[syzbot] UBSAN: array-index-out-of-bounds in __anon_vma_prepare

[syzbot <syzbot+66bddd4a39f264bee945@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ff1176468d36 Linux 5.14-rc3
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10034f0e300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=40eef000d7648480
dashboard link: https://syzkaller.appspot.com/bug?extid=66bddd4a39f264bee945
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+66bddd4a39f264bee945@syzkaller.appspotmail.com

================================================================================
UBSAN: array-index-out-of-bounds in kernel/locking/osq_lock.c:34:9
index 117901062 is out of range for type 'long unsigned int [8]'
CPU: 1 PID: 25857 Comm: kworker/u4:3 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:288
 decode_cpu kernel/locking/osq_lock.c:34 [inline]
 osq_lock+0x5ab/0x600 kernel/locking/osq_lock.c:111
 rwsem_optimistic_spin kernel/locking/rwsem.c:746 [inline]
 rwsem_down_write_slowpath+0x1bb/0x11d0 kernel/locking/rwsem.c:1025
 __down_write_common kernel/locking/rwsem.c:1261 [inline]
 __down_write_common kernel/locking/rwsem.c:1258 [inline]
 __down_write kernel/locking/rwsem.c:1270 [inline]
 down_write+0x137/0x150 kernel/locking/rwsem.c:1407
 anon_vma_lock_write include/linux/rmap.h:116 [inline]
 __anon_vma_prepare+0xbf/0x560 mm/rmap.c:203
 anon_vma_prepare include/linux/rmap.h:149 [inline]
 do_anonymous_page mm/memory.c:3765 [inline]
 handle_pte_fault mm/memory.c:4556 [inline]
 __handle_mm_fault+0x4338/0x5320 mm/memory.c:4693
 handle_mm_fault+0x1c8/0x790 mm/memory.c:4791
 faultin_page mm/gup.c:951 [inline]
 __get_user_pages+0x806/0x1430 mm/gup.c:1173
 __get_user_pages_locked mm/gup.c:1359 [inline]
 __get_user_pages_remote+0x18f/0x840 mm/gup.c:1865
 get_user_pages_remote+0x63/0x90 mm/gup.c:1938
 get_arg_page+0xba/0x200 fs/exec.c:220
 copy_string_kernel+0x1b4/0x520 fs/exec.c:631
 kernel_execve+0x25c/0x460 fs/exec.c:1961
 call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
================================================================================


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