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fw_cfg: fix memory corruption when all fw_cfg slots are used
When all the fw_cfg slots are used, a write is made outside the bounds of the fw_cfg files array as part of the sort algorithm. Fix it by avoiding an unnecessary array element move. Fix also an assert while at it. Signed-off-by: Marcel Apfelbaum <marcel@redhat.com> Message-Id: <20180108215007.46471-1-marcel@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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@ -784,7 +784,7 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
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* index and "i - 1" is the one being copied from, thus the
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* unusual start and end in the for statement.
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*/
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for (i = count + 1; i > index; i--) {
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for (i = count; i > index; i--) {
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s->files->f[i] = s->files->f[i - 1];
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s->files->f[i].select = cpu_to_be16(FW_CFG_FILE_FIRST + i);
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s->entries[0][FW_CFG_FILE_FIRST + i] =
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@ -833,7 +833,6 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
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assert(s->files);
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index = be32_to_cpu(s->files->count);
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assert(index < fw_cfg_file_slots(s));
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for (i = 0; i < index; i++) {
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if (strcmp(filename, s->files->f[i].name) == 0) {
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@ -843,6 +842,9 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
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return ptr;
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}
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}
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assert(index < fw_cfg_file_slots(s));
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/* add new one */
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fw_cfg_add_file_callback(s, filename, NULL, NULL, NULL, data, len, true);
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return NULL;
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