That's my bad. Thank you for your comment and effort. Regards, Kyungtae Kim
On Wed, Jan 23, 2019 at 4:34 PM Willem de Bruijn <willemdebruijn.ker...@gmail.com> wrote: > > On Mon, Jan 21, 2019 at 2:25 PM Kyungtae Kim <kt0...@gmail.com> wrote: > > > > I'm reporting a bug in linux-5.0-rc2: "UBSAN: Undefined behaviour in > > net/ipv4/ip_output.c" > > > > kernel config: https://kt0755.github.io/etc/config-5.0-rc2 > > repro: https://kt0755.github.io/etc/repro.b6a11.c > > Thanks for the report. > > That reproducer does not seem to exercise system call sendmsg. Did you > mean to share another? Perhaps one that users SO_SNDBUFFORCE or > sysctl_wmem_max. > > When constructing a reproducer, I did easily trigger an UBSAN warning > when setting SO_SNDBUFFORCE to INT_MAX - 1, so I can imagine that this > one can trigger, as well. As long as sk_sndbuf can be set to any > integer value, we'll have to be careful with any such multiplication. > > > Integer overflow happened in __ip_append_data() when 2 * sk->sk_sndbuf > > (at line 1004) > > is larger than the boundary of the destination (i.e., int). > > Some sanity check code right before it would help. > > > > ========================================= > > UBSAN: Undefined behaviour in net/ipv4/ip_output.c:1004:11 > > signed integer overflow: > > 1282607372 * 2 cannot be represented in type 'int' > > CPU: 0 PID: 8465 Comm: syz-executor4 Not tainted 5.0.0-rc2 #1 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0xb1/0x118 lib/dump_stack.c:113 > > ubsan_epilogue+0x12/0x94 lib/ubsan.c:159 > > handle_overflow+0x1cf/0x21a lib/ubsan.c:190 > > __ubsan_handle_mul_overflow+0x2a/0x35 lib/ubsan.c:214 > > __ip_append_data+0x30ed/0x3350 net/ipv4/ip_output.c:1004 > > ip_append_data.part.18+0xf3/0x170 net/ipv4/ip_output.c:1220 > > ip_append_data+0x63/0x80 net/ipv4/ip_output.c:1209 > > raw_sendmsg+0xd99/0x2b60 net/ipv4/raw.c:670 > > inet_sendmsg+0xfc/0x620 net/ipv4/af_inet.c:798 > > sock_sendmsg_nosec net/socket.c:621 [inline] > > sock_sendmsg+0xdd/0x130 net/socket.c:631 > > ___sys_sendmsg+0x7b3/0x950 net/socket.c:2116 > > __sys_sendmsg+0xfc/0x1d0 net/socket.c:2154 > > __do_sys_sendmsg net/socket.c:2163 [inline] > > __se_sys_sendmsg net/socket.c:2161 [inline] > > __x64_sys_sendmsg+0x83/0xc0 net/socket.c:2161 > > do_syscall_64+0xbe/0x4f0 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x4497b9 > > Code: e8 8c 9f 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 > > 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d > > 01 f0 ff ff 0f 83 9b 6b fc ff c3 66 2e 0f 1f 84 00 00 00 00 > > RSP: 002b:00007f0d0100bc68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > > RAX: ffffffffffffffda RBX: 00007f0d0100c6cc RCX: 00000000004497b9 > > RDX: 0000000000000000 RSI: 0000000020000500 RDI: 0000000000000013 > > RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > > R13: 00000000000089a0 R14: 00000000006f1a40 R15: 00007f0d0100c700 > > ========================================= > > > > Thanks, > > Kyungtae
