On Sun, Feb 02, 2025 at 09:54:16AM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 69e858e0b8b2 Merge tag 'uml-for-linus-6.14-rc1' of git://g.. > > ------------[ cut here ]------------ > UBSAN: shift-out-of-bounds in lib/xarray.c:147:16 > shift exponent 192 is too large for 64-bit type 'unsigned long' > CPU: 0 UID: 0 PID: 2666 Comm: kworker/u4:9 Not tainted 6.13.0-syzkaller-09760-g69e858e0b8b2 #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 > Workqueue: loop0 loop_rootcg_workfn > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > ubsan_epilogue lib/ubsan.c:231 [inline] > __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468 > get_offset lib/xarray.c:147 [inline] > xas_descend lib/xarray.c:207 [inline] > xas_load+0x583/0x5c0 lib/xarray.c:246 > filemap_get_entry+0x1f0/0x3b0 mm/filemap.c:1860 This is an xarray issue. I suspect it's a race condition, although it could be somebody doing a misplaced DMA or something. How easy is it to reproduce? (nb: I am on holiday for the next week, so I'm not going to be focused on this, I just don't want other people wasting their time looking for a bug somewhere that it isn't)
