linux-kernel - Re: [syzbot] [fs?] KASAN: null-ptr-deref Write in do_pagemap

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Message-ID: <tencent_2749AC6EC9EEFD0CA1A7D706C792C0467906@qq.com>
Date: Tue,  5 Mar 2024 08:56:47 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+02e64be5307d72e9c309@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [fs?] KASAN: null-ptr-deref Write in do_pagemap_cmd

please test null ptr deref in do_pagemap_cmd

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 3f78ebbb795f..ab28666956d0 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2510,6 +2510,8 @@ static long do_pagemap_cmd(struct file *file, unsigned int cmd,
 
 	switch (cmd) {
 	case PAGEMAP_SCAN:
+		if (!mm)
+			return -EINVAL;
 		return do_pagemap_scan(mm, arg);
 
 	default: