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authorWaldemar Brodkorb <wbx@uclibc-ng.org>2016-08-05 19:33:44 (GMT)
committerWaldemar Brodkorb <wbx@uclibc-ng.org>2016-08-05 19:33:44 (GMT)
commit9213ad631513d0e67d9d31465c9cdb3f3dde0399 (patch)
tree046479bb8e8b66192c8227f2054e3260e3dcd483 /libc/inet
parent79dc2c282b655adb8d5075d9eb2519883042ccf8 (diff)
sunrpc: Do not use alloca in clntudp_call
CVE-2016-4429: The call is technically in a loop, and under certain circumstances (which are quite difficult to reproduce in a test case), alloca can be invoked repeatedly during a single call to clntudp_call. As a result, the available stack space can be exhausted (even though individual alloca sizes are bounded implicitly by what can fit into a UDP packet, as a side effect of the earlier successful send operation). From GNU libc: https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commit;h=bc779a1a5b3035133024b21e2f339fe4219fb11c
Diffstat (limited to 'libc/inet')
-rw-r--r--libc/inet/rpc/clnt_udp.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/libc/inet/rpc/clnt_udp.c b/libc/inet/rpc/clnt_udp.c
index 4fc55b7..ce7e9e6 100644
--- a/libc/inet/rpc/clnt_udp.c
+++ b/libc/inet/rpc/clnt_udp.c
@@ -368,9 +368,15 @@ send_again:
struct sock_extended_err *e;
struct sockaddr_in err_addr;
struct iovec iov;
- char *cbuf = (char *) alloca (outlen + 256);
+ char *cbuf = malloc (outlen + 256);
int ret;
+ if (cbuf == NULL)
+ {
+ cu->cu_error.re_errno = errno;
+ return (cu->cu_error.re_status = RPC_CANTRECV);
+ }
+
iov.iov_base = cbuf + 256;
iov.iov_len = outlen;
msg.msg_name = (void *) &err_addr;
@@ -395,10 +401,12 @@ send_again:
cmsg = CMSG_NXTHDR (&msg, cmsg))
if (cmsg->cmsg_level == SOL_IP && cmsg->cmsg_type == IP_RECVERR)
{
+ free (cbuf);
e = (struct sock_extended_err *) CMSG_DATA(cmsg);
cu->cu_error.re_errno = e->ee_errno;
return (cu->cu_error.re_status = RPC_CANTRECV);
}
+ free (cbuf);
}
#endif
do