tests: add a fuzzer for process_wtmp_file

Signed-off-by: Evgeny Vereshchagin <evvers@ya.ru>

diff --git a/login-utils/Makemodule.am b/login-utils/Makemodule.am
index 4e455f66b92085fd90ec54e581961cc555107cfc..ffcfcb0e47c46f3231df28576f34b445752d0b76 100644 (file)
--- a/login-utils/Makemodule.am
+++ b/login-utils/Makemodule.am
@@ -11,6 +11,18 @@ install-exec-hook-last:
        cd $(DESTDIR)$(usrbin_execdir) && ln -sf last lastb
 
 INSTALL_EXEC_HOOKS += install-exec-hook-last
+
+if FUZZING_ENGINE
+check_PROGRAMS += test_last_fuzz
+
+# https://google.github.io/oss-fuzz/getting-started/new-project-guide/#Requirements
+nodist_EXTRA_test_last_fuzz_SOURCES = dummy.cxx
+
+test_last_fuzz_SOURCES = login-utils/last.c
+test_last_fuzz_CFLAGS = $(AM_CFLAGS) -DFUZZ_TARGET
+test_last_fuzz_LDADD = $(LDADD) libcommon.la $(LIB_FUZZING_ENGINE)
+endif
+
 endif
 
 if BUILD_SULOGIN

diff --git a/login-utils/last.c b/login-utils/last.c
index 9d71ba4435d93fdba6d013a12df269349e581dda..4a90bad282cdc29f41b2f874f39be53afd3e8731 100644 (file)
--- a/login-utils/last.c
+++ b/login-utils/last.c
@@ -53,6 +53,10 @@
 #include "timeutils.h"
 #include "monotonic.h"
 
+#ifdef FUZZ_TARGET
+#include "fuzz.h"
+#endif
+
 #ifndef SHUTDOWN_TIME
 # define SHUTDOWN_TIME 254
 #endif
@@ -157,6 +161,7 @@ static unsigned int recsdone;       /* Number of records listed */
 static time_t lastdate;                /* Last date we've seen */
 static time_t currentdate;     /* date when we started processing the file */
 
+#ifndef FUZZ_TARGET
 /* --time-format=option parser */
 static int which_time_format(const char *s)
 {
@@ -168,6 +173,7 @@ static int which_time_format(const char *s)
        }
        errx(EXIT_FAILURE, _("unknown time format: %s"), s);
 }
+#endif
 
 /*
  *     Read one utmp entry, return in new format.
@@ -258,6 +264,7 @@ static int uread(FILE *fp, struct utmpx *u,  int *quit, const char *filename)
        return 1;
 }
 
+#ifndef FUZZ_TARGET
 /*
  *     Print a short date.
  */
@@ -286,6 +293,7 @@ static void quit_handler(int sig __attribute__((unused)))
        warnx(_("Interrupted %s"), showdate());
        signal(SIGQUIT, quit_handler);
 }
+#endif
 
 /*
  *     Lookup a host with DNS.
@@ -564,7 +572,7 @@ static int list(const struct last_control *ctl, struct utmpx *p, time_t logout_t
        return 0;
 }
 
-
+#ifndef FUZZ_TARGET
 static void __attribute__((__noreturn__)) usage(const struct last_control *ctl)
 {
        FILE *out = stdout;
@@ -599,6 +607,7 @@ static void __attribute__((__noreturn__)) usage(const struct last_control *ctl)
 
        exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 }
+#endif
 
 static int is_phantom(const struct last_control *ctl, struct utmpx *ut)
 {
@@ -660,17 +669,23 @@ static void process_wtmp_file(const struct last_control *ctl,
        int quit = 0;           /* Flag */
        int down = 0;           /* Down flag */
 
+#ifndef FUZZ_TARGET
        time(&lastdown);
+#else
+       lastdown = 1596001948;
+#endif
        /*
         * Fill in 'lastdate'
         */
        lastdate = currentdate = lastrch = lastdown;
 
+#ifndef FUZZ_TARGET
        /*
         * Install signal handlers
         */
        signal(SIGINT, int_handler);
        signal(SIGQUIT, quit_handler);
+#endif
 
        /*
         * Open the utmp file
@@ -907,6 +922,36 @@ static void process_wtmp_file(const struct last_control *ctl,
        }
 }
 
+#ifdef FUZZ_TARGET
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+       struct last_control ctl = {
+               .showhost = TRUE,
+               .name_len = LAST_LOGIN_LEN,
+               .time_fmt = LAST_TIMEFTM_SHORT,
+               .domain_len = LAST_DOMAIN_LEN,
+               .boot_time = {
+                       .tv_sec = 1595978419,
+                       .tv_usec = 816074
+               }
+       };
+       char name[] = "/tmp/test-last-fuzz.XXXXXX";
+       int fd;
+       ssize_t n;
+
+       fd = mkostemp(name, O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC);
+       assert(fd >= 0);
+
+       n = write(fd, data, size);
+       assert(n == (ssize_t) size);
+
+       process_wtmp_file(&ctl, name);
+
+       close(fd);
+       unlink(name);
+
+       return 0;
+}
+#else
 int main(int argc, char **argv)
 {
        struct last_control ctl = {
@@ -1041,3 +1086,4 @@ int main(int argc, char **argv)
        free(files);
        return EXIT_SUCCESS;
 }
+#endif

diff --git a/tools/oss-fuzz.sh b/tools/oss-fuzz.sh
index 60aeb3b598a7bcceaa6d6b0a97e48c654377ac61..23b10fbd4a1d4245daa5d1e6faeeeb16ff68ec31 100755 (executable)
--- a/tools/oss-fuzz.sh
+++ b/tools/oss-fuzz.sh
@@ -18,7 +18,7 @@ export OUT=${OUT:-$(pwd)/out}
 mkdir -p $OUT
 
 ./autogen.sh
-./configure --disable-all-programs --enable-fuzzing-engine --enable-libmount --enable-libblkid
+./configure --disable-all-programs --enable-last --enable-fuzzing-engine --enable-libmount --enable-libblkid
 make -j$(nproc) V=1 check-programs
 
 find . -maxdepth 1 -type f -executable -name "test_*_fuzz" -exec mv {} $OUT \;