output_cmd_background: fix no file + valid mode

If output_cmd_background is given a valid mode as the first argument,
then there is no file given and an error should be returned.

join_args should not be called with an argc of zero since it sets the
last character to the null terminator. With an argc of zero, the length
is zero causing a heap buffer overflow when setting the byte before the
start of argv to '\0'. This probably will not ever generate a segfault,
but may cause data corruption to whatever is directly before it in
memory. To make other such cases easier to detect, this also adds a
sway_assert in join_args when argc is zero.
This commit is contained in:
Brian Ashworth 2019-02-05 14:13:27 -05:00
parent 09c2a46b3d
commit 89afb761ba
2 changed files with 6 additions and 0 deletions

View file

@ -258,6 +258,9 @@ int unescape_string(char *string) {
}
char *join_args(char **argv, int argc) {
if (!sway_assert(argc > 0, "argc should be positive")) {
return NULL;
}
int len = 0, i;
for (i = 0; i < argc; ++i) {
len += strlen(argv[i]) + 1;

View file

@ -61,6 +61,9 @@ struct cmd_results *output_cmd_background(int argc, char **argv) {
return cmd_results_new(CMD_INVALID,
"Missing background scaling mode.");
}
if (j == 0) {
return cmd_results_new(CMD_INVALID, "Missing background file");
}
wordexp_t p = {0};
char *src = join_args(argv, j);