[Xen-devel] [Patch v2 3/4] tools/xenstored: Avoid buffer overflows while setting up sockets

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Coverity ID: 1055996 1056002

Cache the xs_daemon_socket{,_ro}() strings to save pointlessly
re-snprintf()'ing the same path, and add explicit size checks against
addr.sun_path before strcpy()'ing into it.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Matthew Daley <mattd@xxxxxxxxxxx>

---
Changes in v2:
 * Use logic similar to f220279c14
---
 tools/xenstore/xenstored_core.c |   27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index ccfdaa3..2324e53 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -1718,6 +1718,9 @@ static void init_sockets(int **psock, int **pro_sock)
 {
        struct sockaddr_un addr;
        int *sock, *ro_sock;
+       const char *soc_str = xs_daemon_socket();
+       const char *soc_str_ro = xs_daemon_socket_ro();
+
        /* Create sockets for them to listen to. */
        *psock = sock = talloc(talloc_autofree_context(), int);
        *sock = socket(PF_UNIX, SOCK_STREAM, 0);
@@ -1731,19 +1734,25 @@ static void init_sockets(int **psock, int **pro_sock)
        talloc_set_destructor(ro_sock, destroy_fd);
 
        /* FIXME: Be more sophisticated, don't mug running daemon. */
-       unlink(xs_daemon_socket());
-       unlink(xs_daemon_socket_ro());
+       unlink(soc_str);
+       unlink(soc_str_ro);
 
        addr.sun_family = AF_UNIX;
-       strcpy(addr.sun_path, xs_daemon_socket());
+
+       if(strlen(soc_str) >= sizeof(addr.sun_path))
+               barf_perror("socket string '%s' too long", soc_str);
+       strcpy(addr.sun_path, soc_str);
        if (bind(*sock, (struct sockaddr *)&addr, sizeof(addr)) != 0)
-               barf_perror("Could not bind socket to %s", xs_daemon_socket());
-       strcpy(addr.sun_path, xs_daemon_socket_ro());
+               barf_perror("Could not bind socket to %s", soc_str);
+
+       if(strlen(soc_str_ro) >= sizeof(addr.sun_path))
+               barf_perror("socket string '%s' too long", soc_str_ro);
+       strcpy(addr.sun_path, soc_str_ro);
        if (bind(*ro_sock, (struct sockaddr *)&addr, sizeof(addr)) != 0)
-               barf_perror("Could not bind socket to %s",
-                           xs_daemon_socket_ro());
-       if (chmod(xs_daemon_socket(), 0600) != 0
-           || chmod(xs_daemon_socket_ro(), 0660) != 0)
+               barf_perror("Could not bind socket to %s", soc_str_ro);
+
+       if (chmod(soc_str, 0600) != 0
+           || chmod(soc_str_ro, 0660) != 0)
                barf_perror("Could not chmod sockets");
 
        if (listen(*sock, 1) != 0
-- 
1.7.10.4


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