[BUG] general protection fault in orangefs_writepages

[Farhad Alemi]

Hello,

As part of the kernel research at ASU's SEFCOM
lab, we hit the crash below. Crash reports can be found here:

  https://github.com/farhad-alemi/public_bug_reports/tree/main/176-general-protection-fault-in-orangefs-writepages/

  Oops: general protection fault, probably for non-canonical address
0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
  KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
  RIP: 0010:orangefs_writepages_callback fs/orangefs/inode.c:144 [inline]
  RIP: 0010:orangefs_writepages+0x642/0xc60 fs/orangefs/inode.c:205
  Call Trace:
   orangefs_writepages+0x642/0xc60 fs/orangefs/inode.c:205
   do_writepages+0x328/0x550 mm/page-writeback.c:2571
   filemap_write_and_wait_range+0x332/0x3f0 mm/filemap.c:685
   orangefs_flush+0x44/0x60 fs/orangefs/file.c:566
   filp_flush+0xbd/0x190 fs/open.c:1467
   filp_close+0x1d/0x40 fs/open.c:1480
   close_files fs/file.c:494 [inline]
   put_files_struct+0x1b6/0x340 fs/file.c:509
   do_exit+0x6a8/0x2360 kernel/exit.c:971

Our reproducer.c is available upon request.

Happy to test a patch if that would help.

Regards,