Some IPMI modules (e.g. ibmpex_msg_handler()) will have ipmi_usr_hdlr handlers that call ipmi_free_recv_msg() directly. This will essentially kfree(msg), leading to use-after-free.

This does not happen in the ipmi_devintf module, which will queue the message and run ipmi_free_recv_msg() later.

BUG: KASAN: use-after-free in deliver_response+0x12f/0x1b0 Read of size 8 at addr ffff888a7bf20018 by task ksoftirqd/3/27 CPU: 3 PID: 27 Comm: ksoftirqd/3 Tainted: G O 4.19.11-amd64-ani99-debug #12.0.1.601133+pv Hardware name: AppNeta r1000/X11SPW-TF, BIOS 2.1a-AP 09/17/2018 Call Trace: dump_stack+0x92/0xeb print_address_description+0x73/0x290 kasan_report+0x258/0x380 deliver_response+0x12f/0x1b0 ? ipmi_free_recv_msg+0x50/0x50 deliver_local_response+0xe/0x50 handle_one_recv_msg+0x37a/0x21d0 handle_new_recv_msgs+0x1ce/0x440 ...

Allocated by task 9885: kasan_kmalloc+0xa0/0xd0 kmem_cache_alloc_trace+0x116/0x290 ipmi_alloc_recv_msg+0x28/0x70 i_ipmi_request+0xb4a/0x1640 ipmi_request_settime+0x1b8/0x1e0 ...

Freed by task 27: __kasan_slab_free+0x12e/0x180 kfree+0xe9/0x280 deliver_response+0x122/0x1b0 deliver_local_response+0xe/0x50 handle_one_recv_msg+0x37a/0x21d0 handle_new_recv_msgs+0x1ce/0x440 tasklet_action_common.isra.19+0xc4/0x250 __do_softirq+0x11f/0x51f

Fixes: e86ee2d44b4 ("ipmi: Rework locking and shutdown for hot remove") Signed-off-by: Fred Klassen fklassen@appneta.com

--- drivers/char/ipmi/ipmi_msghandler.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index 7fc9612070a1..fbf93c2d6c05 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -883,7 +883,7 @@ static int deliver_response(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)

if (user) { user->handler->ipmi_recv_hndl(msg, user->handler_data); - release_ipmi_user(msg->user, index); + release_ipmi_user(user, index); } else { /* User went away, give up. */ ipmi_free_recv_msg(msg);