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libratbox: fix scoping issue with alloca()'d buffer which could result in undefined behaviour.

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this is ported from upstream libratbox r29267
This commit is contained in:
William Pitcock 2015-12-27 21:19:17 -06:00
parent 340b2512d4
commit 5cc7ba2577
1 changed files with 5 additions and 8 deletions
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13
libratbox/src/commio.c
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@ -2215,14 +2215,12 @@ rb_recv_fd_buf(rb_fde_t *F, void *data, size_t datasize, rb_fde_t **xF, int nfds
int int
rb_send_fd_buf(rb_fde_t *xF, rb_fde_t **F, int count, void *data, size_t datasize, pid_t pid) rb_send_fd_buf(rb_fde_t *xF, rb_fde_t **F, int count, void *data, size_t datasize, pid_t pid)
{ {
int n;
struct msghdr msg; struct msghdr msg;
struct cmsghdr *cmsg; struct cmsghdr *cmsg;
struct iovec iov[1]; struct iovec iov[1];
char empty = '0'; char empty = '0';
char *buf;
memset(&msg, 0, sizeof msg); memset(&msg, 0, sizeof(msg));
if(datasize == 0) if(datasize == 0)
{ {
iov[0].iov_base = ∅ iov[0].iov_base = ∅
@ -2243,9 +2241,8 @@ rb_send_fd_buf(rb_fde_t *xF, rb_fde_t **F, int count, void *data, size_t datasiz
if(count > 0) if(count > 0)
{ {
int i;
int len = CMSG_SPACE(sizeof(int) * count); int len = CMSG_SPACE(sizeof(int) * count);
buf = alloca(len); char buf[len];
msg.msg_control = buf; msg.msg_control = buf;
msg.msg_controllen = len; msg.msg_controllen = len;
@ -2254,14 +2251,14 @@ rb_send_fd_buf(rb_fde_t *xF, rb_fde_t **F, int count, void *data, size_t datasiz
cmsg->cmsg_type = SCM_RIGHTS; cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int) * count); cmsg->cmsg_len = CMSG_LEN(sizeof(int) * count);
for(i = 0; i < count; i++) for(unsigned int i = 0; i < count; i++)
{ {
((int *)CMSG_DATA(cmsg))[i] = rb_get_fd(F[i]); ((int *)CMSG_DATA(cmsg))[i] = rb_get_fd(F[i]);
} }
msg.msg_controllen = cmsg->cmsg_len; msg.msg_controllen = cmsg->cmsg_len;
return sendmsg(rb_get_fd(xF), &msg, MSG_NOSIGNAL);
} }
n = sendmsg(rb_get_fd(xF), &msg, MSG_NOSIGNAL); return sendmsg(rb_get_fd(xF), &msg, MSG_NOSIGNAL);
return n;
} }
#else #else
#ifndef _WIN32 #ifndef _WIN32