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[ Upstream commit 5171b37d959641bbc619781caf62e61f7b940871 ] In order to remove the race caught by syzbot [1], we need to lock the socket before using po->tp_version as this could change under us otherwise. This means lock_sock() and release_sock() must be done by packet_set_ring() callers. [1] : BUG: KMSAN: uninit-value in packet_set_ring+0x1254/0x3870 net/packet/af_packet.c:4249 CPU: 0 PID: 20195 Comm: syzkaller707632 Not tainted 4.16.0+ #83 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x185/0x1d0 lib/dump_stack.c:53 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 packet_set_ring+0x1254/0x3870 net/packet/af_packet.c:4249 packet_setsockopt+0x12c6/0x5a90 net/packet/af_packet.c:3662 SYSC_setsockopt+0x4b8/0x570 net/socket.c:1849 SyS_setsockopt+0x76/0xa0 net/socket.c:1828 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x449099 RSP: 002b:00007f42b5307ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 000000000070003c RCX: 0000000000449099 RDX: 0000000000000005 RSI: 0000000000000107 RDI: 0000000000000003 RBP: 0000000000700038 R08: 000000000000001c R09: 0000000000000000 R10: 00000000200000c0 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000080eecf R14: 00007f42b53089c0 R15: 0000000000000001 Local variable description: ----req_u@packet_setsockopt Variable was created at: packet_setsockopt+0x13f/0x5a90 net/packet/af_packet.c:3612 SYSC_setsockopt+0x4b8/0x570 net/socket.c:1849 Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.