Crash when mob cast skill

[mrpond]

rAthena Hash

13bc3e2

Client Date

20131120

Server Mode

Pre-Renewal

Result

this is my temp fix

static int8 skill_castend_id_check(struct block_list *src, struct block_list *target, uint16 skill_id, uint16 skill_lv) {
	std::shared_ptr<s_skill_db> skill = skill_db.find(skill_id);

#ifdef 1
	if (nullptr == skill) // invalid skill id
		return USESKILL_FAIL_MAX;
#endif
	...

Relevant Log Output

See picture above

Expected Result

It should not crash

How to Reproduce

When mob cast character lock-on skill, map will crash
maybe unit.cpp line 2857 cause this.

Official Information

N/A

Modifications that may affect results

#define RENEWAL_CAST

[aleos89]

Do you have something custom calling this? You have skill_lv=3 and skill_id=0 being passed to this function.

Somehow you are either clearing ud->skill_id or not properly accounting for something from skill_castend_id. We could add nullptr checks here but technically you shouldn't be failing to look up skills in these locations. If you are the crash is valid and it's a result of a problem somewhere else.

[mrpond]

nothing, the bug happens after #8302.

I think this is ffe40de#diff-7aa01f32243f325129ff31983fd8166d61e578b8e7855fa7c8684f5c346b5167R2857 the problem

[Lemongrass3110]

You clearly have modifications in your file:

Line 13348 of skill.cpp is:

						case TR_METALIC_FURY: // Don't know the official increase. For now lets do up to 50% increase.

Nevertheless I think you are right.

[Playtester]

@mrpond Any idea which monster skill is causing this?

skill_id gets cleared when a monster does a normal attack, it shouldn't happen while a skill is currently being processed, but above looks like it's some kind of skill that creates a timer and then expects the skill_id to still be set at the end of the timer.

Edit: Actually usually the timer here is usually the end of the casttime. But that would mean the monster must have managed to do a successful normal attack while casting. Hmm.

Is skill.cpp line 13348 in your source code this?

		// Failing
		if (fail || (res = skill_castend_id_check(src, target, ud->skill_id, ud->skill_lv)) >= 0) {
			if (sd && res != USESKILL_FAIL_MAX)
				clif_skill_fail( *sd, ud->skill_id, (enum useskill_fail_cause)res );
			break;
		}

[Playtester]

@Playtester here skill.cpp skill.zip

That file also doesn't contain a skill_castend_id_check call in line 13348.

But I assume it's the section I quoted.

Would still need to know what skill causes this. Can you reproduce it with a certain skill?

Do you allow monsters to attack while casting? Is it when the spell gets cast-cancelled?

[Playtester]

The issue can be reproduced when a player has the "Freecast" ability, but not sure how it happens with monsters. Still should be fixed so that we don't set it to 0 when a skilltimer exists.

I'll propose the following fix:

		// Only reset skill_id here if no skilltimer is currently ongoing
		if (ud->skilltimer == INVALID_TIMER)
			ud->skill_id = 0;

[Playtester]

Can you check if the linked PR fixes the issue for you?

[mrpond]

Can you check if the linked PR fixes the issue for you?

yes, we'll test it on production server (1800 Players) for you.

[mrpond]

@Playtester if you had time, #8310
kindly look into this and make PR. I add some fix about bot/custom client can bypass pin code system.

[Playtester]

I'll notify Lemon about that one.