[llvm-bugs] [Bug 31458] New: False positive Use-after-free about partclone/srv/btrfs/volumes.c line 170

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=31458

            Bug ID: 31458
           Summary: False positive Use-after-free about
                    partclone/srv/btrfs/volumes.c line 170
           Product: clang
           Version: 3.9
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Static Analyzer
          Assignee: kremenek at apple.com
          Reporter: xiangzhai83 at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Hi clang developers,

After reviewed the code
https://github.com/Thomas-Tsai/partclone/blob/master/src/btrfs/volumes.c#L164

I argue that it is false positive Use-after-free for Clang Static Analyzer
https://pbs.twimg.com/media/C0WBcn6VEAAS1Rp.jpg

because device is reassgin!

    while (!list_empty(&fs_devices->devices)) {
--- reassign ----> device = list_entry(fs_devices->devices.next,
                    struct btrfs_device, dev_list);
        if (device->fd != -1) {
            fsync(device->fd);
            if (posix_fadvise(device->fd, 0, 0, POSIX_FADV_DONTNEED))
                fprintf(stderr, "Warning, could not drop caches\n");
            close(device->fd);
            device->fd = -1;
        }
        device->writeable = 0;
        list_del(&device->dev_list);
        /* free the memory */
        free(device->name);
        free(device->label);
        free(device);
    }

Regards,
Leslie Zhai

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