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Date: Sun, 02 Jun 2024 22:51:43 -0700
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Subject: Re: [syzbot] Re: [syzbot] [squashfs?] VFS: Close: file count is zero (use-after-free)
From: syzbot <syzbot+b2cfdac9ae5278d4b621@syzkaller.appspotmail.com>
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Subject: Re: [syzbot] [squashfs?] VFS: Close: file count is zero (use-after=
-free)
Author: nightu.pwn@gmail.com

please test file uaf in udmabuf_create

#syz test
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
 0e1980c40b6e

---
 drivers/dma-buf/udmabuf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index afa8bfd2a2a9..53035c601e92 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -382,6 +382,7 @@ static long udmabuf_create(struct miscdevice *device,

                kfree(folios);
                fput(memfd);
+               memfd =3D NULL;
        }

        flags =3D head->flags & UDMABUF_FLAGS_CLOEXEC ? O_CLOEXEC : 0;
--


syzbot <syzbot+b2cfdac9ae5278d4b621@syzkaller.appspotmail.com> =E4=BA=8E202=
4=E5=B9=B46=E6=9C=883=E6=97=A5=E5=91=A8=E4=B8=80
13:49=E5=86=99=E9=81=93=EF=BC=9A

> Hello,
>
> syzbot tried to test the proposed patch but the build/boot failed:
>
> failed to apply patch:
> checking file drivers/dma-buf/udmabuf.c
> patch: **** unexpected end of file in patch
>
>
>
> Tested on:
>
> commit:         861a3cb5 Add linux-next specific files for 20240603
> git tree:       linux-next
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3Dd9c3ca4e54577=
b88
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=3Db2cfdac9ae5278d4b621
> compiler:
> patch:
> https://syzkaller.appspot.com/x/patch.diff?x=3D10a6e206980000
>
>