[syzbot] [squashfs?] VFS: Close: file count is zero (use-after-free)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0e1980c40b6e Add linux-next specific files for 20240531
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13ac4616980000
kernel config: https://syzkaller.appspot.com/x/.config?x=d9c3ca4e54577b88
dashboard link: https://syzkaller.appspot.com/bug?extid=b2cfdac9ae5278d4b621
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17f01564980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14484aba980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/44fb1d8b5978/disk-0e1980c4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a66ce5caf0b2/vmlinux-0e1980c4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8992fc8fe046/bzImage-0e1980c4.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8530480d64fb/mount_0.gz

The issue was bisected to:

commit 344a1d8575b05298d0702a9f9231e57db86a855e
Author: Vivek Kasireddy <vivek.k...@intel.com>
Date: Thu Apr 11 06:59:42 2024 +0000

udmabuf: convert udmabuf driver to use folios

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=153a7026980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=173a7026980000
console output: https://syzkaller.appspot.com/x/log.txt?x=133a7026980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2cfda...@syzkaller.appspotmail.com
Fixes: 344a1d8575b0 ("udmabuf: convert udmabuf driver to use folios")

VFS: Close: file count is 0 (f_op=shmem_file_operations)
------------[ cut here ]------------
kernel BUG at fs/open.c:1514!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 PID: 5089 Comm: syz-executor317 Not tainted 6.10.0-rc1-next-20240531-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:filp_flush+0x152/0x160 fs/open.c:1512
Code: e9 80 e1 07 80 c1 03 38 c1 7c a6 48 89 ef e8 c5 03 f0 ff eb 9c e8 6e 16 8a ff 48 c7 c7 20 59 d8 8b 48 89 ee e8 6f 84 7d 09 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900033bfc80 EFLAGS: 00010246
RAX: 0000000000000038 RBX: 0000000000000000 RCX: fe0d96255f7cdc00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffffff8bd42dc0 R08: ffffffff8176b129 R09: 1ffff92000677f2c
R10: dffffc0000000000 R11: fffff52000677f2d R12: ffff8880784d9680
R13: dffffc0000000000 R14: ffff88807aa761c0 R15: 0000000000000009
FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000003f3be538 CR3: 000000007f062000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
filp_close+0x1e/0x40 fs/open.c:1532
close_files fs/file.c:437 [inline]
put_files_struct+0x1b6/0x360 fs/file.c:452
do_exit+0xa08/0x28e0 kernel/exit.c:869
do_group_exit+0x207/0x2c0 kernel/exit.c:1023
__do_sys_exit_group kernel/exit.c:1034 [inline]
__se_sys_exit_group kernel/exit.c:1032 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032
x64_sys_call+0x26a8/0x26b0 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc324e0fd09
Code: Unable to access opcode bytes at 0x7fc324e0fcdf.
RSP: 002b:00007fffe9a711b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc324e0fd09
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fc324e8b2d0 R08: ffffffffffffffb8 R09: 0000555580c204c0
R10: 0000555580c204c0 R11: 0000000000000246 R12: 00007fc324e8b2d0
R13: 0000000000000000 R14: 00007fc324e8c040 R15: 00007fc324dddf00
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:filp_flush+0x152/0x160 fs/open.c:1512
Code: e9 80 e1 07 80 c1 03 38 c1 7c a6 48 89 ef e8 c5 03 f0 ff eb 9c e8 6e 16 8a ff 48 c7 c7 20 59 d8 8b 48 89 ee e8 6f 84 7d 09 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900033bfc80 EFLAGS: 00010246
RAX: 0000000000000038 RBX: 0000000000000000 RCX: fe0d96255f7cdc00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffffff8bd42dc0 R08: ffffffff8176b129 R09: 1ffff92000677f2c
R10: dffffc0000000000 R11: fffff52000677f2d R12: ffff8880784d9680
R13: dffffc0000000000 R14: ffff88807aa761c0 R15: 0000000000000009
FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000003f3be538 CR3: 000000007f062000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

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=d9c3ca4e54577b88
dashboard link: https://syzkaller.appspot.com/bug?extid=b2cfdac9ae5278d4b621
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=10a6e206980000

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: Re: [syzbot] [squashfs?] VFS: Close: file count is zero (use-after-free)
Author: night...@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 = NULL;
}

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


syzbot <syzbot+b2cfda...@syzkaller.appspotmail.com> 于2024年6月3日周一
13:49写道：

> 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=d9c3ca4e54577b88
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=b2cfdac9ae5278d4b621
> compiler:

> patch:
> https://syzkaller.appspot.com/x/patch.diff?x=10a6e206980000
>
>

[syzbot]

> please test file uaf in udmabuf_create
>
> #syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

want either no args or 2 args (repo, branch), got 1

[syzbot]

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=d9c3ca4e54577b88
dashboard link: https://syzkaller.appspot.com/bug?extid=b2cfdac9ae5278d4b621
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=1106fe16980000

[syzbot]

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: Re: [syzbot] [squashfs?] VFS: Close: file count is zero (use-after-free)
Author: night...@gmail.com

please test file uaf in udmabuf_create

#syz test

[syzbot]

patch: https://syzkaller.appspot.com/x/patch.diff?x=171aa5f2980000

[Nightu Hu]

please test file uaf in udmabuf_create

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

--- 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 = NULL;
        }

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

[Kasireddy, Vivek]

#syz test: https://gitlab.freedesktop.org/Vivek/drm-tip.git syzbot_fixes

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+b2cfda...@syzkaller.appspotmail.com

Tested on:

commit: c7db1220 fixup! udmabuf: pin the pages using memfd_pin..
git tree: https://gitlab.freedesktop.org/Vivek/drm-tip.git syzbot_fixes
console output: https://syzkaller.appspot.com/x/log.txt?x=11b1bb36980000
kernel config: https://syzkaller.appspot.com/x/.config?x=58a2adb83f90b327

dashboard link: https://syzkaller.appspot.com/bug?extid=b2cfdac9ae5278d4b621
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.