• Dave Wysochanski's avatar
    cachefiles: Fix KASAN slab-out-of-bounds in cachefiles_set_volume_xattr · 7b2f6c30
    Dave Wysochanski authored
    Use the actual length of volume coherency data when setting the
    xattr to avoid the following KASAN report.
    
     BUG: KASAN: slab-out-of-bounds in cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
     Write of size 4 at addr ffff888101e02af4 by task kworker/6:0/1347
    
     CPU: 6 PID: 1347 Comm: kworker/6:0 Kdump: loaded Not tainted 5.18.0-rc1-nfs-fscache-netfs+ #13
     Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-4.fc34 04/01/2014
     Workqueue: events fscache_create_volume_work [fscache]
     Call Trace:
      <TASK>
      dump_stack_lvl+0x45/0x5a
      print_report.cold+0x5e/0x5db
      ? __lock_text_start+0x8/0x8
      ? cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
      kasan_report+0xab/0x120
      ? cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
      kasan_check_range+0xf5/0x1d0
      memcpy+0x39/0x60
      cachefiles_set_volume_xattr+0xa0/0x350 [cachefiles]
      cachefiles_acquire_volume+0x2be/0x500 [cachefiles]
      ? __cachefiles_free_volume+0x90/0x90 [cachefiles]
      fscache_create_volume_work+0x68/0x160 [fscache]
      process_one_work+0x3b7/0x6a0
      worker_thread+0x2c4/0x650
      ? process_one_work+0x6a0/0x6a0
      kthread+0x16c/0x1a0
      ? kthread_complete_and_exit+0x20/0x20
      ret_from_fork+0x22/0x30
      </TASK>
    
     Allocated by task 1347:
      kasan_save_stack+0x1e/0x40
      __kasan_kmalloc+0x81/0xa0
      cachefiles_set_volume_xattr+0x76/0x350 [cachefiles]
      cachefiles_acquire_volume+0x2be/0x500 [cachefiles]
      fscache_create_volume_work+0x68/0x160 [fscache]
      process_one_work+0x3b7/0x6a0
      worker_thread+0x2c4/0x650
      kthread+0x16c/0x1a0
      ret_from_fork+0x22/0x30
    
     The buggy address belongs to the object at ffff888101e02af0
     which belongs to the cache kmalloc-8 of size 8
     The buggy address is located 4 bytes inside of
     8-byte region [ffff888101e02af0, ffff888101e02af8)
    
     The buggy address belongs to the physical page:
     page:00000000a2292d70 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101e02
     flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff)
     raw: 0017ffffc0000200 0000000000000000 dead000000000001 ffff888100042280
     raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000
     page dumped because: kasan: bad access detected
    
     Memory state around the buggy address:
     ffff888101e02980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
     ffff888101e02a00: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00
     >ffff888101e02a80: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 04 fc
                                                                ^
     ffff888101e02b00: fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc
     ffff888101e02b80: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
     ==================================================================
    
    Fixes: 413a4a6b "cachefiles: Fix volume coherency attribute"
    Signed-off-by: default avatarDave Wysochanski <dwysocha@redhat.com>
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    cc: linux-cachefs@redhat.com
    Link: https://lore.kernel.org/r/20220405134649.6579-1-dwysocha@redhat.com/ # v1
    Link: https://lore.kernel.org/r/20220405142810.8208-1-dwysocha@redhat.com/ # Incorrect v2
    7b2f6c30
xattr.c 7.73 KB