src/basic/process-util.c

@@ -124,10 +124,14 @@ int get_process_comm(pid_t pid, char **ret) {
 }
 
 int get_process_cmdline(pid_t pid, size_t max_columns, ProcessCmdlineFlags flags, char **line) {
+        _cleanup_fclose_ FILE *f = NULL;
         _cleanup_free_ char *t = NULL, *ans = NULL;
         const char *p;
-        size_t k;
         int r;
+        size_t k;
+
+        /* This is supposed to be a safety guard against runaway command lines. */
+        size_t max_length = sc_arg_max();
 
         assert(line);
         assert(pid >= 0);
@@ -143,18 +147,36 @@ int get_process_cmdline(pid_t pid, size_t max_columns, ProcessCmdlineFlags flags
          * comm_fallback is false). Returns 0 and sets *line otherwise. */
 
         p = procfs_file_alloca(pid, "cmdline");
-        r = read_full_virtual_file(p, &t, &k);
+        r = fopen_unlocked(p, "re", &f);
         if (r == -ENOENT)
                 return -ESRCH;
         if (r < 0)
                 return r;
 
+        /* We assume that each four-byte character uses one or two columns. If we ever check for combining
+         * characters, this assumption will need to be adjusted. */
+        if ((size_t) 4 * max_columns + 1 < max_columns)
+                max_length = MIN(max_length, (size_t) 4 * max_columns + 1);
+
+        t = new(char, max_length);
+        if (!t)
+                return -ENOMEM;
+
+        k = fread(t, 1, max_length, f);
         if (k > 0) {
                 /* Arguments are separated by NULs. Let's replace those with spaces. */
                 for (size_t i = 0; i < k - 1; i++)
                         if (t[i] == '\0')
                                 t[i] = ' ';
+
+                t[k] = '\0'; /* Normally, t[k] is already NUL, so this is just a guard in case of short read */
         } else {
+                /* We only treat getting nothing as an error. We *could* also get an error after reading some
+                 * data, but we ignore that case, as such an error is rather unlikely and we prefer to get
+                 * some data rather than none. */
+                if (ferror(f))
+                        return -errno;
+
                 if (!(flags & PROCESS_CMDLINE_COMM_FALLBACK))
                         return -ENOENT;
 
@@ -165,7 +187,7 @@ int get_process_cmdline(pid_t pid, size_t max_columns, ProcessCmdlineFlags flags
                 if (r < 0)
                         return r;
 
-                free(t);
+                mfree(t);
                 t = strjoin("[", t2, "]");
                 if (!t)
                         return -ENOMEM;

src/core/transaction.c

@@ -405,7 +405,7 @@ static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsi
                                    j->unit->id,
                                    unit_id == array ? "ordering cycle" : "dependency",
                                    *unit_id, *job_type,
-                                   "%s", unit_ids);
+                                   unit_ids);
 
                 if (delete) {
                         const char *status;
@@ -414,7 +414,7 @@ static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsi
                                    "MESSAGE=%s: Job %s/%s deleted to break ordering cycle starting with %s/%s",
                                    j->unit->id, delete->unit->id, job_type_to_string(delete->type),
                                    j->unit->id, job_type_to_string(j->type),
-                                   "%s", unit_ids);
+                                   unit_ids);
 
                         if (log_get_show_color())
                                 status = ANSI_HIGHLIGHT_RED " SKIP " ANSI_NORMAL;
@@ -432,7 +432,7 @@ static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsi
                 log_struct(LOG_ERR,
                            "MESSAGE=%s: Unable to break cycle starting with %s/%s",
                            j->unit->id, j->unit->id, job_type_to_string(j->type),
-                           "%s", unit_ids);
+                           unit_ids);
 
                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
                                          "Transaction order is cyclic. See system logs for details.");

src/test/test-process-util.c

@@ -236,11 +236,6 @@ static void test_get_process_cmdline_harder(void) {
                 return;
         }
 
-        /* Set RLIMIT_STACK to infinity to test we don't try to allocate unncessarily large values to read
-         * the cmdline. */
-        if (setrlimit(RLIMIT_STACK, &RLIMIT_MAKE_CONST(RLIM_INFINITY)) < 0)
-                log_warning("Testing without RLIMIT_STACK=infinity");
-
         assert_se(unlink(path) >= 0);
 
         assert_se(prctl(PR_SET_NAME, "testa") >= 0);