diff options
| author | David Howells <dhowells@redhat.com> | 2018-02-15 22:59:00 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-02-16 16:22:27 -0500 |
| commit | a16b8d0cf2ec1e626d24bc2a7b9e64ace6f7501d (patch) | |
| tree | ed1d728ec60ce107133826d923c809fa99b4c6c3 /net | |
| parent | 43a08e0f58b3f236165029710a4e3b303815253b (diff) | |
rxrpc: Work around usercopy check
Due to a check recently added to copy_to_user(), it's now not permitted to
copy from slab-held data to userspace unless the slab is whitelisted. This
affects rxrpc_recvmsg() when it attempts to place an RXRPC_USER_CALL_ID
control message in the userspace control message buffer. A warning is
generated by usercopy_warn() because the source is the copy of the
user_call_ID retained in the rxrpc_call struct.
Work around the issue by copying the user_call_ID to a variable on the
stack and passing that to put_cmsg().
The warning generated looks like:
Bad or missing usercopy whitelist? Kernel memory exposure attempt detected from SLUB object 'dmaengine-unmap-128' (offset 680, size 8)!
WARNING: CPU: 0 PID: 1401 at mm/usercopy.c:81 usercopy_warn+0x7e/0xa0
...
RIP: 0010:usercopy_warn+0x7e/0xa0
...
Call Trace:
__check_object_size+0x9c/0x1a0
put_cmsg+0x98/0x120
rxrpc_recvmsg+0x6fc/0x1010 [rxrpc]
? finish_wait+0x80/0x80
___sys_recvmsg+0xf8/0x240
? __clear_rsb+0x25/0x3d
? __clear_rsb+0x15/0x3d
? __clear_rsb+0x25/0x3d
? __clear_rsb+0x15/0x3d
? __clear_rsb+0x25/0x3d
? __clear_rsb+0x15/0x3d
? __clear_rsb+0x25/0x3d
? __clear_rsb+0x15/0x3d
? finish_task_switch+0xa6/0x2b0
? trace_hardirqs_on_caller+0xed/0x180
? _raw_spin_unlock_irq+0x29/0x40
? __sys_recvmsg+0x4e/0x90
__sys_recvmsg+0x4e/0x90
do_syscall_64+0x7a/0x220
entry_SYSCALL_64_after_hwframe+0x26/0x9b
Reported-by: Jonathan Billings <jsbillings@jsbillings.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Jonathan Billings <jsbillings@jsbillings.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/rxrpc/recvmsg.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c index cc21e8db25b0..9d45d8b56744 100644 --- a/net/rxrpc/recvmsg.c +++ b/net/rxrpc/recvmsg.c @@ -517,9 +517,10 @@ try_again: ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID, sizeof(unsigned int), &id32); } else { + unsigned long idl = call->user_call_ID; + ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID, - sizeof(unsigned long), - &call->user_call_ID); + sizeof(unsigned long), &idl); } if (ret < 0) goto error_unlock_call; |