_offset, *l2_table;
int l1_bits, c;
unsigned int index_in_cluster, nb_clusters;
uint64_t nb_available, nb_needed;
@@ -507,8 +513,8 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
int *new_l2_index)
{
BDRVQcowState *s = bs->opaque;
- unsigned int l1_index, l2_index;
- uint64_t l2_offset;
+ unsigned int l2_index;
+ uint64_t l1_index, l2_offset;
uint64_t *l2_table = NULL;
int ret;
@@ -522,6 +528,7 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
}
}
+ assert(l1_index < s->l1_size);
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
/* seek the l2 table of the given l2 offset */
diff --git a/block/qcow2.c b/block/qcow2.c
index 2e346d8..0fa5cb2 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -307,6 +307,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags)
QemuOpts *opts;
Error *local_err = NULL;
uint64_t ext_end;
+ uint64_t l1_vm_state_index;
ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
if (ret < 0) {
@@ -424,7 +425,14 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags)
/* read the level 1 table */
s->l1_size = header.l1_size;
- s->l1_vm_state_index = size_to_l1(s, header.size);
+
+ l1_vm_state_index = size_to_l1(s, header.size);
+ if (l1_vm_state_index > INT_MAX) {
+ ret = -EFBIG;
+ goto fail;
+ }
+ s->l1_vm_state_index = l1_vm_state_index;
+
/* the L1 table must contain at least enough entries to put
header.size bytes */
if (s->l1_size < s->l1_vm_state_index) {
@@ -1480,7 +1488,8 @@ static coroutine_fn int qcow2_co_discard(BlockDriverState *bs,
static int qcow2_truncate(BlockDriverState *bs, int64_t offset)
{
BDRVQcowState *s = bs->opaque;
- int ret, new_l1_size;
+ int64_t new_l1_size;
+ int ret;
if (offset & 511) {
error_report("The new size must be a multiple of 512");
diff --git a/block/qcow2.h b/block/qcow2.h
index 9421843..6959c6a 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -284,7 +284,7 @@ static inline int size_to_clusters(BDRVQcowState *s, int64_t size)
return (size + (s->cluster_size - 1)) >> s->cluster_bits;
}
-static inline int size_to_l1(BDRVQcowState *s, int64_t size)
+static inline int64_t size_to_l1(BDRVQcowState *s, int64_t size)
{
int shift = s->cluster_bits + s->l2_bits;
return (size + (1ULL << shift) - 1) >> shift;
@@ -360,7 +360,8 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix);
/* qcow2-cluster.c functions */
-int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size);
+int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
+ bool exact_size);
void qcow2_l2_cache_reset(BlockDriverState *bs);
int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
--
1.8.1.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* [Qemu-devel] [PATCH 2/2] block: Add hint to -EFBIG error message
2013-05-14 14:54 [Qemu-devel] [PULL for-1.5 0/2] Block patches for QEMU 1.5 Stefan Hajnoczi
2013-05-14 14:54 ` [Qemu-devel] [PATCH 1/2] qcow2: Catch some L1 table index overflows Stefan Hajnoczi
@ 2013-05-14 14:54 ` Stefan Hajnoczi
1 sibling, 0 replies; 3+ messages in thread
From: Stefan Hajnoczi @ 2013-05-14 14:54 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, Anthony Liguori, Stefan Hajnoczi
From: Kevin Wolf <kwolf@redhat.com>
The limit of qcow2 files at least depends on the cluster size. If the
image format has a cluster_size option, suggest to increase it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/block.c b/block.c
index aa9a533..3f87489 100644
--- a/block.c
+++ b/block.c
@@ -4857,8 +4857,12 @@ void bdrv_img_create(const char *filename, const char *fmt,
error_setg(errp,"Formatting or formatting option not supported for "
"file format '%s'", fmt);
} else if (ret == -EFBIG) {
- error_setg(errp, "The image size is too large for file format '%s'",
- fmt);
+ const char *cluster_size_hint = "";
+ if (get_option_parameter(create_options, BLOCK_OPT_CLUSTER_SIZE)) {
+ cluster_size_hint = " (try using a larger cluster size)";
+ }
+ error_setg(errp, "The image size is too large for file format '%s'%s",
+ fmt, cluster_size_hint);
} else {
error_setg(errp, "%s: error while creating %s: %s", filename, fmt,
strerror(-ret));
--
1.8.1.4
^ permalink raw reply related [flat|nested] 3+ messages in thread