Merge tag 'execve-v6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - fix up /proc/pid/comm in the execveat(AT_EMPTY_PATH) case (Tycho
   Andersen, Kees Cook)

 - binfmt_misc: Fix comment typos (Christophe JAILLET)

 - move empty argv[0] warning closer to actual logic (Nir Lichtman)

 - remove legacy custom binfmt modules autoloading (Nir Lichtman)

 - Make sure set_task_comm() always NUL-terminates

 - binfmt_flat: Fix integer overflow bug on 32 bit systems (Dan
   Carpenter)

 - coredump: Do not lock when copying "comm"

 - MAINTAINERS: add auxvec.h and set myself as maintainer

* tag 'execve-v6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt_flat: Fix integer overflow bug on 32 bit systems
  selftests/exec: add a test for execveat()'s comm
  exec: fix up /proc/pid/comm in the execveat(AT_EMPTY_PATH) case
  exec: Make sure task->comm is always NUL-terminated
  exec: remove legacy custom binfmt modules autoloading
  exec: move warning of null argv to be next to the relevant code
  fs: binfmt: Fix a typo
  MAINTAINERS: exec: Mark Kees as maintainer
  MAINTAINERS: exec: Add auxvec.h UAPI
  coredump: Do not lock during 'comm' reporting

1 files changed, 72 insertions, 3 deletions

diff --git a/tools/testing/selftests/exec/execveat.c b/tools/testing/selftests/exec/execveat.c
index 071e03532cba..8fb7395fd35b 100644
--- a/tools/testing/selftests/exec/execveat.c
+++ b/tools/testing/selftests/exec/execveat.c
@@ -23,9 +23,11 @@
 
 #include "../kselftest.h"
 
-#define TESTS_EXPECTED 51
+#define TESTS_EXPECTED 54
 #define TEST_NAME_LEN (PATH_MAX * 4)
 
+#define CHECK_COMM "CHECK_COMM"
+
 static char longpath[2 * PATH_MAX] = "";
 static char *envp[] = { "IN_TEST=yes", NULL, NULL };
 static char *argv[] = { "execveat", "99", NULL };
@@ -237,6 +239,29 @@ static int check_execveat_pathmax(int root_dfd, const char *src, int is_script)
 	return fail;
 }
 
+static int check_execveat_comm(int fd, char *argv0, char *expected)
+{
+	char buf[128], *old_env, *old_argv0;
+	int ret;
+
+	snprintf(buf, sizeof(buf), CHECK_COMM "=%s", expected);
+
+	old_env = envp[1];
+	envp[1] = buf;
+
+	old_argv0 = argv[0];
+	argv[0] = argv0;
+
+	ksft_print_msg("Check execveat(AT_EMPTY_PATH)'s comm is %s\n",
+		       expected);
+	ret = check_execveat_invoked_rc(fd, "", AT_EMPTY_PATH, 0, 0);
+
+	envp[1] = old_env;
+	argv[0] = old_argv0;
+
+	return ret;
+}
+
 static int run_tests(void)
 {
 	int fail = 0;
@@ -389,6 +414,14 @@ static int run_tests(void)
 
 	fail += check_execveat_pathmax(root_dfd, "execveat", 0);
 	fail += check_execveat_pathmax(root_dfd, "script", 1);
+
+	/* /proc/pid/comm gives filename by default */
+	fail += check_execveat_comm(fd, "sentinel", "execveat");
+	/* /proc/pid/comm gives argv[0] when invoked via link */
+	fail += check_execveat_comm(fd_symlink, "sentinel", "execveat");
+	/* /proc/pid/comm gives filename if NULL is passed */
+	fail += check_execveat_comm(fd, NULL, "execveat");
+
 	return fail;
 }
 
@@ -415,9 +448,13 @@ int main(int argc, char **argv)
 	int ii;
 	int rc;
 	const char *verbose = getenv("VERBOSE");
+	const char *check_comm = getenv(CHECK_COMM);
 
-	if (argc >= 2) {
-		/* If we are invoked with an argument, don't run tests. */
+	if (argc >= 2 || check_comm) {
+		/*
+		 * If we are invoked with an argument, or no arguments but a
+		 * command to check, don't run tests.
+		 */
 		const char *in_test = getenv("IN_TEST");
 
 		if (verbose) {
@@ -426,6 +463,38 @@ int main(int argc, char **argv)
 				ksft_print_msg("\t[%d]='%s\n'", ii, argv[ii]);
 		}
 
+		/* If the tests wanted us to check the command, do so. */
+		if (check_comm) {
+			/* TASK_COMM_LEN == 16 */
+			char buf[32];
+			int fd, ret;
+
+			fd = open("/proc/self/comm", O_RDONLY);
+			if (fd < 0) {
+				ksft_perror("open() comm failed");
+				exit(1);
+			}
+
+			ret = read(fd, buf, sizeof(buf));
+			if (ret < 0) {
+				ksft_perror("read() comm failed");
+				close(fd);
+				exit(1);
+			}
+			close(fd);
+
+			// trim off the \n
+			buf[ret-1] = 0;
+
+			if (strcmp(buf, check_comm)) {
+				ksft_print_msg("bad comm, got: %s expected: %s\n",
+					       buf, check_comm);
+				exit(1);
+			}
+
+			exit(0);
+		}
+
 		/* Check expected environment transferred. */
 		if (!in_test || strcmp(in_test, "yes") != 0) {
 			ksft_print_msg("no IN_TEST=yes in env\n");