[syzbot] [net?] general protection fault in ptp_ioctl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4652b8e4f3ff Merge tag '6.7-rc-ksmbd-server-fixes' of git:..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11aa125f680000
kernel config: https://syzkaller.appspot.com/x/.config?x=423e70610024fd6b
dashboard link: https://syzkaller.appspot.com/bug?extid=8a78ecea7ac1a2ea26e5
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16193ef7680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17e035d7680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a9cb6d5a8c4b/disk-4652b8e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/363795681962/vmlinux-4652b8e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/113d96b73fef/bzImage-4652b8e4.xz

The issue was bisected to:

commit c5a445b1e9347b14752b01f1a304bd7a2f260acc
Author: Xabier Marquiegui <rei...@gmail.com>
Date: Wed Oct 11 22:39:56 2023 +0000

ptp: support event queue reader channel masks

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=122491ef680000
final oops: https://syzkaller.appspot.com/x/report.txt?x=112491ef680000
console output: https://syzkaller.appspot.com/x/log.txt?x=162491ef680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8a78ec...@syzkaller.appspotmail.com
Fixes: c5a445b1e934 ("ptp: support event queue reader channel masks")

general protection fault, probably for non-canonical address 0xdffffc000000020b: 0000 [#1] PREEMPT SMP KASAN
KASAN: probably user-memory-access in range [0x0000000000001058-0x000000000000105f]
CPU: 0 PID: 5053 Comm: syz-executor353 Not tainted 6.6.0-syzkaller-10396-g4652b8e4f3ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:ptp_ioctl+0xcb7/0x1d10 drivers/ptp/ptp_chardev.c:476
Code: 81 fe 13 3d 00 00 0f 85 9c 02 00 00 e8 c2 83 23 fa 49 8d bc 24 58 10 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 dc 0e 00 00 49 8b bc 24 58 10 00 00 ba 00 01 00
RSP: 0018:ffffc90003a37ba0 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff88814a78a000 RCX: ffffffff8764f81f
RDX: 000000000000020b RSI: ffffffff8765028e RDI: 0000000000001058
RBP: ffffc90003a37ec0 R08: 0000000000000005 R09: ffffc90003a37c40
R10: 0000000000003d13 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc90003a37c80 R14: 0000000000003d13 R15: ffffffff92ac78e8
FS: 00005555569a9380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000040 CR3: 0000000076e09000 CR4: 0000000000350ef0
Call Trace:
<TASK>
posix_clock_ioctl+0xf8/0x160 kernel/time/posix-clock.c:86
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl fs/ioctl.c:857 [inline]
__x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f710ac4a2a9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffda288c4c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffda288c698 RCX: 00007f710ac4a2a9
RDX: 0000000000000000 RSI: 0000000000003d13 RDI: 0000000000000003
RBP: 00007f710acbd610 R08: 00007ffda288c698 R09: 00007ffda288c698
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffda288c688 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ptp_ioctl+0xcb7/0x1d10 drivers/ptp/ptp_chardev.c:476
Code: 81 fe 13 3d 00 00 0f 85 9c 02 00 00 e8 c2 83 23 fa 49 8d bc 24 58 10 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 dc 0e 00 00 49 8b bc 24 58 10 00 00 ba 00 01 00
RSP: 0018:ffffc90003a37ba0 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff88814a78a000 RCX: ffffffff8764f81f
RDX: 000000000000020b RSI: ffffffff8765028e RDI: 0000000000001058
RBP: ffffc90003a37ec0 R08: 0000000000000005 R09: ffffc90003a37c40
R10: 0000000000003d13 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc90003a37c80 R14: 0000000000003d13 R15: ffffffff92ac78e8
FS: 00005555569a9380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005fdeb8 CR3: 0000000076e09000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
0: 81 fe 13 3d 00 00 cmp $0x3d13,%esi
6: 0f 85 9c 02 00 00 jne 0x2a8
c: e8 c2 83 23 fa call 0xfa2383d3
11: 49 8d bc 24 58 10 00 lea 0x1058(%r12),%rdi
18: 00
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 dc 0e 00 00 jne 0xf10
34: 49 8b bc 24 58 10 00 mov 0x1058(%r12),%rdi
3b: 00
3c: ba .byte 0xba
3d: 00 01 add %al,(%rcx)


---
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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

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#syz test: git://repo/address.git branch-or-commit-hash
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[syzbot]

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

***

Subject: [PATCH] null pointer dereference
Author: yuran....@hotmail.com

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

Signed-off-by: Yuran Pereira <yuran....@hotmail.com>
---
drivers/ptp/ptp_chardev.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 282cd7d24077..5b36c34629a0 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -173,6 +173,8 @@ long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
int enable, err = 0;

tsevq = pccontext->private_clkdata;
+ if (!tsevq)
+ return -EINVAL;

switch (cmd) {

--
2.25.1

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+8a78ec...@syzkaller.appspotmail.com

Tested on:

commit: 77fa2fbe Merge tag 'for_linus' of git://git.kernel.org..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=16ba847b680000
kernel config: https://syzkaller.appspot.com/x/.config?x=1ffa1cec3b40f3ce

dashboard link: https://syzkaller.appspot.com/bug?extid=8a78ecea7ac1a2ea26e5
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=15841787680000

Note: testing is done by a robot and is best-effort only.

[Lizhi Xu]

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4652b8e4f3ff
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 282cd7d24077..27c1ef493617 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -585,7 +585,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
free_event:
kfree(event);
exit:
- if (result < 0)
- ptp_release(pccontext);
return result;
}

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+8a78ec...@syzkaller.appspotmail.com

Tested on:

commit: 4652b8e4 Merge tag '6.7-rc-ksmbd-server-fixes' of git:..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11cea00f680000
kernel config: https://syzkaller.appspot.com/x/.config?x=423e70610024fd6b

dashboard link: https://syzkaller.appspot.com/bug?extid=8a78ecea7ac1a2ea26e5
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1219bb08e80000

[Lizhi Xu]

In the logs recorded in the strace log,
https://syzkaller.appspot.com/text?tag=CrashLog&x=11aa125f680000
...
openat(AT_FDCWD, "/dev/ptp0", O_RDONLY) = 3
read(3, 0x20000080, 90) = -1 EINVAL (Invalid argument)

general protection fault, probably for non-canonical address 0xdffffc000000020b: 0000 [#1] PREEMPT SMP KASAN
KASAN: probably user-memory-access in range [0x0000000000001058-0x000000000000105f]
CPU: 0 PID: 5053 Comm: syz-executor353 Not tainted 6.6.0-syzkaller-10396-g4652b8e4f3ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:ptp_ioctl+0xcb7/0x1d10

Code: 81 fe 13 3d 00 00 0f 85 9c 02 00 00 e8 c2 83 23 fa 49 8d bc 24 58 10 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 dc 0e 00 00 49 8b bc 24 58 10 00 00 ba 00 01 00
RSP: 0018:ffffc90003a37ba0 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff88814a78a000 RCX: ffffffff8764f81f
RDX: 000000000000020b RSI: ffffffff8765028e RDI: 0000000000001058
RBP: ffffc90003a37ec0 R08: 0000000000000005 R09: ffffc90003a37c40
R10: 0000000000003d13 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc90003a37c80 R14: 0000000000003d13 R15: ffffffff92ac78e8
FS: 00005555569a9380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000040 CR3: 0000000076e09000 CR4: 0000000000350ef0
Call Trace:
<TASK>

? show_regs+0x8f/0xa0
? die_addr+0x4f/0xd0
? exc_general_protection+0x154/0x230
? asm_exc_general_protection+0x26/0x30
? ptp_ioctl+0x22f/0x1d10
? ptp_ioctl+0xc9e/0x1d10
? ptp_ioctl+0xcb7/0x1d10
? ptp_release+0x2b0/0x2b0
? lockdep_hardirqs_on_prepare+0x410/0x410
? lock_sync+0x190/0x190
? find_held_lock+0x2d/0x110
? ptp_release+0x2b0/0x2b0
posix_clock_ioctl+0xf8/0x160
...

It can be confirmed that after the execution of "read (3, 0x20000080, 90)",
ptp_release() will be called to release the queue and set
pccontext->private_clkdata = NULL at the same time, this is unreasonable and
incorrect. The queue is not the memory requested in ptp_read() and should not
be released in ptp_read().

Signed-off-by: Lizhi Xu <lizh...@windriver.com>
---
drivers/ptp/ptp_chardev.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 282cd7d24077..27c1ef493617 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -585,7 +585,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
free_event:
kfree(event);
exit:
- if (result < 0)
- ptp_release(pccontext);
return result;
}

--
2.25.1

[Rahul Rameshbabu]

On Mon, 06 Nov, 2023 09:19:26 +0800 Lizhi Xu <lizh...@windriver.com> wrote:

<snip>

>
> It can be confirmed that after the execution of "read (3, 0x20000080, 90)",
> ptp_release() will be called to release the queue and set
> pccontext->private_clkdata = NULL at the same time, this is unreasonable and
> incorrect. The queue is not the memory requested in ptp_read() and should not
> be released in ptp_read().
>
> Signed-off-by: Lizhi Xu <lizh...@windriver.com>
> ---
> drivers/ptp/ptp_chardev.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
> index 282cd7d24077..27c1ef493617 100644
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -585,7 +585,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
> free_event:
> kfree(event);
> exit:
> - if (result < 0)
> - ptp_release(pccontext);
> return result;
> }

There is already an ongoing review for a patch submission that covers this.

https://lore.kernel.org/netdev/tencent_856E1C97CCE9E2...@qq.com/

--
Thanks,

Rahul Rameshbabu