Event pipe: fixed handling of buf_to_file data.
Input filter might free a buffer if there is no data in it, and in case
of first buffer (used for cache header and request header, aka p->buf_to_file)
this resulted in cache corruption. Buffer memory was reused to read upstream
response before headers were written to disk.
Fix is to avoid moving pointers in ngx_event_pipe_add_free_buf() to a buffer
start if we were asked to free a buffer used by p->buf_to_file.
This fixes occasional cache file corruption, usually resulted
in "cache file ... has md5 collision" alerts.
Reported by Anatoli Marinov.
diff --git a/src/event/ngx_event_pipe.c b/src/event/ngx_event_pipe.c
index c2c7983..476d56e 100644
--- a/src/event/ngx_event_pipe.c
+++ b/src/event/ngx_event_pipe.c
@@ -946,8 +946,15 @@
return NGX_ERROR;
}
- b->pos = b->start;
- b->last = b->start;
+ if (p->buf_to_file && b->start == p->buf_to_file->start) {
+ b->pos = p->buf_to_file->last;
+ b->last = p->buf_to_file->last;
+
+ } else {
+ b->pos = b->start;
+ b->last = b->start;
+ }
+
b->shadow = NULL;
cl->buf = b;
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 6c34f39..75ef64e 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2287,6 +2287,7 @@
return;
}
+ p->buf_to_file->start = u->buffer.start;
p->buf_to_file->pos = u->buffer.start;
p->buf_to_file->last = u->buffer.pos;
p->buf_to_file->temporary = 1;
