linux-kernel - Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock

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Message-ID: <CAHQche_ieCFxXP-ricwnVMiwwikO8LojWomH9=5eCJEfTm8wVQ@mail.gmail.com>
Date: Wed, 2 Oct 2024 20:14:41 +0800
From: Shu Han <ebpqwerty472123@...il.com>
To: syzbot <syzbot+a6456f6334aa19425886@...kaller.appspotmail.com>
Cc: akpm@...ux-foundation.org, hughd@...gle.com, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, paul@...l-moore.com, stephen.smalley.work@...il.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] possible deadlock in upgrade_mmap_lock_carefully

It seems to be the same as [1].
New LSM hook position for remap_file_pages + IMA = deadlock.
The new LSM hook position is added for a bypass caused by
no check in remap_file_pages + READ_IMPLIES_EXEC in do_mmap.

I suggest fix it by removing the check and moving READ_IMPLIES_EXEC
out of do_mmap[2].

Link: https://lore.kernel.org/lkml/20240928065620.7abadb2d8552f03d785c77c9@linux-foundation.org/
[1]
Link: https://lore.kernel.org/all/20240928180044.50-1-ebpqwerty472123@gmail.com/
[2]