xl: Do not leak events when a domain exits.

The goto in both of these places misses the event free which would
normally clean up.

==8655== 80 bytes in 1 blocks are definitely lost in loss record 1 of 1
==8655==    at 0x4024370: calloc (vg_replace_malloc.c:593)
==8655==    by 0x406EAAE: libxl__zalloc (libxl_internal.c:83)
==8655==    by 0x4078173: libxl__event_new (libxl_event.c:1167)
==8655==    by 0x4056373: domain_death_occurred (libxl.c:958)
==8655==    by 0x4058D06: domain_death_xswatch_callback (libxl.c:1038)
==8655==    by 0x4078EB5: watchfd_callback (libxl_event.c:458)
==8655==    by 0x407839E: afterpoll_internal (libxl_event.c:949)
==8655==    by 0x4079142: eventloop_iteration (libxl_event.c:1371)
==8655==    by 0x40799BB: libxl_event_wait (libxl_event.c:1396)
==8655==    by 0x805CC67: create_domain (xl_cmdimpl.c:1698)
==8655==    by 0x805E001: main_create (xl_cmdimpl.c:3986)
==8655==    by 0x804D43D: main (xl.c:285)


Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

stubdom/grub/kexec.c

@@ -137,6 +137,10 @@ void kexec(void *kernel, long kernel_size, void *module, long module_size, char
     dom = xc_dom_allocate(xc_handle, cmdline, features);
     dom->allocate = kexec_allocate;
 
+    /* We are using guest owned memory, therefore no limits. */
+    xc_dom_kernel_max_size(dom, 0);
+    xc_dom_ramdisk_max_size(dom, 0);
+
     dom->kernel_blob = kernel;
     dom->kernel_size = kernel_size;
 

tools/libxc/xc_dom.h

@@ -55,6 +55,9 @@ struct xc_dom_image {
     void *ramdisk_blob;
     size_t ramdisk_size;
 
+    size_t max_kernel_size;
+    size_t max_ramdisk_size;
+
     /* arguments and parameters */
     char *cmdline;
     uint32_t f_requested[XENFEAT_NR_SUBMAPS];
@@ -194,6 +197,13 @@ void xc_dom_release_phys(struct xc_dom_image *dom);
 void xc_dom_release(struct xc_dom_image *dom);
 int xc_dom_mem_init(struct xc_dom_image *dom, unsigned int mem_mb);
 
+#define XC_DOM_DECOMPRESS_MAX (1024*1024*1024) /* 1GB */
+int xc_dom_kernel_check_size(struct xc_dom_image *dom, size_t sz);
+int xc_dom_kernel_max_size(struct xc_dom_image *dom, size_t sz);
+
+int xc_dom_ramdisk_check_size(struct xc_dom_image *dom, size_t sz);
+int xc_dom_ramdisk_max_size(struct xc_dom_image *dom, size_t sz);
+
 size_t xc_dom_check_gzip(xc_interface *xch,
                      void *blob, size_t ziplen);
 int xc_dom_do_gunzip(xc_interface *xch,
@@ -254,7 +264,8 @@ void xc_dom_log_memory_footprint(struct xc_dom_image *dom);
 void *xc_dom_malloc(struct xc_dom_image *dom, size_t size);
 void *xc_dom_malloc_page_aligned(struct xc_dom_image *dom, size_t size);
 void *xc_dom_malloc_filemap(struct xc_dom_image *dom,
-                            const char *filename, size_t * size);
+                            const char *filename, size_t * size,
+                            const size_t max_size);
 char *xc_dom_strdup(struct xc_dom_image *dom, const char *str);
 
 /* --- alloc memory pool ------------------------------------------- */

tools/libxc/xc_dom_bzimageloader.c

@@ -47,7 +47,7 @@ static int xc_try_bzip2_decode(
     char *out_buf;
     char *tmp_buf;
     int retval = -1;
-    int outsize;
+    unsigned int outsize;
     uint64_t total;
 
     stream.bzalloc = NULL;
@@ -79,6 +79,17 @@ static int xc_try_bzip2_decode(
     stream.next_out = out_buf;
     stream.avail_out = dom->kernel_size;
 
+    /*
+     * stream.avail_in is an unsigned int, while kernel_size is a
+     * size_t. Check we aren't overflowing.
+     */
+    if ( stream.avail_in != dom->kernel_size )
+    {
+        DOMPRINTF("BZIP2: Input too large");
+        free(out_buf);
+        goto bzip2_cleanup;
+    }
+
     for ( ; ; )
     {
         ret = BZ2_bzDecompress(&stream);
@@ -98,13 +109,20 @@ static int xc_try_bzip2_decode(
         if ( stream.avail_out == 0 )
         {
             /* Protect against output buffer overflow */
-            if ( outsize > INT_MAX / 2 )
+            if ( outsize > UINT_MAX / 2 )
             {
                 DOMPRINTF("BZIP2: output buffer overflow");
                 free(out_buf);
                 goto bzip2_cleanup;
             }
 
+            if ( xc_dom_kernel_check_size(dom, outsize * 2) )
+            {
+                DOMPRINTF("BZIP2: output too large");
+                free(out_buf);
+                goto bzip2_cleanup;
+            }
+
             tmp_buf = realloc(out_buf, outsize * 2);
             if ( tmp_buf == NULL )
             {
@@ -172,7 +190,7 @@ static int _xc_try_lzma_decode(
     unsigned char *out_buf;
     unsigned char *tmp_buf;
     int retval = -1;
-    int outsize;
+    size_t outsize;
     const char *msg;
 
     /* sigh.  We don't know up-front how much memory we are going to need
@@ -244,13 +262,20 @@ static int _xc_try_lzma_decode(
         if ( stream->avail_out == 0 )
         {
             /* Protect against output buffer overflow */
-            if ( outsize > INT_MAX / 2 )
+            if ( outsize > SIZE_MAX / 2 )
             {
                 DOMPRINTF("%s: output buffer overflow", what);
                 free(out_buf);
                 goto lzma_cleanup;
             }
 
+            if ( xc_dom_kernel_check_size(dom, outsize * 2) )
+            {
+                DOMPRINTF("%s: output too large", what);
+                free(out_buf);
+                goto lzma_cleanup;
+            }
+
             tmp_buf = realloc(out_buf, outsize * 2);
             if ( tmp_buf == NULL )
             {
@@ -359,6 +384,12 @@ static int xc_try_lzo1x_decode(
         0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a
     };
 
+    /*
+     * lzo_uint should match size_t. Check that this is the case to be
+     * sure we won't overflow various lzo_uint fields.
+     */
+    XC_BUILD_BUG_ON(sizeof(lzo_uint) != sizeof(size_t));
+
     ret = lzo_init();
     if ( ret != LZO_E_OK )
     {
@@ -438,6 +469,14 @@ static int xc_try_lzo1x_decode(
         if ( src_len <= 0 || src_len > dst_len || src_len > left )
             break;
 
+        msg = "Output buffer overflow";
+        if ( *size > SIZE_MAX - dst_len )
+            break;
+
+        msg = "Decompressed image too large";
+        if ( xc_dom_kernel_check_size(dom, *size + dst_len) )
+            break;
+
         msg = "Failed to (re)alloc memory";
         tmp_buf = realloc(out_buf, *size + dst_len);
         if ( tmp_buf == NULL )

tools/libxc/xc_dom_core.c

@@ -159,7 +159,8 @@ void *xc_dom_malloc_page_aligned(struct xc_dom_image *dom, size_t size)
 }
 
 void *xc_dom_malloc_filemap(struct xc_dom_image *dom,
-                            const char *filename, size_t * size)
+                            const char *filename, size_t * size,
+                            const size_t max_size)
 {
     struct xc_dom_mem *block = NULL;
     int fd = -1;
@@ -171,6 +172,13 @@ void *xc_dom_malloc_filemap(struct xc_dom_image *dom,
     lseek(fd, 0, SEEK_SET);
     *size = lseek(fd, 0, SEEK_END);
 
+    if ( max_size && *size > max_size )
+    {
+        xc_dom_panic(dom->xch, XC_OUT_OF_MEMORY,
+                     "tried to map file which is too large");
+        goto err;
+    }
+
     block = malloc(sizeof(*block));
     if ( block == NULL )
         goto err;
@@ -221,6 +229,40 @@ char *xc_dom_strdup(struct xc_dom_image *dom, const char *str)
     return nstr;
 }
 
+/* ------------------------------------------------------------------------ */
+/* decompression buffer sizing                                              */
+int xc_dom_kernel_check_size(struct xc_dom_image *dom, size_t sz)
+{
+    /* No limit */
+    if ( !dom->max_kernel_size )
+        return 0;
+
+    if ( sz > dom->max_kernel_size )
+    {
+        xc_dom_panic(dom->xch, XC_INVALID_KERNEL,
+                     "kernel image too large");
+        return 1;
+    }
+
+    return 0;
+}
+
+int xc_dom_ramdisk_check_size(struct xc_dom_image *dom, size_t sz)
+{
+    /* No limit */
+    if ( !dom->max_ramdisk_size )
+        return 0;
+
+    if ( sz > dom->max_ramdisk_size )
+    {
+        xc_dom_panic(dom->xch, XC_INVALID_KERNEL,
+                     "ramdisk image too large");
+        return 1;
+    }
+
+    return 0;
+}
+
 /* ------------------------------------------------------------------------ */
 /* read files, copy memory blocks, with transparent gunzip                  */
 
@@ -235,7 +277,7 @@ size_t xc_dom_check_gzip(xc_interface *xch, void *blob, size_t ziplen)
 
     gzlen = blob + ziplen - 4;
     unziplen = gzlen[3] << 24 | gzlen[2] << 16 | gzlen[1] << 8 | gzlen[0];
-    if ( (unziplen < 0) || (unziplen > (1024*1024*1024)) ) /* 1GB limit */
+    if ( (unziplen < 0) || (unziplen > XC_DOM_DECOMPRESS_MAX) )
     {
         xc_dom_printf
             (xch,
@@ -288,6 +330,9 @@ int xc_dom_try_gunzip(struct xc_dom_image *dom, void **blob, size_t * size)
     if ( unziplen == 0 )
         return 0;
 
+    if ( xc_dom_kernel_check_size(dom, unziplen) )
+        return 0;
+
     unzip = xc_dom_malloc(dom, unziplen);
     if ( unzip == NULL )
         return -1;
@@ -590,6 +635,9 @@ struct xc_dom_image *xc_dom_allocate(xc_interface *xch,
     memset(dom, 0, sizeof(*dom));
     dom->xch = xch;
 
+    dom->max_kernel_size = XC_DOM_DECOMPRESS_MAX;
+    dom->max_ramdisk_size = XC_DOM_DECOMPRESS_MAX;
+
     if ( cmdline )
         dom->cmdline = xc_dom_strdup(dom, cmdline);
     if ( features )
@@ -610,10 +658,25 @@ struct xc_dom_image *xc_dom_allocate(xc_interface *xch,
     return NULL;
 }
 
+int xc_dom_kernel_max_size(struct xc_dom_image *dom, size_t sz)
+{
+    DOMPRINTF("%s: kernel_max_size=%zx", __FUNCTION__, sz);
+    dom->max_kernel_size = sz;
+    return 0;
+}
+
+int xc_dom_ramdisk_max_size(struct xc_dom_image *dom, size_t sz)
+{
+    DOMPRINTF("%s: ramdisk_max_size=%zx", __FUNCTION__, sz);
+    dom->max_ramdisk_size = sz;
+    return 0;
+}
+
 int xc_dom_kernel_file(struct xc_dom_image *dom, const char *filename)
 {
     DOMPRINTF("%s: filename=\"%s\"", __FUNCTION__, filename);
-    dom->kernel_blob = xc_dom_malloc_filemap(dom, filename, &dom->kernel_size);
+    dom->kernel_blob = xc_dom_malloc_filemap(dom, filename, &dom->kernel_size,
+                                             dom->max_kernel_size);
     if ( dom->kernel_blob == NULL )
         return -1;
     return xc_dom_try_gunzip(dom, &dom->kernel_blob, &dom->kernel_size);
@@ -622,8 +685,10 @@ int xc_dom_kernel_file(struct xc_dom_image *dom, const char *filename)
 int xc_dom_ramdisk_file(struct xc_dom_image *dom, const char *filename)
 {
     DOMPRINTF("%s: filename=\"%s\"", __FUNCTION__, filename);
+    /* We do not enforce any particular size limit here */
     dom->ramdisk_blob =
-        xc_dom_malloc_filemap(dom, filename, &dom->ramdisk_size);
+        xc_dom_malloc_filemap(dom, filename, &dom->ramdisk_size, 0);
+
     if ( dom->ramdisk_blob == NULL )
         return -1;
 //    return xc_dom_try_gunzip(dom, &dom->ramdisk_blob, &dom->ramdisk_size);
@@ -783,7 +848,11 @@ int xc_dom_build_image(struct xc_dom_image *dom)
         void *ramdiskmap;
 
         unziplen = xc_dom_check_gzip(dom->xch, dom->ramdisk_blob, dom->ramdisk_size);
+        if ( xc_dom_ramdisk_check_size(dom, unziplen) != 0 )
+            unziplen = 0;
+
         ramdisklen = unziplen ? unziplen : dom->ramdisk_size;
+
         if ( xc_dom_alloc_segment(dom, &dom->ramdisk_seg, "ramdisk", 0,
                                   ramdisklen) != 0 )
             goto err;

tools/libxl/xl_cmdimpl.c

@@ -2118,6 +2118,7 @@ start:
 
             case 0:
                 LOG("Done. Exiting now");
+                libxl_event_free(ctx, event);
                 ret = 0;
                 goto out;
 
@@ -2127,6 +2128,7 @@ start:
 
         case LIBXL_EVENT_TYPE_DOMAIN_DEATH:
             LOG("Domain %d has been destroyed.", domid);
+            libxl_event_free(ctx, event);
             ret = 0;
             goto out;