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[Qemu-devel] [PATCH v2 2/3] qemu-img: Detect backing file chain infinite
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v2 2/3] qemu-img: Detect backing file chain infinite loops |
Date: |
Mon, 15 Oct 2012 14:44:16 +0200 |
A malicious or corruption image can contain an infinite loop of backing
files. The qemu-img info --backing-chain command must not hang when
such files are encountered.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
qemu-img.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/qemu-img.c b/qemu-img.c
index c717f3e..60a5cc8 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1259,6 +1259,11 @@ typedef enum OutputFormat {
OFORMAT_HUMAN,
} OutputFormat;
+static gboolean str_equal_func(gconstpointer a, gconstpointer b)
+{
+ return strcmp(a, b) == 0;
+}
+
static int img_info(int argc, char **argv)
{
int c;
@@ -1268,6 +1273,7 @@ static int img_info(int argc, char **argv)
char *filename, *fmt;
BlockDriverState *bs;
ImageInfo *info;
+ GHashTable *filenames;
fmt = NULL;
output = NULL;
@@ -1306,6 +1312,9 @@ static int img_info(int argc, char **argv)
}
filename = g_strdup(argv[optind++]);
+ filenames = g_hash_table_new_full(g_str_hash, str_equal_func,
+ g_free, NULL);
+
if (output && !strcmp(output, "json")) {
output_format = OFORMAT_JSON;
} else if (output && !strcmp(output, "human")) {
@@ -1320,6 +1329,12 @@ static int img_info(int argc, char **argv)
}
do {
+ if (g_hash_table_lookup_extended(filenames, filename, NULL, NULL)) {
+ error_report("Aborting due to backing file chain infinite loop.");
+ goto err;
+ }
+ g_hash_table_insert(filenames, g_strdup(filename), NULL);
+
bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING,
false);
if (!bs) {
@@ -1376,11 +1391,13 @@ static int img_info(int argc, char **argv)
if (chain && output_format == OFORMAT_JSON) {
printf("]\n");
}
+ g_hash_table_destroy(filenames);
return 0;
err:
g_free(filename);
g_free(fmt);
+ g_hash_table_destroy(filenames);
return 1;
}
--
1.7.11.7