Re: [syzbot] [media?] BUG: corrupted list in az6007_i2c_xfer

[syzbot <syzbot+0192952caa411a3be209@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: array-index-out-of-bounds in az6007_i2c_xfer

usb read operation failed. (-71)
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in drivers/media/usb/dvb-usb-v2/az6007.c:821:30
index 4096 is out of range for type 'unsigned char [4096]'
CPU: 1 UID: 0 PID: 6553 Comm: syz.1.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:233 [inline]
 __ubsan_handle_out_of_bounds+0x11c/0x160 lib/ubsan.c:455
 az6007_i2c_xfer+0x549/0xc30 drivers/media/usb/dvb-usb-v2/az6007.c:821
 __i2c_transfer+0x6b6/0x2190 drivers/i2c/i2c-core-base.c:2264
 i2c_transfer drivers/i2c/i2c-core-base.c:2320 [inline]
 i2c_transfer+0x1da/0x380 drivers/i2c/i2c-core-base.c:2296
 i2c_transfer_buffer_flags+0x10c/0x190 drivers/i2c/i2c-core-base.c:2348
 i2c_master_recv include/linux/i2c.h:79 [inline]
 i2cdev_read+0x111/0x280 drivers/i2c/i2c-dev.c:155
 do_loop_readv_writev fs/read_write.c:847 [inline]
 do_loop_readv_writev fs/read_write.c:835 [inline]
 vfs_readv+0x5c1/0x8b0 fs/read_write.c:1020
 do_preadv+0x1a6/0x270 fs/read_write.c:1132
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faff858e169
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:00007faff9313038 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007faff87b5fa0 RCX: 00007faff858e169
RDX: 0000000000000001 RSI: 00002000000025c0 RDI: 0000000000000004
RBP: 00007faff8610a68 R08: 000000000000007e R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007faff87b5fa0 R15: 00007ffe8b6c0b08
 </TASK>
---[ end trace ]---


Tested on:

commit:         d1d10cea Merge tag 'perf-tools-fixes-for-v6.17-2025-09..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c5e134580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bce5d4c1cf285a6c
dashboard link: https://syzkaller.appspot.com/bug?extid=0192952caa411a3be209
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.