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authorDenys Vlasenko <vda.linux@googlemail.com>2013-09-11 12:59:21 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2013-09-11 12:59:21 (GMT)
commitfbe250db76b409a99457b47486a09b57677d5108 (patch)
tree1b222f195c0947502c46d375e35f549eb4cbe9b0
parentb5352078a7eb16c33404a8b079aaa9c2b994546c (diff)
downloadbusybox-fbe250db76b409a99457b47486a09b57677d5108.tar.gz
busybox-fbe250db76b409a99457b47486a09b57677d5108.tar.bz2
httpd: treat errors from stdin correctly.
Fron bug report: If a CGI or proxied connection is rudely aborted (SIG_{KILL,BUS,SEGV}) then httpd will spin madly the poll loop in: networking/httpd.c:1080 cgi_io_loop_and_exit() Upon investigation I found that pfd[0].revents == 0x0018 (POLLHUP|POLLERR), which leads to empty read, but the pfd[0].fd (STDIN_FILENO) is left open, and in the FD list given to poll() which immediately returns to once again inform the loop of (POLLHUP|POLLERR) condition of pfd[0].fd. This continues until pfd[FROM_CGI].revents != 0 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/httpd.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/networking/httpd.c b/networking/httpd.c
index cef9b8b..1433313 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -1105,16 +1105,21 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
/* NB: breaking out of this loop jumps to log_and_exit() */
out_cnt = 0;
while (1) {
- memset(pfd, 0, sizeof(pfd));
+ /* Note: even pfd[0].events == 0 won't prevent
+ * revents == POLLHUP|POLLERR reports from closed stdin.
+ * This works: */
+ pfd[0].fd = -1;
pfd[FROM_CGI].fd = fromCgi_rd;
pfd[FROM_CGI].events = POLLIN;
- if (toCgi_wr) {
- pfd[TO_CGI].fd = toCgi_wr;
- if (hdr_cnt > 0) {
- pfd[TO_CGI].events = POLLOUT;
- } else if (post_len > 0) {
+ pfd[TO_CGI].fd = toCgi_wr;
+ pfd[TO_CGI].events = POLLOUT;
+
+ if (toCgi_wr && hdr_cnt <= 0) {
+ if (post_len > 0) {
+ /* Expect more POST data from network */
+ pfd[0].fd = 0;
pfd[0].events = POLLIN;
} else {
/* post_len <= 0 && hdr_cnt <= 0:
@@ -1127,7 +1132,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
}
/* Now wait on the set of sockets */
- count = safe_poll(pfd, toCgi_wr ? TO_CGI+1 : FROM_CGI+1, -1);
+ count = safe_poll(pfd, hdr_cnt > 0 ? TO_CGI+1 : FROM_CGI+1, -1);
if (count <= 0) {
#if 0
if (safe_waitpid(pid, &status, WNOHANG) <= 0) {
@@ -1144,7 +1149,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
}
if (pfd[TO_CGI].revents) {
- /* hdr_cnt > 0 here due to the way pfd[TO_CGI].events set */
+ /* hdr_cnt > 0 here due to the way poll() called */
/* Have data from peer and can write to CGI */
count = safe_write(toCgi_wr, hdr_ptr, hdr_cnt);
/* Doesn't happen, we dont use nonblocking IO here