6.15-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
commit 43e7e284fc77b710d899569360ea46fa3374ae22 upstream.
The handling of received data in the smbdirect client code involves using copy_to_iter() to copy data from the smbd_reponse struct's packet trailer to a folioq buffer provided by netfslib that encapsulates a chunk of pagecache.
If, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks then performed in copy_to_iter() oopsing with something like the following:
CIFS: Attempting to mount //172.31.9.1/test CIFS: VFS: RDMA transport established usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)! ------------[ cut here ]------------ kernel BUG at mm/usercopy.c:102! ... RIP: 0010:usercopy_abort+0x6c/0x80 ... Call Trace: <TASK> __check_heap_object+0xe3/0x120 __check_object_size+0x4dc/0x6d0 smbd_recv+0x77f/0xfe0 [cifs] cifs_readv_from_socket+0x276/0x8f0 [cifs] cifs_read_from_socket+0xcd/0x120 [cifs] cifs_demultiplex_thread+0x7e9/0x2d50 [cifs] kthread+0x396/0x830 ret_from_fork+0x2b8/0x3b0 ret_from_fork_asm+0x1a/0x30
The problem is that the smbd_response slab's packet field isn't marked as being permitted for usercopy.
Fix this by passing parameters to kmem_slab_create() to indicate that copy_to_iter() is permitted from the packet region of the smbd_response slab objects, less the header space.
Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Reported-by: Stefan Metzmacher metze@samba.org Link: https://lore.kernel.org/r/acb7f612-df26-4e2a-a35d-7cd040f513e1@samba.org/ Signed-off-by: David Howells dhowells@redhat.com Reviewed-by: Stefan Metzmacher metze@samba.org Tested-by: Stefan Metzmacher metze@samba.org cc: Paulo Alcantara pc@manguebit.com cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/smbdirect.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
--- a/fs/smb/client/smbdirect.c +++ b/fs/smb/client/smbdirect.c @@ -1452,6 +1452,9 @@ static int allocate_caches_and_workqueue char name[MAX_NAME_LEN]; int rc;
+ if (WARN_ON_ONCE(sp->max_recv_size < sizeof(struct smbdirect_data_transfer))) + return -ENOMEM; + scnprintf(name, MAX_NAME_LEN, "smbd_request_%p", info); info->request_cache = kmem_cache_create( @@ -1469,12 +1472,17 @@ static int allocate_caches_and_workqueue goto out1;
scnprintf(name, MAX_NAME_LEN, "smbd_response_%p", info); + + struct kmem_cache_args response_args = { + .align = __alignof__(struct smbd_response), + .useroffset = (offsetof(struct smbd_response, packet) + + sizeof(struct smbdirect_data_transfer)), + .usersize = sp->max_recv_size - sizeof(struct smbdirect_data_transfer), + }; info->response_cache = - kmem_cache_create( - name, - sizeof(struct smbd_response) + - sp->max_recv_size, - 0, SLAB_HWCACHE_ALIGN, NULL); + kmem_cache_create(name, + sizeof(struct smbd_response) + sp->max_recv_size, + &response_args, SLAB_HWCACHE_ALIGN); if (!info->response_cache) goto out2;