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OptsVisitor: don't try to flatten overlong integer ranges

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Prevent mistyped command line options from incurring high memory and CPU
usage at startup. 64K elements in a range should be enough for everyone
(TM).

The OPTS_VISITOR_RANGE_MAX macro is public so that unit tests can
construct corner cases with it.

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
Laszlo Ersek 2013-08-20 00:35:38 +02:00 committed by Luiz Capitulino
parent 581a8a8000
commit 15a849be10
2 changed files with 11 additions and 2 deletions
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6
include/qapi/opts-visitor.h
View File

@ -16,6 +16,12 @@
#include "qapi/visitor.h" #include "qapi/visitor.h"
#include "qemu/option.h" #include "qemu/option.h"
/* Inclusive upper bound on the size of any flattened range. This is a safety
* (= anti-annoyance) measure; wrong ranges should not cause long startup
* delays nor exhaust virtual memory.
*/
#define OPTS_VISITOR_RANGE_MAX 65536
typedef struct OptsVisitor OptsVisitor; typedef struct OptsVisitor OptsVisitor;
/* Contrarily to qemu-option.c::parse_option_number(), OptsVisitor's "int" /* Contrarily to qemu-option.c::parse_option_number(), OptsVisitor's "int"

7
qapi/opts-visitor.c
View File

@ -384,7 +384,9 @@ opts_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
str = endptr + 1; str = endptr + 1;
val2 = strtoll(str, &endptr, 0); val2 = strtoll(str, &endptr, 0);
if (errno == 0 && endptr > str && *endptr == '\0' && if (errno == 0 && endptr > str && *endptr == '\0' &&
INT64_MIN <= val2 && val2 <= INT64_MAX && val <= val2) { INT64_MIN <= val2 && val2 <= INT64_MAX && val <= val2 &&
(val > INT64_MAX - OPTS_VISITOR_RANGE_MAX ||
val2 < val + OPTS_VISITOR_RANGE_MAX)) {
ov->range_next.s = val; ov->range_next.s = val;
ov->range_limit.s = val2; ov->range_limit.s = val2;
ov->list_mode = LM_SIGNED_INTERVAL; ov->list_mode = LM_SIGNED_INTERVAL;
@ -435,7 +437,8 @@ opts_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
str = endptr + 1; str = endptr + 1;
if (parse_uint_full(str, &val2, 0) == 0 && if (parse_uint_full(str, &val2, 0) == 0 &&
val2 <= UINT64_MAX && val <= val2) { val2 <= UINT64_MAX && val <= val2 &&
val2 - val < OPTS_VISITOR_RANGE_MAX) {
ov->range_next.u = val; ov->range_next.u = val;
ov->range_limit.u = val2; ov->range_limit.u = val2;
ov->list_mode = LM_UNSIGNED_INTERVAL; ov->list_mode = LM_UNSIGNED_INTERVAL;