CVE-2021-47597

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

inet_diag: fix kernel-infoleak for UDP sockets

KMSAN reported a kernel-infoleak [1], that can exploited by unpriv users.

After analysis it turned out UDP was not initializing r->idiagexpires. Other users of inetskdiagfill() might make the same mistake in the future, so fix this in inetskdiag_fill().

[1] BUG: KMSAN: kernel-infoleak in instrumentcopytouser include/linux/instrumented.h:121 [inline] BUG: KMSAN: kernel-infoleak in copyout lib/ioviter.c:156 [inline] BUG: KMSAN: kernel-infoleak in copytoiter+0x69d/0x25c0 lib/ioviter.c:670 instrumentcopytouser include/linux/instrumented.h:121 [inline] copyout lib/ioviter.c:156 [inline] copytoiter+0x69d/0x25c0 lib/ioviter.c:670 copytoiter include/linux/uio.h:155 [inline] simplecopytoiter+0xf3/0x140 net/core/datagram.c:519 _skbdatagramiter+0x2cb/0x1280 net/core/datagram.c:425 skbcopydatagramiter+0xdc/0x270 net/core/datagram.c:533 skbcopydatagrammsg include/linux/skbuff.h:3657 [inline] netlinkrecvmsg+0x660/0x1c60 net/netlink/afnetlink.c:1974 sockrecvmsgnosec net/socket.c:944 [inline] sockrecvmsg net/socket.c:962 [inline] sockreaditer+0x5a9/0x630 net/socket.c:1035 callreaditer include/linux/fs.h:2156 [inline] newsyncread fs/readwrite.c:400 [inline] vfsread+0x1631/0x1980 fs/readwrite.c:481 ksysread+0x28c/0x520 fs/readwrite.c:619 _dosysread fs/readwrite.c:629 [inline] _sesysread fs/readwrite.c:627 [inline] _x64sysread+0xdb/0x120 fs/readwrite.c:627 dosyscallx64 arch/x86/entry/common.c:51 [inline] dosyscall64+0x54/0xd0 arch/x86/entry/common.c:82 entrySYSCALL64afterhwframe+0x44/0xae

Uninit was created at: slabpostallochook mm/slab.h:524 [inline] slaballocnode mm/slub.c:3251 [inline] _kmallocnodetrackcaller+0xe0c/0x1510 mm/slub.c:4974 kmallocreserve net/core/skbuff.c:354 [inline] _allocskb+0x545/0xf90 net/core/skbuff.c:426 allocskb include/linux/skbuff.h:1126 [inline] netlinkdump+0x3d5/0x16a0 net/netlink/afnetlink.c:2245 _netlinkdumpstart+0xd1c/0xee0 net/netlink/afnetlink.c:2370 netlinkdumpstart include/linux/netlink.h:254 [inline] inetdiaghandlercmd+0x2e7/0x400 net/ipv4/inetdiag.c:1343 sockdiagrcvmsg+0x24a/0x620 netlinkrcvskb+0x447/0x800 net/netlink/afnetlink.c:2491 sockdiagrcv+0x63/0x80 net/core/sockdiag.c:276 netlinkunicastkernel net/netlink/afnetlink.c:1319 [inline] netlinkunicast+0x1095/0x1360 net/netlink/afnetlink.c:1345 netlinksendmsg+0x16f3/0x1870 net/netlink/afnetlink.c:1916 socksendmsgnosec net/socket.c:704 [inline] socksendmsg net/socket.c:724 [inline] sockwriteiter+0x594/0x690 net/socket.c:1057 doiterreadvwritev+0xa7f/0xc70 doiterwrite+0x52c/0x1500 fs/readwrite.c:851 vfswritev fs/readwrite.c:924 [inline] dowritev+0x63f/0xe30 fs/readwrite.c:967 _dosyswritev fs/readwrite.c:1040 [inline] _sesyswritev fs/readwrite.c:1037 [inline] _x64syswritev+0xe5/0x120 fs/readwrite.c:1037 dosyscallx64 arch/x86/entry/common.c:51 [inline] dosyscall64+0x54/0xd0 arch/x86/entry/common.c:82 entrySYSCALL64afterhwframe+0x44/0xae

Bytes 68-71 of 312 are uninitialized Memory access of size 312 starts at ffff88812ab54000 Data copied to user address 0000000020001440

CPU: 1 PID: 6365 Comm: syz-executor801 Not tainted 5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011