Alexander Potapenko 540e2894f7 net: don't call strlen() on the user buffer in packet_bind_spkt() ... KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of uninitialized memory in packet_bind_spkt(): Acked-by: Eric Dumazet <edumazet@google.com> ================================================================== BUG: KMSAN: use of unitialized memory CPU: 0 PID: 1074 Comm: packet Not tainted 4.8.0-rc6+ #1891 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 0000000000000000 ffff88006b6dfc08 ffffffff82559ae8 ffff88006b6dfb48 ffffffff818a7c91 ffffffff85b9c870 0000000000000092 ffffffff85b9c550 0000000000000000 0000000000000092 00000000ec400911 0000000000000002 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff82559ae8>] dump_stack+0x238/0x290 lib/dump_stack.c:51 [<ffffffff818a6626>] kmsan_report+0x276/0x2e0 mm/kmsan/kmsan.c:1003 [<ffffffff818a783b>] __msan_warning+0x5b/0xb0 mm/kmsan/kmsan_instr.c:424 [< inline >] strlen lib/string.c:484 [<ffffffff8259b58d>] strlcpy+0x9d/0x200 lib/string.c:144 [<ffffffff84b2eca4>] packet_bind_spkt+0x144/0x230 net/packet/af_packet.c:3132 [<ffffffff84242e4d>] SYSC_bind+0x40d/0x5f0 net/socket.c:1370 [<ffffffff84242a22>] SyS_bind+0x82/0xa0 net/socket.c:1356 [<ffffffff8515991b>] entry_SYSCALL_64_fastpath+0x13/0x8f arch/x86/entry/entry_64.o:? chained origin: 00000000eba00911 [<ffffffff810bb787>] save_stack_trace+0x27/0x50 arch/x86/kernel/stacktrace.c:67 [< inline >] kmsan_save_stack_with_flags mm/kmsan/kmsan.c:322 [< inline >] kmsan_save_stack mm/kmsan/kmsan.c:334 [<ffffffff818a59f8>] kmsan_internal_chain_origin+0x118/0x1e0 mm/kmsan/kmsan.c:527 [<ffffffff818a7773>] __msan_set_alloca_origin4+0xc3/0x130 mm/kmsan/kmsan_instr.c:380 [<ffffffff84242b69>] SYSC_bind+0x129/0x5f0 net/socket.c:1356 [<ffffffff84242a22>] SyS_bind+0x82/0xa0 net/socket.c:1356 [<ffffffff8515991b>] entry_SYSCALL_64_fastpath+0x13/0x8f arch/x86/entry/entry_64.o:? origin description: ----address@SYSC_bind (origin=00000000eb400911) ================================================================== (the line numbers are relative to 4.8-rc6, but the bug persists upstream) , when I run the following program as root: ===================================== #include <string.h> #include <sys/socket.h> #include <netpacket/packet.h> #include <net/ethernet.h> int main() { struct sockaddr addr; memset(&addr, 0xff, sizeof(addr)); addr.sa_family = AF_PACKET; int fd = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ALL)); bind(fd, &addr, sizeof(addr)); return 0; } ===================================== This happens because addr.sa_data copied from the userspace is not zero-terminated, and copying it with strlcpy() in packet_bind_spkt() results in calling strlen() on the kernel copy of that non-terminated buffer. Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2017-03-01 20:55:57 -08:00
..
af_packet.c	net: don't call strlen() on the user buffer in packet_bind_spkt()	2017-03-01 20:55:57 -08:00
diag.c	packet: pdiag_put_ring() should return TX_RING info for TPACKET_V3	2017-01-10 21:02:42 -05:00
internal.h	packet: add classic BPF fanout mode	2015-08-17 14:22:47 -07:00
Kconfig	packet: Diag core and basic socket info dumping	2012-08-14 16:56:33 -07:00
Makefile	packet: Diag core and basic socket info dumping	2012-08-14 16:56:33 -07:00