CVE-2022-49636

In the Linux kernel, the following vulnerability has been resolved:

vlan: fix memory leak in vlan_newlink()

Blamed commit added back a bug I fixed in commit 9bbd917e0bec ("vlan: fix memory leak in vlandevsetegresspriority")

If a memory allocation fails in vlanchangelink() after other allocations succeeded, we need to call vlandevfreeegresspriority() to free all allocated memory because after a failed ->newlink() we do not call any methods like ndouninit() or dev->priv_destructor().

In following example, if the allocation for last element 2000:2001 fails, we need to free eight prior allocations:

ip link add link dummy0 dummy0.100 type vlan id 100 \ egress-qos-map 1:2 2:3 3:4 4:5 5:6 6:7 7:8 8:9 2000:2001

syzbot report was:

BUG: memory leak unreferenced object 0xffff888117bd1060 (size 32): comm "syz-executor408", pid 3759, jiffies 4294956555 (age 34.090s) hex dump (first 32 bytes): 09 00 00 00 00 a0 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff83fc60ad>] kmalloc include/linux/slab.h:600 [inline] [<ffffffff83fc60ad>] vlandevsetegresspriority+0xed/0x170 net/8021q/vlandev.c:193 [<ffffffff83fc6628>] vlanchangelink+0x178/0x1d0 net/8021q/vlannetlink.c:128 [<ffffffff83fc67c8>] vlannewlink+0x148/0x260 net/8021q/vlannetlink.c:185 [<ffffffff838b1278>] rtnlnewlinkcreate net/core/rtnetlink.c:3363 [inline] [<ffffffff838b1278>] rtnlnewlink+0xa58/0xdc0 net/core/rtnetlink.c:3580 [<ffffffff838b1629>] rtnlnewlink+0x49/0x70 net/core/rtnetlink.c:3593 [<ffffffff838ac66c>] rtnetlinkrcvmsg+0x21c/0x5c0 net/core/rtnetlink.c:6089 [<ffffffff839f9c37>] netlinkrcvskb+0x87/0x1d0 net/netlink/afnetlink.c:2501 [<ffffffff839f8da7>] netlinkunicastkernel net/netlink/afnetlink.c:1319 [inline] [<ffffffff839f8da7>] netlinkunicast+0x397/0x4c0 net/netlink/afnetlink.c:1345 [<ffffffff839f9266>] netlinksendmsg+0x396/0x710 net/netlink/afnetlink.c:1921 [<ffffffff8384dbf6>] socksendmsgnosec net/socket.c:714 [inline] [<ffffffff8384dbf6>] socksendmsg+0x56/0x80 net/socket.c:734 [<ffffffff8384e15c>] syssendmsg+0x36c/0x390 net/socket.c:2488 [<ffffffff838523cb>] _syssendmsg+0x8b/0xd0 net/socket.c:2542 [<ffffffff838525b8>] _syssendmsg net/socket.c:2571 [inline] [<ffffffff838525b8>] _dosyssendmsg net/socket.c:2580 [inline] [<ffffffff838525b8>] _sesyssendmsg net/socket.c:2578 [inline] [<ffffffff838525b8>] _x64syssendmsg+0x78/0xf0 net/socket.c:2578 [<ffffffff845ad8d5>] dosyscallx64 arch/x86/entry/common.c:50 [inline] [<ffffffff845ad8d5>] dosyscall64+0x35/0xb0 arch/x86/entry/common.c:80 [<ffffffff8460006a>] entrySYSCALL64after_hwframe+0x46/0xb0