Limit the max-recursion scan option to 100

There is presently no limit for the max-recursion scan option.
Selecting a max-recursion limit that is too high will cause confusing
errors. E.g.:

/home/aragusa/install.alz/bin/clamscan -d clamav.hdb . --max-recursion=9999999999

LibClamAV Error: fmap_fd: Attempted to get fd for NULL fmap
/home/aragusa/issue/clamav.hdb: Can't allocate memory ERROR
LibClamAV Error: fmap_fd: Attempted to get fd for NULL fmap
/home/aragusa/issue/test.sh: Can't allocate memory ERROR

This commit prevents setting the max-recursion limit higher than 100.

clamd/server-th.c

@@ -50,6 +50,7 @@
 #include "clamav.h"
 #include "others.h"
 #include "readdb.h"
+#include "default.h"
 
 // common
 #include "output.h"
@@ -981,6 +982,12 @@ int recvloop(int *socketds, unsigned nsockets, struct cl_engine *engine, unsigne
 #endif
 
     if ((opt = optget(opts, "MaxRecursion"))->active) {
+        if ((0 == opt->numarg) || (opt->numarg > CLI_MAX_MAXRECLEVEL)) {
+            logg(LOGG_ERROR, "MaxRecursion set to %zu, but cannot be larger than %u, and cannot be 0.\n",
+                    (size_t) opt->numarg, CLI_MAX_MAXRECLEVEL);
+            cl_engine_free(engine);
+            return 1;
+        }
         if ((ret = cl_engine_set_num(engine, CL_ENGINE_MAX_RECURSION, opt->numarg))) {
             logg(LOGG_ERROR, "cl_engine_set_num(CL_ENGINE_MAX_RECURSION) failed: %s\n", cl_strerror(ret));
             cl_engine_free(engine);

clamscan/manager.c

@@ -56,6 +56,7 @@
 #include "matcher-pcre.h"
 #include "str.h"
 #include "readdb.h"
+#include "default.h"
 
 // common
 #include "optparser.h"
@@ -1388,6 +1389,13 @@ int scanmanager(const struct optstruct *opts)
     }
 
     if ((opt = optget(opts, "max-recursion"))->active) {
+        uint32_t opt_value = opt->numarg;
+        if ((0 == opt_value) || (opt_value > CLI_MAX_MAXRECLEVEL)) {
+            logg(LOGG_ERROR, "max-recursion set to %u, but  cannot be larger than %u, and cannot be 0.\n",
+                    opt_value, CLI_MAX_MAXRECLEVEL);
+            ret = 2;
+            goto done;
+        }
         if ((ret = cl_engine_set_num(engine, CL_ENGINE_MAX_RECURSION, opt->numarg))) {
             logg(LOGG_ERROR, "cli_engine_set_num(CL_ENGINE_MAX_RECURSION) failed: %s\n", cl_strerror(ret));
             ret = 2;

docs/man/clamscan.1.in

@@ -232,7 +232,7 @@ Extract and scan at most #n bytes from each archive. The size the archive plus t
 Extract at most #n files from each scanned file (when this is an archive, a document or another kind of container). This option protects your system against DoS attacks (default: 10000)
 .TP
 \fB\-\-max\-recursion=#n\fR
-Set archive recursion level limit. This option protects your system against DoS attacks (default: 17).
+Set archive recursion level limit. This option protects your system against DoS attacks (default: 17) (maximum: 100).
 .TP
 \fB\-\-max\-dir\-recursion=#n\fR
 Maximum depth directories are scanned at (default: 15).

etc/clamd.conf.sample

@@ -585,6 +585,7 @@ Example
 # deeply the process should be continued.
 # Note: setting this limit too high may result in severe damage to the system.
 # Default: 17
+# Maximum: 100
 #MaxRecursion 10
 
 # Number of files to be scanned within an archive, a document, or any other

libclamav/default.h

@@ -58,6 +58,8 @@
 #define CLI_DEFAULT_PCRE_RECMATCH_LIMIT 2000
 #define CLI_DEFAULT_PCRE_MAX_FILESIZE   (1024 * 1024 * 100)   // 100 MB
 
+/* Maximums */
+#define CLI_MAX_MAXRECLEVEL     100
 // clang-format on
 
 #endif

win32/conf_examples/clamd.conf.sample

@@ -557,6 +557,7 @@ TCPAddr localhost
 # deeply the process should be continued.
 # Note: setting this limit too high may result in severe damage to the system.
 # Default: 17
+# Maximum: 100
 #MaxRecursion 10
 
 # Number of files to be scanned within an archive, a document, or any other