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bugfix: avoid access after free

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if src is NULL due to a previous error we cannot use it in the command
result string.

Moreover if `src` points to `p.we_wordv[0]` we cannot use it after
`wordfree(&p)` in the command result string.

Bonus feature: If there was an error accessing the file, the string
rapresentation of the error is now included in the command result
string.
This commit is contained in:
ael-code 2018-06-22 15:41:44 +02:00
parent 202ee51150
commit ad085c1332
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GPG key ID: 3390538CF7E96023
1 changed files with 14 additions and 7 deletions
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21
sway/commands/output/background.c
View file

@ -3,6 +3,7 @@
#include <strings.h> #include <strings.h>
#include <unistd.h> #include <unistd.h>
#include <wordexp.h> #include <wordexp.h>
#include <errno.h>
#include "sway/commands.h" #include "sway/commands.h"
#include "sway/config.h" #include "sway/config.h"
#include "log.h" #include "log.h"
@ -71,21 +72,27 @@ struct cmd_results *output_cmd_background(int argc, char **argv) {
if (conf) { if (conf) {
char *conf_path = dirname(conf); char *conf_path = dirname(conf);
src = malloc(strlen(conf_path) + strlen(src) + 2); src = malloc(strlen(conf_path) + strlen(src) + 2);
if (src) { if (!src) {
sprintf(src, "%s/%s", conf_path, p.we_wordv[0]); free(conf);
} else { wordfree(&p);
wlr_log(L_ERROR, wlr_log(L_ERROR,
"Unable to allocate background source"); "Unable to allocate resource: Not enough memory");
return cmd_results_new(CMD_FAILURE, "output",
"Unable to allocate resources");
} }
sprintf(src, "%s/%s", conf_path, p.we_wordv[0]);
free(conf); free(conf);
} else { } else {
wlr_log(L_ERROR, "Unable to allocate background source"); wlr_log(L_ERROR, "Unable to allocate background source");
} }
} }
if (!src || access(src, F_OK) == -1) {
if (access(src, F_OK) == -1) {
struct cmd_results *cmd_res = cmd_results_new(CMD_FAILURE, "output",
"Unable to access background file '%s': %s", src, strerror(errno));
free(src);
wordfree(&p); wordfree(&p);
return cmd_results_new(CMD_INVALID, "output", return cmd_res;
"Background file unreadable (%s).", src);
} }
output->background = strdup(src); output->background = strdup(src);