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authorDavid Howells <dhowells@redhat.com>2018-02-16 01:59:00 +0300
committerDavid S. Miller <davem@davemloft.net>2018-02-17 00:22:27 +0300
commita16b8d0cf2ec1e626d24bc2a7b9e64ace6f7501d (patch)
treeed1d728ec60ce107133826d923c809fa99b4c6c3 /net/rxrpc/recvmsg.c
parent43a08e0f58b3f236165029710a4e3b303815253b (diff)
downloadlinux-a16b8d0cf2ec1e626d24bc2a7b9e64ace6f7501d.tar.xz
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/rxrpc/recvmsg.c')
-rw-r--r--net/rxrpc/recvmsg.c5
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;