Re: [syzbot] [media?] general protection fault in dvb_usbv2_generic_write

From: syzbot
Date: Mon Apr 14 2025 - 10:51:46 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: 8ffd015db85f Linux 6.15-rc2
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11fca0cc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a972ee73c2fcf8ca
dashboard link: https://syzkaller.appspot.com/bug?extid=f9f5333782a854509322
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=12827398580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=161620cc580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2640fd4fd0f2/disk-8ffd015d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1c5931df89bc/vmlinux-8ffd015d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f8fece45017d/bzImage-8ffd015d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f9f5333782a854509322@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
CPU: 1 UID: 0 PID: 5849 Comm: syz-executor279 Not tainted 6.15.0-rc2-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:580 [inline]
RIP: 0010:__mutex_lock+0x15d/0x10c0 kernel/locking/mutex.c:746
Code: c0 80 f6 73 9a 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 07 0e 00 00 83 3d 40 ba 41 0e 00 75 21 49 8d 7e 60 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 17 52 fb f5 4d 39 76 60 0f 85 81 0d 00 00
RSP: 0018:ffffc90004206f80 EFLAGS: 00010202
RAX: 0000000000000019 RBX: ffffc90004207040 RCX: ffffffff9a73f603
RDX: ffff888035f65a00 RSI: ffffffff8e4fde18 RDI: 00000000000000c8
RBP: ffffc90004207118 R08: ffffc90004207087 R09: 0000000000000000
R10: ffffc90004207060 R11: fffff52000840e11 R12: 0000000000000000
R13: ffffc90004207048 R14: 0000000000000068 R15: dffffc0000000000
FS: 0000555594939380(0000) GS:ffff888125093000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f79554c50f0 CR3: 000000007cfd2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
dvb_usbv2_generic_write+0x26/0x50 drivers/media/usb/dvb-usb-v2/dvb_usb_urb.c:77
mxl111sf_ctrl_msg+0x172/0x2e0 drivers/media/usb/dvb-usb-v2/mxl111sf.c:73
mxl111sf_write_reg+0xda/0x1f0 drivers/media/usb/dvb-usb-v2/mxl111sf.c:123
mxl111sf_i2c_start drivers/media/usb/dvb-usb-v2/mxl111sf-i2c.c:130 [inline]
mxl111sf_i2c_sw_xfer_msg drivers/media/usb/dvb-usb-v2/mxl111sf-i2c.c:-1 [inline]
mxl111sf_i2c_xfer+0x923/0x8aa0 drivers/media/usb/dvb-usb-v2/mxl111sf-i2c.c:813
__i2c_transfer+0x859/0x2250 drivers/i2c/i2c-core-base.c:-1
i2c_transfer+0x2c2/0x430 drivers/i2c/i2c-core-base.c:2315
i2c_transfer_buffer_flags+0x182/0x260 drivers/i2c/i2c-core-base.c:2343
i2c_master_recv include/linux/i2c.h:79 [inline]
i2cdev_read+0x10a/0x220 drivers/i2c/i2c-dev.c:155
vfs_read+0x21f/0xb90 fs/read_write.c:568
ksys_read+0x19d/0x2d0 fs/read_write.c:713
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f795544e4e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007ffc002847a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f795544e4e9
RDX: 0000000000000063 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00000000000f4240 R08: 00232d6332692f76 R09: 00000000000000a0
R10: 000000000000000f R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc002849c8 R14: 00007ffc002847d0 R15: 00007ffc002847c0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:580 [inline]
RIP: 0010:__mutex_lock+0x15d/0x10c0 kernel/locking/mutex.c:746
Code: c0 80 f6 73 9a 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 07 0e 00 00 83 3d 40 ba 41 0e 00 75 21 49 8d 7e 60 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 17 52 fb f5 4d 39 76 60 0f 85 81 0d 00 00
RSP: 0018:ffffc90004206f80 EFLAGS: 00010202

RAX: 0000000000000019 RBX: ffffc90004207040 RCX: ffffffff9a73f603
RDX: ffff888035f65a00 RSI: ffffffff8e4fde18 RDI: 00000000000000c8
RBP: ffffc90004207118 R08: ffffc90004207087 R09: 0000000000000000
R10: ffffc90004207060 R11: fffff52000840e11 R12: 0000000000000000
R13: ffffc90004207048 R14: 0000000000000068 R15: dffffc0000000000
FS: 0000555594939380(0000) GS:ffff888125093000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055dccfef9670 CR3: 000000007cfd2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: c0 80 f6 73 9a 48 c1 rolb $0xc1,0x489a73f6(%rax)
7: e8 03 42 0f b6 call 0xb60f420f
c: 04 38 add $0x38,%al
e: 84 c0 test %al,%al
10: 0f 85 07 0e 00 00 jne 0xe1d
16: 83 3d 40 ba 41 0e 00 cmpl $0x0,0xe41ba40(%rip) # 0xe41ba5d
1d: 75 21 jne 0x40
1f: 49 8d 7e 60 lea 0x60(%r14),%rdi
23: 48 89 f8 mov %rdi,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction
2f: 74 05 je 0x36
31: e8 17 52 fb f5 call 0xf5fb524d
36: 4d 39 76 60 cmp %r14,0x60(%r14)
3a: 0f 85 81 0d 00 00 jne 0xdc1


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