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BUG: KASAN: stack-out-of-bounds in _copy_to_iter+0x493/0x1420
Read of size 4094 at addr ffff888044c878fa by task syz-executor.5/4171

CPU: 0 PID: 4171 Comm: syz-executor.5 Not tainted 5.19.0-rc6-next-20220715 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x8b/0xb3
 print_report.cold+0x5e/0x5e5
 kasan_report+0xb1/0x1c0
 kasan_check_range+0x35/0x1c0
 memcpy+0x20/0x60
 _copy_to_iter+0x493/0x1420
 get_random_bytes_user+0x345/0x3b0
 random_read_iter+0x44/0x60
 generic_file_splice_read+0x187/0x4d0
 do_splice_to+0x1bc/0x240
 splice_direct_to_actor+0x2ac/0x8c0
 do_splice_direct+0x1b8/0x290
 do_sendfile+0xb1d/0x1280
 __x64_sys_sendfile64+0x149/0x210
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f8676492b19
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f86739e7188 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f86765a6020 RCX: 00007f8676492b19
RDX: 0000000020000040 RSI: 0000000000000007 RDI: 0000000000000006
RBP: 00007f86764ecf6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe9c1c1a3f R14: 00007f86739e7300 R15: 0000000000022000
 </TASK>

The buggy address belongs to stack of task syz-executor.5/4171
 and is located at offset 50 in frame:
 get_random_bytes_user+0x0/0x3b0

This frame has 2 objects:
 [32, 96) 'chacha_state'
 [128, 192) 'block'

The buggy address belongs to the physical page:
page:00000000166a8f40 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x44c87
flags: 0x100000000000000(node=0|zone=1)
raw: 0100000000000000 0000000000000000 ffffea00011321c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888044c87800: 00 00 00 00 00 f3 f3 f3 f3 f3 00 00 00 00 00 00
 ffff888044c87880: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00
>ffff888044c87900: 00 00 00 00 00 f2 f2 f2 f2 00 00 00 00 00 00 00
                                  ^
 ffff888044c87980: 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00
 ffff888044c87a00: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00
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