linux-kernel - RE: [syzbot] [fs?] [mm?] INFO: task hung in remove_inode

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Message-ID: <IA0PR11MB71850525CBC7D541CAB45DF1F8DB2@IA0PR11MB7185.namprd11.prod.outlook.com>
Date: Tue, 9 Jul 2024 21:36:00 +0000
From: "Kasireddy, Vivek" <vivek.kasireddy@...el.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: syzbot <syzbot+f1d7fb4f94764243d23e@...kaller.appspotmail.com>,
	"airlied@...hat.com" <airlied@...hat.com>, "kraxel@...hat.com"
	<kraxel@...hat.com>, "linux-fsdevel@...r.kernel.org"
	<linux-fsdevel@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>,
	"muchun.song@...ux.dev" <muchun.song@...ux.dev>,
	"syzkaller-bugs@...glegroups.com" <syzkaller-bugs@...glegroups.com>
Subject: RE: [syzbot] [fs?] [mm?] INFO: task hung in remove_inode_hugepages

Hi Andrew,

> 
> Hello,
> 
> syzbot has tested the proposed patch and the reproducer did not trigger any
> issue:
> 
> Reported-and-tested-by:
> syzbot+f1d7fb4f94764243d23e@...kaller.appspotmail.com
> 
> Tested on:
> 
> commit:         581a87b1 fixup! mm/gup: introduce memfd_pin_folios() f..
> git tree:       https://gitlab.freedesktop.org/Vivek/drm-tip.git
> syzbot_fix_remove_inode

How do you prefer to take the following short fix for this issue?

commit 581a87b19b3739da8c10750b499c55062ea54bf4
Author: Vivek Kasireddy <vivek.kasireddy@...el.com>
Date:   Mon Jul 8 23:04:48 2024 -0700

    fixup! mm/gup: introduce memfd_pin_folios() for pinning memfd folios
    
    Return -EINVAL if the end offset is greater than the size of memfd.
    
    Signed-off-by: Vivek Kasireddy <vivek.kasireddy@...el.com>

diff --git a/mm/gup.c b/mm/gup.c
index 43f6d2f689d2..54d0dc3831fb 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3630,6 +3630,9 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end,
        if (!shmem_file(memfd) && !is_file_hugepages(memfd))
                return -EINVAL;
 
+       if (end >= i_size_read(file_inode(memfd)))
+               return -EINVAL;
+
        if (is_file_hugepages(memfd)) {
                h = hstate_file(memfd);

Thanks,
Vivek

> console output: https://syzkaller.appspot.com/x/log.txt?x=145a8535980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=409b5fcdf33b7555
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=f1d7fb4f94764243d23e
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian)
> 2.40
> 
> Note: no patches were applied.
> Note: testing is done by a robot and is best-effort only.