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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 12/12] xenstore: handle memory allocation failures in xenstored
Check for failures when allocating new memory in xenstored.
Unfortunately there are several conditions which might render those
checks void: It might be impossible to send an "ENOMEM" response as
this requires allocating some memory.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
tools/xenstore/xenstored_core.c | 185 ++++++++++++++++++++++++++-------
tools/xenstore/xenstored_domain.c | 10 ++
tools/xenstore/xenstored_transaction.c | 20 ++++
tools/xenstore/xenstored_watch.c | 12 +++
4 files changed, 187 insertions(+), 40 deletions(-)
diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index f89a636..d880afa 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -149,8 +149,10 @@ void trace(const char *fmt, ...)
va_start(arglist, fmt);
str = talloc_vasprintf(NULL, fmt, arglist);
va_end(arglist);
- dummy = write(tracefd, str, strlen(str));
- talloc_free(str);
+ if (str) {
+ dummy = write(tracefd, str, strlen(str));
+ talloc_free(str);
+ }
}
static void trace_io(const struct connection *conn,
@@ -392,7 +394,16 @@ static struct node *read_node(struct connection *conn,
const void *ctx,
}
node = talloc(ctx, struct node);
+ if (!node) {
+ errno = ENOMEM;
+ return NULL;
+ }
node->name = talloc_strdup(node, name);
+ if (!node->name) {
+ talloc_free(node);
+ errno = ENOMEM;
+ return NULL;
+ }
node->parent = NULL;
node->tdb = tdb_context(conn);
talloc_steal(node, data.dptr);
@@ -490,35 +501,46 @@ static enum xs_perm_type perm_for_conn(struct connection
*conn,
*/
static char *get_parent(const void *ctx, const char *node)
{
+ char *parent;
char *slash = strrchr(node + 1, '/');
- if (!slash)
- return talloc_strdup(ctx, "/");
- return talloc_asprintf(ctx, "%.*s", (int)(slash - node), node);
+
+ parent = slash ? talloc_asprintf(ctx, "%.*s", (int)(slash - node), node)
+ : talloc_strdup(ctx, "/");
+ if (!parent)
+ errno = ENOMEM;
+
+ return parent;
}
/*
* What do parents say?
* Temporary memory allocations are done with ctx.
*/
-static enum xs_perm_type ask_parents(struct connection *conn, const void *ctx,
- const char *name)
+static int ask_parents(struct connection *conn, const void *ctx,
+ const char *name, enum xs_perm_type *perm)
{
struct node *node;
do {
name = get_parent(ctx, name);
+ if (!name)
+ return errno;
node = read_node(conn, ctx, name);
if (node)
break;
+ if (errno == ENOMEM)
+ return errno;
} while (!streq(name, "/"));
/* No permission at root? We're in trouble. */
if (!node) {
corrupt(conn, "No permissions file at root");
- return XS_PERM_NONE;
+ *perm = XS_PERM_NONE;
+ return 0;
}
- return perm_for_conn(conn, node->perms, node->num_perms);
+ *perm = perm_for_conn(conn, node->perms, node->num_perms);
+ return 0;
}
/*
@@ -532,11 +554,15 @@ static int errno_from_parents(struct connection *conn,
const void *ctx,
const char *node, int errnum,
enum xs_perm_type perm)
{
+ enum xs_perm_type parent_perm = XS_PERM_NONE;
+
/* We always tell them about memory failures. */
if (errnum == ENOMEM)
return errnum;
- if (ask_parents(conn, ctx, node) & perm)
+ if (ask_parents(conn, ctx, node, &parent_perm))
+ return errno;
+ if (parent_perm & perm)
return errnum;
return EACCES;
}
@@ -566,7 +592,7 @@ struct node *get_node(struct connection *conn,
}
}
/* Clean up errno if they weren't supposed to know. */
- if (!node)
+ if (!node && errno != ENOMEM)
errno = errno_from_parents(conn, ctx, name, errno, perm);
return node;
}
@@ -656,11 +682,29 @@ void send_reply(struct connection *conn, enum
xsd_sockmsg_type type,
} else {
/* Message is a child of the connection for auto-cleanup. */
bdata = new_buffer(conn);
+
+ /*
+ * Allocation failure here is unfortunate: we have no way to
+ * tell anybody about it.
+ */
+ if (!bdata)
+ return;
}
if (len <= DEFAULT_BUFFER_SIZE)
bdata->buffer = bdata->default_buffer;
else
bdata->buffer = talloc_array(bdata, char, len);
+ if (!bdata->buffer) {
+ if (type == XS_WATCH_EVENT) {
+ /* Same as above: no way to tell someone. */
+ talloc_free(bdata);
+ return;
+ }
+ /* re-establish request buffer for sending ENOMEM. */
+ conn->in = bdata;
+ send_error(conn, ENOMEM);
+ return;
+ }
/* Update relevant header fields and fill in the message body. */
bdata->hdr.msg.type = type;
@@ -669,6 +713,8 @@ void send_reply(struct connection *conn, enum
xsd_sockmsg_type type,
/* Queue for later transmission. */
list_add_tail(&bdata->list, &conn->out_list);
+
+ return;
}
/* Some routines (write, mkdir, etc) just need a non-error return */
@@ -730,6 +776,8 @@ static char *perms_to_strings(const void *ctx,
strings = talloc_realloc(ctx, strings, char,
*len + strlen(buffer) + 1);
+ if (!strings)
+ return NULL;
strcpy(strings + *len, buffer);
*len += strlen(buffer) + 1;
}
@@ -876,6 +924,9 @@ static struct node *construct_node(struct connection *conn,
const void *ctx,
struct node *parent, *node;
char *children, *parentname = get_parent(ctx, name);
+ if (!parentname)
+ return NULL;
+
/* If parent doesn't exist, create it. */
parent = read_node(conn, parentname, parentname);
if (!parent)
@@ -1086,9 +1137,15 @@ static int _rm(struct connection *conn, const void *ctx,
struct node *node,
/* Delete from parent first, then if we crash, the worst that can
happen is the child will continue to take up space, but will
otherwise be unreachable. */
- struct node *parent = read_node(conn, ctx, get_parent(ctx, name));
+ struct node *parent;
+ char *parentname = get_parent(ctx, name);
+
+ if (!parentname)
+ return errno;
+
+ parent = read_node(conn, ctx, parentname);
if (!parent)
- return EINVAL;
+ return (errno == ENOMEM) ? ENOMEM : EINVAL;
if (!delete_child(conn, parent, basename(name)))
return EINVAL;
@@ -1114,19 +1171,24 @@ static int do_rm(struct connection *conn, struct
buffered_data *in)
struct node *node;
int ret;
char *name;
+ char *parentname;
node = get_node_canonicalized(conn, in, onearg(in), &name,
XS_PERM_WRITE);
if (!node) {
/* Didn't exist already? Fine, if parent exists. */
if (errno == ENOENT) {
- node = read_node(conn, in, get_parent(in, name));
+ parentname = get_parent(in, name);
+ if (!parentname)
+ return errno;
+ node = read_node(conn, in, parentname);
if (node) {
send_ack(conn, XS_RM);
return 0;
}
/* Restore errno, just in case. */
- errno = ENOENT;
+ if (errno != ENOMEM)
+ errno = ENOENT;
}
return errno;
}
@@ -1186,6 +1248,8 @@ static int do_set_perms(struct connection *conn, struct
buffered_data *in)
num--;
perms = talloc_array(node, struct xs_permissions, num);
+ if (!perms)
+ return ENOMEM;
if (!xs_strings_to_perms(perms, num, permstr))
return errno;
@@ -1319,7 +1383,7 @@ static void handle_input(struct connection *conn)
if (!conn->in) {
conn->in = new_buffer(conn);
- /* In case of no memory just try it next time again. */
+ /* In case of no memory just try it again next time. */
if (!conn->in)
return;
}
@@ -1327,26 +1391,29 @@ static void handle_input(struct connection *conn)
/* Not finished header yet? */
if (in->inhdr) {
- bytes = conn->read(conn, in->hdr.raw + in->used,
- sizeof(in->hdr) - in->used);
- if (bytes < 0)
- goto bad_client;
- in->used += bytes;
- if (in->used != sizeof(in->hdr))
- return;
+ if (in->used != sizeof(in->hdr)) {
+ bytes = conn->read(conn, in->hdr.raw + in->used,
+ sizeof(in->hdr) - in->used);
+ if (bytes < 0)
+ goto bad_client;
+ in->used += bytes;
+ if (in->used != sizeof(in->hdr))
+ return;
- if (in->hdr.msg.len > XENSTORE_PAYLOAD_MAX) {
- syslog(LOG_ERR, "Client tried to feed us %i",
- in->hdr.msg.len);
- goto bad_client;
+ if (in->hdr.msg.len > XENSTORE_PAYLOAD_MAX) {
+ syslog(LOG_ERR, "Client tried to feed us %i",
+ in->hdr.msg.len);
+ goto bad_client;
+ }
}
if (in->hdr.msg.len <= DEFAULT_BUFFER_SIZE)
in->buffer = in->default_buffer;
else
in->buffer = talloc_array(in, char, in->hdr.msg.len);
+ /* In case of no memory just try it again next time. */
if (!in->buffer)
- goto bad_client;
+ return;
in->used = 0;
in->inhdr = false;
}
@@ -1469,6 +1536,9 @@ static void manual_node(const char *name, const char
*child)
struct xs_permissions perms = { .id = 0, .perms = XS_PERM_NONE };
node = talloc_zero(NULL, struct node);
+ if (!node)
+ barf_perror("Could not allocate initial node %s", name);
+
node->name = name;
node->perms = &perms;
node->num_perms = 1;
@@ -1506,6 +1576,8 @@ static void setup_structure(void)
{
char *tdbname;
tdbname = talloc_strdup(talloc_autofree_context(), xs_daemon_tdb());
+ if (!tdbname)
+ barf_perror("Could not create tdbname");
if (!(tdb_flags & TDB_INTERNAL))
tdb_ctx = tdb_open_ex(tdbname, 0, tdb_flags, O_RDWR, 0,
@@ -1584,11 +1656,14 @@ static char *child_name(const char *s1, const char *s2)
}
-static void remember_string(struct hashtable *hash, const char *str)
+static int remember_string(struct hashtable *hash, const char *str)
{
char *k = malloc(strlen(str) + 1);
+
+ if (!k)
+ return 0;
strcpy(k, str);
- hashtable_insert(hash, k, (void *)1);
+ return hashtable_insert(hash, k, (void *)1);
}
@@ -1615,14 +1690,23 @@ static void check_store_(const char *name, struct
hashtable *reachable)
struct hashtable * children =
create_hashtable(16, hash_from_key_fn, keys_equal_fn);
- remember_string(reachable, name);
+ if (!remember_string(reachable, name)) {
+ hashtable_destroy(children, 0);
+ log("check_store: ENOMEM");
+ return;
+ }
while (i < node->childlen) {
+ struct node *childnode;
size_t childlen = strlen(node->children + i);
char * childname = child_name(node->name,
node->children + i);
- struct node *childnode = read_node(NULL, childname,
- childname);
+
+ if (!childname) {
+ log("check_store: ENOMEM");
+ break;
+ }
+ childnode = read_node(NULL, childname, childname);
if (childnode) {
if (hashtable_search(children, childname)) {
@@ -1636,11 +1720,16 @@ static void check_store_(const char *name, struct
hashtable *reachable)
}
}
else {
- remember_string(children, childname);
+ if (!remember_string(children,
+ childname)) {
+ log("check_store: ENOMEM");
+ talloc_free(childnode);
+ talloc_free(childname);
+ break;
+ }
check_store_(childname, reachable);
}
- }
- else {
+ } else if (errno != ENOMEM) {
log("check_store: No child '%s' found!\n",
childname);
@@ -1648,7 +1737,8 @@ static void check_store_(const char *name, struct
hashtable *reachable)
remove_child_entry(NULL, node, i);
i -= childlen + 1;
}
- }
+ } else
+ log("check_store: ENOMEM");
talloc_free(childnode);
talloc_free(childname);
@@ -1658,14 +1748,15 @@ static void check_store_(const char *name, struct
hashtable *reachable)
hashtable_destroy(children, 0 /* Don't free values (they are
all (void *)1) */);
talloc_free(node);
- }
- else {
+ } else if (errno != ENOMEM) {
/* Impossible, because no database should ever be without the
root, and otherwise, we've just checked in our caller
(which made a recursive call to get here). */
log("check_store: No child '%s' found: impossible!", name);
- }
+ } else
+ log("check_store: ENOMEM");
+
}
@@ -1678,6 +1769,11 @@ static int clean_store_(TDB_CONTEXT *tdb, TDB_DATA key,
TDB_DATA val,
struct hashtable *reachable = private;
char * name = talloc_strndup(NULL, key.dptr, key.dsize);
+ if (!name) {
+ log("clean_store: ENOMEM");
+ return 1;
+ }
+
if (!hashtable_search(reachable, name)) {
log("clean_store: '%s' is orphaned!", name);
if (recovery) {
@@ -1707,6 +1803,11 @@ static void check_store(void)
struct hashtable * reachable =
create_hashtable(16, hash_from_key_fn, keys_equal_fn);
+ if (!reachable) {
+ log("check_store: ENOMEM");
+ return;
+ }
+
log("Checking store ...");
check_store_(root, reachable);
clean_store(reachable);
@@ -1763,10 +1864,14 @@ static void init_sockets(int **psock, int **pro_sock)
/* Create sockets for them to listen to. */
*psock = sock = talloc(talloc_autofree_context(), int);
+ if (!sock)
+ barf_perror("No memory when creating sockets");
*sock = socket(PF_UNIX, SOCK_STREAM, 0);
if (*sock < 0)
barf_perror("Could not create socket");
*pro_sock = ro_sock = talloc(talloc_autofree_context(), int);
+ if (!ro_sock)
+ barf_perror("No memory when creating sockets");
*ro_sock = socket(PF_UNIX, SOCK_STREAM, 0);
if (*ro_sock < 0)
barf_perror("Could not create socket");
diff --git a/tools/xenstore/xenstored_domain.c
b/tools/xenstore/xenstored_domain.c
index fefed5e..5322280 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -279,10 +279,15 @@ static struct domain *new_domain(void *context, unsigned
int domid,
int rc;
domain = talloc(context, struct domain);
+ if (!domain)
+ return NULL;
+
domain->port = 0;
domain->shutdown = 0;
domain->domid = domid;
domain->path = talloc_domain_path(domain, domid);
+ if (!domain->path)
+ return NULL;
list_add(&domain->list, &domains);
talloc_set_destructor(domain, destroy_domain);
@@ -294,6 +299,9 @@ static struct domain *new_domain(void *context, unsigned
int domid,
domain->port = rc;
domain->conn = new_connection(writechn, readchn);
+ if (!domain->conn)
+ return NULL;
+
domain->conn->domain = domain;
domain->conn->id = domid;
@@ -498,6 +506,8 @@ int do_get_domain_path(struct connection *conn, struct
buffered_data *in)
return EINVAL;
path = talloc_domain_path(conn, atoi(domid_str));
+ if (!path)
+ return errno;
send_reply(conn, XS_GET_DOMAIN_PATH, path, strlen(path) + 1);
diff --git a/tools/xenstore/xenstored_transaction.c
b/tools/xenstore/xenstored_transaction.c
index d314cd5..ff05f95 100644
--- a/tools/xenstore/xenstored_transaction.c
+++ b/tools/xenstore/xenstored_transaction.c
@@ -119,6 +119,11 @@ void add_change_node(struct connection *conn, struct node
*node, bool recurse)
}
i = talloc(trans, struct changed_node);
+ if (!i) {
+ /* All we can do is let the transaction fail. */
+ generation++;
+ return;
+ }
i->node = talloc_strdup(i, node->name);
i->recurse = recurse;
list_add_tail(&i->list, &trans->changes);
@@ -163,11 +168,16 @@ int do_transaction_start(struct connection *conn, struct
buffered_data *in)
/* Attach transaction to input for autofree until it's complete */
trans = talloc_zero(in, struct transaction);
+ if (!trans)
+ return ENOMEM;
+
INIT_LIST_HEAD(&trans->changes);
INIT_LIST_HEAD(&trans->changed_domains);
trans->generation = generation;
trans->tdb_name = talloc_asprintf(trans, "%s.%p",
xs_daemon_tdb(), trans);
+ if (!trans->tdb_name)
+ return ENOMEM;
trans->tdb = tdb_copy(tdb_context(conn), trans->tdb_name);
if (!trans->tdb)
return errno;
@@ -246,6 +256,11 @@ void transaction_entry_inc(struct transaction *trans,
unsigned int domid)
}
d = talloc(trans, struct changed_domain);
+ if (!d) {
+ /* Let the transaction fail. */
+ generation++;
+ return;
+ }
d->domid = domid;
d->nbentry = 1;
list_add_tail(&d->list, &trans->changed_domains);
@@ -262,6 +277,11 @@ void transaction_entry_dec(struct transaction *trans,
unsigned int domid)
}
d = talloc(trans, struct changed_domain);
+ if (!d) {
+ /* Let the transaction fail. */
+ generation++;
+ return;
+ }
d->domid = domid;
d->nbentry = -1;
list_add_tail(&d->list, &trans->changed_domains);
diff --git a/tools/xenstore/xenstored_watch.c b/tools/xenstore/xenstored_watch.c
index 94251db..0dc5a40 100644
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -111,6 +111,8 @@ static void add_event(struct connection *conn,
len = strlen(name) + 1 + strlen(watch->token) + 1;
data = talloc_array(ctx, char, len);
+ if (!data)
+ return;
strcpy(data, name);
strcpy(data + strlen(name) + 1, watch->token);
send_reply(conn, XS_WATCH_EVENT, data, len);
@@ -165,6 +167,8 @@ int do_watch(struct connection *conn, struct buffered_data
*in)
} else {
relative = !strstarts(vec[0], "/");
vec[0] = canonicalize(conn, in, vec[0]);
+ if (!vec[0])
+ return ENOMEM;
if (!is_valid_nodename(vec[0]))
return EINVAL;
}
@@ -180,8 +184,14 @@ int do_watch(struct connection *conn, struct buffered_data
*in)
return E2BIG;
watch = talloc(conn, struct watch);
+ if (!watch)
+ return ENOMEM;
watch->node = talloc_strdup(watch, vec[0]);
watch->token = talloc_strdup(watch, vec[1]);
+ if (!watch->node || !watch->token) {
+ talloc_free(watch);
+ return ENOMEM;
+ }
if (relative)
watch->relative_path = get_implicit_path(conn);
else
@@ -210,6 +220,8 @@ int do_unwatch(struct connection *conn, struct
buffered_data *in)
return EINVAL;
node = canonicalize(conn, in, vec[0]);
+ if (!node)
+ return ENOMEM;
list_for_each_entry(watch, &conn->watches, list) {
if (streq(watch->node, node) && streq(watch->token, vec[1])) {
list_del(&watch->list);
--
2.6.6
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