Limit the maximum length of a text line

To prevent sarg from filling up the memory and waking up the OOM killer
while reading an invalid or corrupted log file, the longest line sarg
will accept before aborting is 10MB long. The limit is arbitrary.

diff --git a/longline.c b/longline.c
index c8feaef3995cfa39dde9ddf5f4052576a781f5ab..1261ea93a2f9796789850199c58d6b6082465e4c 100644 (file)
--- a/longline.c
+++ b/longline.c
@@ -27,7 +27,31 @@
 #include "include/conf.h"
 #include "include/defs.h"
 
+//! The size, in bytes, to allocate from the start.
 #define INITIAL_LINE_BUFFER_SIZE 32768
+/*!
+The amount by which the line buffer size is increased when it turns out to be too small to accomodate
+the line to read.
+*/
+#define LINE_BUFFER_SIZE_INCREMENT 8192
+/*!
+Maximum size of the line buffer.
+
+A text line read from the file must be smaller than this value or the functions fails
+and aborts the program.
+
+10MB should not be a problem as most of the line is filled with the URL and squid 3
+limits the URL to 4096 bytes (see MAX_URL). Squid has reportedly been tested with
+MAX_URL set up to 32KB so I'm not expecting URL much longer than that.
+
+Other proxies might handle longer URLs but certainly not longer than 10MB.
+
+Now, why put a limit? Sarg version 2.3 originaly had no limits until sarg 2.3.3. At
+that point a user with a defective network mount point reported that sarg was eating
+up 8GB of memory available on the server triggering the OOM killer. So the limit is
+here to prevent sarg from choking on an invalid file.
+*/
+#define MAX_LINE_BUFFER_SIZE (10*1024*1024)
 
 struct longlinestruct
 {
@@ -107,7 +131,11 @@ char *longline_read(FILE *fp_in,longline line)
                        line->start=0;
                }
                if (line->length>=line->size) {
-                       line->size+=8192;
+                       line->size+=LINE_BUFFER_SIZE_INCREMENT;
+                       if (line->size>=MAX_LINE_BUFFER_SIZE) {
+                               debuga(_("A text line is more than %d bytes long denoting a corrupted file\n"),MAX_LINE_BUFFER_SIZE);
+                               exit(EXIT_FAILURE);
+                       }
                        newbuf=realloc(line->buffer,line->size);
                        if (!newbuf) {
                                debuga(_("Not enough memory to read one more line from the file\n"));