9pfs: check the size of transport buffer before marshaling
v9fs_do_readdir_with_stat() should check for a maximum buffer size
before an attempt to marshal gathered data. Otherwise, buffers assumed
as misconfigured and the transport would be broken.
The patch brings v9fs_do_readdir_with_stat() in conformity with
v9fs_do_readdir() behavior.
Signed-off-by: Jan Dakinevich <jan.dakinevich@gmail.com>
[groug, regression caused my commit 8d37de41ca # 2.10]
Signed-off-by: Greg Kurz <groug@kaod.org>
			
			
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								hw/9pfs/9p.c
								
								
								
								
							
							
						
						
									
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								hw/9pfs/9p.c
								
								
								
								
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					@ -1748,18 +1748,27 @@ static int coroutine_fn v9fs_do_readdir_with_stat(V9fsPDU *pdu,
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        if (err < 0) {
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					        if (err < 0) {
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            break;
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					            break;
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        }
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					        }
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        /* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */
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					        if ((count + v9stat.size + 2) > max_count) {
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        len = pdu_marshal(pdu, 11 + count, "S", &v9stat);
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					            v9fs_readdir_unlock(&fidp->fs.dir);
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        v9fs_readdir_unlock(&fidp->fs.dir);
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        if ((len != (v9stat.size + 2)) || ((count + len) > max_count)) {
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            /* Ran out of buffer. Set dir back to old position and return */
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					            /* Ran out of buffer. Set dir back to old position and return */
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            v9fs_co_seekdir(pdu, fidp, saved_dir_pos);
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					            v9fs_co_seekdir(pdu, fidp, saved_dir_pos);
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            v9fs_stat_free(&v9stat);
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					            v9fs_stat_free(&v9stat);
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            v9fs_path_free(&path);
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					            v9fs_path_free(&path);
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            return count;
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					            return count;
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        }
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					        }
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					        /* 11 = 7 + 4 (7 = start offset, 4 = space for storing count) */
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					        len = pdu_marshal(pdu, 11 + count, "S", &v9stat);
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					        v9fs_readdir_unlock(&fidp->fs.dir);
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					        if (len < 0) {
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					            v9fs_co_seekdir(pdu, fidp, saved_dir_pos);
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					            v9fs_stat_free(&v9stat);
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					            v9fs_path_free(&path);
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					            return len;
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					        }
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        count += len;
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					        count += len;
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        v9fs_stat_free(&v9stat);
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					        v9fs_stat_free(&v9stat);
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        v9fs_path_free(&path);
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					        v9fs_path_free(&path);
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