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

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

Hello,

syzbot found the following issue on:

HEAD commit:    ac71fabf1567 gcc-15: work around sequence-point warning
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10b4cc70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7a7c679f880028f0
dashboard link: https://syzkaller.appspot.com/bug?extid=0192952caa411a3be209
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=16fedb98580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10edf4cc580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d368be8878a6/disk-ac71fabf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cc783efdaf4c/vmlinux-ac71fabf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d04c29c82c67/bzImage-ac71fabf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0192952caa411a3be209@syzkaller.appspotmail.com

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: 5832 Comm: syz-executor328 Not tainted 6.15.0-rc2-syzkaller-00493-gac71fabf1567 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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:231 [inline]
 __ubsan_handle_out_of_bounds+0x11c/0x160 lib/ubsan.c:453
 az6007_i2c_xfer+0x549/0xc30 drivers/media/usb/dvb-usb-v2/az6007.c:821
 __i2c_transfer+0x6b3/0x2190 drivers/i2c/i2c-core-base.c:2259
 i2c_transfer drivers/i2c/i2c-core-base.c:2315 [inline]
 i2c_transfer+0x1da/0x380 drivers/i2c/i2c-core-base.c:2291
 i2c_transfer_buffer_flags+0x10c/0x190 drivers/i2c/i2c-core-base.c:2343
 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:845 [inline]
 do_loop_readv_writev fs/read_write.c:833 [inline]
 vfs_readv+0x6bc/0x8a0 fs/read_write.c:1018
 do_preadv+0x1af/0x270 fs/read_write.c:1130
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4d458f3929
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:00007ffe002f51e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007ffe002f5230 RCX: 00007f4d458f3929
RDX: 0000000000000001 RSI: 00002000000025c0 RDI: 0000000000000004
RBP: 0000000000000000 R08: 000000000000007e R09: 00007ffe002f5230
R10: 0000000000000002 R11: 0000000000000246 R12: 00000000000f4240
R13: 00007ffe002f54b8 R14: 00007ffe002f521c R15: 00007ffe002f5220
 </TASK>
---[ end trace ]---


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