CVE-2025-21716

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

vxlan: Fix uninit-value in vxlanvnifilterdump()

KMSAN reported an uninit-value access in vxlanvnifilterdump() [1].

If the length of the netlink message payload is less than sizeof(struct tunnelmsg), vxlanvnifilter_dump() accesses bytes beyond the message. This can lead to uninit-value access. Fix this by returning an error in such situations.

[1] BUG: KMSAN: uninit-value in vxlanvnifilterdump+0x328/0x920 drivers/net/vxlan/vxlanvnifilter.c:422 vxlanvnifilterdump+0x328/0x920 drivers/net/vxlan/vxlanvnifilter.c:422 rtnldumpit+0xd5/0x2f0 net/core/rtnetlink.c:6786 netlinkdump+0x93e/0x15f0 net/netlink/afnetlink.c:2317 netlinkdumpstart+0x716/0xd60 net/netlink/afnetlink.c:2432 netlinkdumpstart include/linux/netlink.h:340 [inline] rtnetlinkdumpstart net/core/rtnetlink.c:6815 [inline] rtnetlinkrcvmsg+0x1256/0x14a0 net/core/rtnetlink.c:6882 netlinkrcvskb+0x467/0x660 net/netlink/afnetlink.c:2542 rtnetlinkrcv+0x35/0x40 net/core/rtnetlink.c:6944 netlinkunicastkernel net/netlink/afnetlink.c:1321 [inline] netlinkunicast+0xed6/0x1290 net/netlink/afnetlink.c:1347 netlinksendmsg+0x1092/0x1230 net/netlink/afnetlink.c:1891 socksendmsgnosec net/socket.c:711 [inline] _socksendmsg+0x330/0x3d0 net/socket.c:726 _syssendmsg+0x7f4/0xb50 net/socket.c:2583 _syssendmsg+0x271/0x3b0 net/socket.c:2637 _syssendmsg net/socket.c:2669 [inline] _dosyssendmsg net/socket.c:2674 [inline] _sesyssendmsg net/socket.c:2672 [inline] _x64syssendmsg+0x211/0x3e0 net/socket.c:2672 x64syscall+0x3878/0x3d90 arch/x86/include/generated/asm/syscalls64.h:47 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0xd9/0x1d0 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x77/0x7f

Uninit was created at: slabpostallochook mm/slub.c:4110 [inline] slaballocnode mm/slub.c:4153 [inline] kmemcacheallocnodenoprof+0x800/0xe80 mm/slub.c:4205 kmallocreserve+0x13b/0x4b0 net/core/skbuff.c:587 allocskb+0x347/0x7d0 net/core/skbuff.c:678 allocskb include/linux/skbuff.h:1323 [inline] netlinkalloclargeskb+0xa5/0x280 net/netlink/afnetlink.c:1196 netlinksendmsg+0xac9/0x1230 net/netlink/afnetlink.c:1866 socksendmsgnosec net/socket.c:711 [inline] _socksendmsg+0x330/0x3d0 net/socket.c:726 syssendmsg+0x7f4/0xb50 net/socket.c:2583 _syssendmsg+0x271/0x3b0 net/socket.c:2637 _syssendmsg net/socket.c:2669 [inline] _dosyssendmsg net/socket.c:2674 [inline] _sesyssendmsg net/socket.c:2672 [inline] _x64syssendmsg+0x211/0x3e0 net/socket.c:2672 x64syscall+0x3878/0x3d90 arch/x86/include/generated/asm/syscalls64.h:47 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0xd9/0x1d0 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 30991 Comm: syz.4.10630 Not tainted 6.12.0-10694-gc44daa7e3c73 #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014