Re: [syzbot] [media?] KASAN: slab-use-after-free Read in dvb_device_open

[syzbot <syzbot+1eb177ecc3943b883f0a@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in dvb_device_open

------------[ cut here ]------------
open dvb_frontend_open+0x0/0x1750 drivers/media/dvb-core/dvb_frontend.c:2428
WARNING: CPU: 0 PID: 6885 at drivers/media/dvb-core/dvbdev.c:113 dvb_device_open+0x2f7/0x420 drivers/media/dvb-core/dvbdev.c:113
Modules linked in:
CPU: 0 UID: 0 PID: 6885 Comm: syz.3.32 Not tainted 6.13.0-rc7-syzkaller-gfda5e3f28400-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:dvb_device_open+0x2f7/0x420 drivers/media/dvb-core/dvbdev.c:113
Code: 24 50 49 8d 7c 24 68 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 31 01 00 00 49 8b 74 24 68 48 c7 c7 60 aa 2f 8c e8 4a ea d3 f9 90 <0f> 0b 90 90 48 89 ef e8 9d e8 ff ff e8 48 22 13 fa 89 d8 5b 5d 41
RSP: 0018:ffffc90003357920 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 00000000fffffff0 RCX: ffffffff815a17c9
RDX: ffff88802ffdda00 RSI: ffffffff815a17d6 RDI: 0000000000000001
RBP: ffff888143aec000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88802982f400
R13: ffff88802982f400 R14: ffff88802a198808 R15: ffff8880331aa910
FS:  00007f35dfb9e6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000000 CR3: 00000000329e2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 chrdev_open+0x237/0x6a0 fs/char_dev.c:414
 do_dentry_open+0xf59/0x1ea0 fs/open.c:945
 vfs_open+0x82/0x3f0 fs/open.c:1075
 do_open fs/namei.c:3828 [inline]
 path_openat+0x1e6a/0x2d60 fs/namei.c:3987
 do_filp_open+0x20c/0x470 fs/namei.c:4014
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1402
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_openat fs/open.c:1433 [inline]
 __se_sys_openat fs/open.c:1428 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1428
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f35ded85d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f35dfb9e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f35def75fa0 RCX: 00007f35ded85d29
RDX: 0000000000000001 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 00007f35dee01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f35def75fa0 R15: 00007ffc3f7cc208
 </TASK>


Tested on:

commit:         fda5e3f2 Merge tag 'trace-v6.13-rc7-2' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d2fa18580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f5e182416a4b418f
dashboard link: https://syzkaller.appspot.com/bug?extid=1eb177ecc3943b883f0a
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=15a962b0580000