github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-10-23 23:51:02 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

net/mctp: publish the mctp_dev only after it is initialised

Browse Source 
mctp_add_dev() links the new mctp_dev into dev->mctp_ptr before mdev->dev
is assigned, so a reader that picks the device up in that window
dereferences a net_device pointer that is still NULL:

KASAN: null-ptr-deref in range [0x00000000000000b0-0x00000000000000b7]
Call Trace:
 <TASK>
 ? __pfx_mctp_sendmsg (./include/linux/sockptr.h:49)
 ? __pfx_mctp_dst_output (net/mctp/route.c:41)
 ? selinux_socket_sendmsg (security/selinux/hooks.c:5278)
 ____sys_sendmsg (net/socket.c:775 (discriminator 1) net/socket.c:790
 (discriminator 1) net/socket.c:2684 (discriminator 1))
 ? __pfx_____sys_sendmsg (net/socket.c:1131)
 ? __pfx_copy_msghdr_from_user (net/socket.c:2590)
 ? update_cfs_rq_load_avg (kernel/sched/fair.c:5478)
 ___sys_sendmsg (net/socket.c:2738)
 ? __pfx____sys_sendmsg (net/socket.c:2625)
 ? perf_event_task_tick (./include/linux/rcupdate.h:838)
 ? sched_tick (kernel/sched/core.c:5818)
 ? clockevents_program_event (kernel/time/clockevents.c:372)
 ? fdget (./include/linux/rcupdate.h:873 fs/file.c:1100)
 __sys_sendmsg (net/socket.c:2770)
 ? __pfx___sys_sendmsg (net/socket.c:2751)
 do_syscall_64 (arch/x86/entry/syscall_64.c:63)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
 </TASK>

Fix by publishing only once the object is fully initialised:
__mctp_dev_get() runs under rcu_read_lock() only and hands
this object to readers as soon as mctp_ptr is assigned, so
they must never observe mdev->dev == NULL.

Fixes: 583be982d9 ("mctp: Add device handling and netlink interface")
Signed-off-by: Binbin Deng <18983559317@163.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/729830b8.130.1a0c945579d.Coremail.18983559317@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Binbin Deng 2026-09-22 21:19:19 +08:00 committed by Jakub Kicinski
parent 11536ee3d3
commit aadf655e8e
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
net/mctp/device.c
View File

@ -344,13 +344,13 @@ static struct mctp_dev *mctp_add_dev(struct net_device *dev)
mdev->net = mctp_default_net(dev_net(dev));
/* associate to net_device */
refcount_set(&mdev->refs, 1);
rcu_assign_pointer(dev->mctp_ptr, mdev);
dev_hold(dev);
mdev->dev = dev;
/* Associate to net_device, publish the mdev. */
rcu_assign_pointer(dev->mctp_ptr, mdev);
return mdev;
}