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Date:   Thu, 14 Apr 2022 11:47:21 -0700
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Subject: [syzbot] UBSAN: array-index-out-of-bounds in pvr2_i2c_core_init
From:   syzbot <syzbot+1a247e36149ffd709a9b@syzkaller.appspotmail.com>
To:     isely@pobox.com, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, mchehab@kernel.org,
        syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    4ea3c6425269 Merge tag 'powerpc-5.18-2' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148cb824f00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=307baecfd5e87ced
dashboard link: https://syzkaller.appspot.com/bug?extid=1a247e36149ffd709a9b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17279a70f00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=121dc124f00000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=142753df700000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=162753df700000
console output: https://syzkaller.appspot.com/x/log.txt?x=122753df700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1a247e36149ffd709a9b@syzkaller.appspotmail.com

pvrusb2: You need to resolve the failing condition before this driver can function.  There should be some earlier messages giving more information about the problem.
pvrusb2: Invalid write control endpoint
================================================================================
UBSAN: array-index-out-of-bounds in drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c:602:13
index -1 is out of range for type 'int [20]'
CPU: 0 PID: 1959 Comm: pvrusb2-context Not tainted 5.18.0-rc1-syzkaller-00401-g4ea3c6425269 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:283
 pvr2_i2c_core_init+0xc7d/0xd30 drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c:602
 pvr2_hdw_setup_low drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2134 [inline]
 pvr2_hdw_setup drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2261 [inline]
 pvr2_hdw_initialize+0x787/0x37d0 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2338
 pvr2_context_check drivers/media/usb/pvrusb2/pvrusb2-context.c:109 [inline]
 pvr2_context_thread_func+0x250/0x850 drivers/media/usb/pvrusb2/pvrusb2-context.c:158
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
================================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 1959 Comm: pvrusb2-context Not tainted 5.18.0-rc1-syzkaller-00401-g4ea3c6425269 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 panic+0x2d7/0x636 kernel/panic.c:250
 ubsan_epilogue+0x4a/0x50 lib/ubsan.c:158
 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:283
 pvr2_i2c_core_init+0xc7d/0xd30 drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c:602
 pvr2_hdw_setup_low drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2134 [inline]
 pvr2_hdw_setup drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2261 [inline]
 pvr2_hdw_initialize+0x787/0x37d0 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2338
 pvr2_context_check drivers/media/usb/pvrusb2/pvrusb2-context.c:109 [inline]
 pvr2_context_thread_func+0x250/0x850 drivers/media/usb/pvrusb2/pvrusb2-context.c:158
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This report is generated by a bot. It may contain errors.
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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
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches