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authorDenys Vlasenko <vda.linux@googlemail.com>2018-03-11 11:34:44 +0100
committerDenys Vlasenko <vda.linux@googlemail.com>2018-03-11 11:39:05 +0100
commit3d306bffc5981b083ebb365c51e93c2231ff9b22 (patch)
treec47a63aca8a473ae610ffb5aa2d8b8e9584e06fc
parent39dfb4de38fc5b31ca4472dbf45bcde3bb0d6e77 (diff)
downloadbusybox-3d306bffc5981b083ebb365c51e93c2231ff9b22.tar.gz
udhcpd: clamp down huge auto_times to ~2M seconds, better EINTR poll handling
EINTR _should_ only happen on two signals we trap, and safe_poll _should_ work here just fine, but there were kernel bugs where spurious EINTRs happen (e.g. on ptrace attach). Be safe. function old new delta udhcpd_main 1437 1468 +31 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/udhcp/dhcpd.c25
1 files changed, 20 insertions, 5 deletions
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index db3ab4f00..19f94a2d7 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -853,6 +853,9 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
/* Would rather not do read_config before daemonization -
* otherwise NOMMU machines will parse config twice */
read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
+ /* prevent poll timeout overflow */
+ if (server_config.auto_time > INT_MAX / 1000)
+ server_config.auto_time = INT_MAX / 1000;
/* Make sure fd 0,1,2 are open */
bb_sanitize_stdio();
@@ -914,14 +917,26 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
}
udhcp_sp_fd_set(pfds, server_socket);
- tv = timeout_end - monotonic_sec();
- /* Block here waiting for either signal or packet */
- retval = safe_poll(pfds, 2, server_config.auto_time ? tv * 1000 : -1);
- if (retval <= 0) {
- if (retval == 0) {
+
+ new_tv:
+ tv = -1;
+ if (server_config.auto_time) {
+ tv = timeout_end - monotonic_sec();
+ if (tv <= 0) {
+ write_leases:
write_leases();
goto continue_with_autotime;
}
+ tv *= 1000;
+ }
+
+ /* Block here waiting for either signal or packet */
+ retval = poll(pfds, 2, tv);
+ if (retval <= 0) {
+ if (retval == 0)
+ goto write_leases;
+ if (errno == EINTR)
+ goto new_tv;
/* < 0 and not EINTR: should not happen */
bb_perror_msg_and_die("poll");
}