Commit 15a849be authored by Laszlo Ersek's avatar Laszlo Ersek Committed by Luiz Capitulino
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OptsVisitor: don't try to flatten overlong integer ranges 



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: default avatarLaszlo Ersek <lersek@redhat.com>
Tested-by: default avatarWanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
parent 581a8a80

include/qapi/opts-visitor.h

+6 −0
Original line number Diff line number Diff line
@@ -16,6 +16,12 @@ 
#include "qapi/visitor.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;



/* Contrarily to qemu-option.c::parse_option_number(), OptsVisitor's "int"

qapi/opts-visitor.c

+5 −2
Original line number Diff line number Diff line
@@ -384,7 +384,9 @@ opts_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp) 
            str = endptr + 1;

            val2 = strtoll(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_limit.s = val2;

                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;

            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_limit.u = val2;

                ov->list_mode = LM_UNSIGNED_INTERVAL;