cb8d2ea8c
Xiaoming Ni
2022-11-15
Subject
loop: fix a race when a free loop device is snatched
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libbb/loop.c+10 -1
| @@ -218,8 +218,17 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse | |
| } | |
| /* failure, undo LOOP_SET_FD */ | |
| ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary | |
| + | } else { |
| + | /* device is not free (rc == 0), or error other than ENXIO */ |
| + | if (rc == 0 /* device is not free? */ |
| + | && !*device /* racing with other mount? */ |
| + | && try != dev /* tried a _kernel-offered_ loopN? */ |
| + | ) { |
| + | free(try); |
| + | close(lfd); |
| + | goto get_free_loopN; |
| + | } |
| } | |
| - | /* else: device is not free (rc == 0) or error other than ENXIO */ |
| close_and_try_next_loopN: | |
| close(lfd); | |
| try_next_loopN: | |