[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 01/38] exec: Fix memory allocation when memory p
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH 01/38] exec: Fix memory allocation when memory path names new file |
Date: |
Tue, 01 Mar 2016 12:58:58 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Paolo Bonzini <address@hidden> writes:
> On 29/02/2016 19:40, Markus Armbruster wrote:
>> - if (!stat(path, &st) && S_ISDIR(st.st_mode)) {
>> + ret = stat(path, &st);
>> + if (!ret && S_ISDIR(st.st_mode)) {
>> + /* path names a directory -> create a temporary file there */
>> /* Make name safe to use with mkstemp by replacing '/' with '_'. */
>> sanitized_name = g_strdup(memory_region_name(block->mr));
>> for (c = sanitized_name; *c != '\0'; c++) {
>> @@ -1282,13 +1271,32 @@ static void *file_ram_alloc(RAMBlock *block,
>> unlink(filename);
>> }
>> g_free(filename);
>> + } else if (!ret) {
>> + /* path names an existing file -> use it */
>> + fd = open(path, O_RDWR);
>> } else {
>> + /* create a new file */
>> fd = open(path, O_RDWR | O_CREAT, 0644);
>> + unlink_on_error = true;
>> }
>
> While at it, let's avoid TOCTTOU conditions:
>
> for (;;) {
> fd = open(path, O_RDWR);
> if (fd != -1) {
> break;
> }
> if (errno == ENOENT) {
> fd = open(path, O_RDWR | O_CREAT | O_EXCL, 0644);
> if (fd != -1) {
> unlink_on_error = true;
> break;
> }
> } else if (errno == EISDIR) {
> ... mkstemp ...
> if (fd != -1) {
> unlink_on_error = true;
> break;
> }
> }
> if (errno != EEXIST && errno != EINTR) {
> goto error;
> }
> }
>
> and use fstatfs in gethugepagesize.
Good point, will do!