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In io_callback() service writes before reads. That way, if both

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SUDO_EV_READ and SUDO_EV_WRITE are set and read() returns 0 (EOF)
we don't close the fd before the write() is performed.

If the write() returns EPIPE, ENXIO, EIO or EBADF, clear SUDO_EV_READ
before we close the fd to avoid calling read() on a closed fd.
This commit is contained in:
Todd C. Miller
2015-07-08 10:12:15 -06:00
parent 445e6f2e9a
commit 61182c87ea
1 changed files with 49 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

97
src/exec_pty.c
View File

@@ -551,54 +551,6 @@ io_callback(int fd, int what, void *v)
int n; int n;
debug_decl(io_callback, SUDO_DEBUG_EXEC); debug_decl(io_callback, SUDO_DEBUG_EXEC);
if (ISSET(what, SUDO_EV_READ)) {
evbase = sudo_ev_get_base(iob->revent);
do {
n = read(fd, iob->buf + iob->len, sizeof(iob->buf) - iob->len);
} while (n == -1 && errno == EINTR);
switch (n) {
case -1:
if (errno == EAGAIN)
break;
/* treat read error as fatal and close the fd */
sudo_debug_printf(SUDO_DEBUG_ERROR,
"error reading fd %d: %s", fd, strerror(errno));
/* FALLTHROUGH */
case 0:
/* got EOF or pty has gone away */
if (n == 0) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"read EOF from fd %d", fd);
}
safe_close(fd);
ev_free_by_fd(evbase, fd);
/* If writer already consumed the buffer, close it too. */
if (iob->wevent != NULL && iob->off == iob->len) {
safe_close(sudo_ev_get_fd(iob->wevent));
ev_free_by_fd(evbase, sudo_ev_get_fd(iob->wevent));
iob->off = iob->len = 0;
}
break;
default:
sudo_debug_printf(SUDO_DEBUG_INFO,
"read %d bytes from fd %d", n, fd);
if (!iob->action(iob->buf + iob->len, n, iob))
terminate_command(cmnd_pid, true);
iob->len += n;
/* Enable writer if not /dev/tty or we are foreground pgrp. */
if (iob->wevent != NULL &&
(foreground || !USERTTY_EVENT(iob->wevent))) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
/* Re-enable reader if buffer is not full. */
if (iob->len != sizeof(iob->buf)) {
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
break;
}
}
if (ISSET(what, SUDO_EV_WRITE)) { if (ISSET(what, SUDO_EV_WRITE)) {
evbase = sudo_ev_get_base(iob->wevent); evbase = sudo_ev_get_base(iob->wevent);
do { do {
@@ -615,6 +567,7 @@ io_callback(int fd, int what, void *v)
"unable to write %d bytes to fd %d", "unable to write %d bytes to fd %d",
iob->len - iob->off, fd); iob->len - iob->off, fd);
if (iob->revent != NULL) { if (iob->revent != NULL) {
CLR(what, SUDO_EV_READ);
safe_close(sudo_ev_get_fd(iob->revent)); safe_close(sudo_ev_get_fd(iob->revent));
ev_free_by_fd(evbase, sudo_ev_get_fd(iob->revent)); ev_free_by_fd(evbase, sudo_ev_get_fd(iob->revent));
} }
@@ -664,6 +617,54 @@ io_callback(int fd, int what, void *v)
} }
} }
} }
if (ISSET(what, SUDO_EV_READ)) {
evbase = sudo_ev_get_base(iob->revent);
do {
n = read(fd, iob->buf + iob->len, sizeof(iob->buf) - iob->len);
} while (n == -1 && errno == EINTR);
switch (n) {
case -1:
if (errno == EAGAIN)
break;
/* treat read error as fatal and close the fd */
sudo_debug_printf(SUDO_DEBUG_ERROR,
"error reading fd %d: %s", fd, strerror(errno));
/* FALLTHROUGH */
case 0:
/* got EOF or pty has gone away */
if (n == 0) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"read EOF from fd %d", fd);
}
safe_close(fd);
ev_free_by_fd(evbase, fd);
/* If writer already consumed the buffer, close it too. */
if (iob->wevent != NULL && iob->off == iob->len) {
safe_close(sudo_ev_get_fd(iob->wevent));
ev_free_by_fd(evbase, sudo_ev_get_fd(iob->wevent));
iob->off = iob->len = 0;
}
break;
default:
sudo_debug_printf(SUDO_DEBUG_INFO,
"read %d bytes from fd %d", n, fd);
if (!iob->action(iob->buf + iob->len, n, iob))
terminate_command(cmnd_pid, true);
iob->len += n;
/* Enable writer if not /dev/tty or we are foreground pgrp. */
if (iob->wevent != NULL &&
(foreground || !USERTTY_EVENT(iob->wevent))) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
/* Re-enable reader if buffer is not full. */
if (iob->len != sizeof(iob->buf)) {
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
break;
}
}
} }
static void static void