Eric Dumazet e5dcc0c322 net: rose: fix a possible stack overflow ... rose_write_internal() uses a temp buffer of 100 bytes, but a manual inspection showed that given arbitrary input, rose_create_facilities() can fill up to 110 bytes. Lets use a tailroom of 256 bytes for peace of mind, and remove the bounce buffer : we can simply allocate a big enough skb and adjust its length as needed. syzbot report : BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:352 [inline] BUG: KASAN: stack-out-of-bounds in rose_create_facilities net/rose/rose_subr.c:521 [inline] BUG: KASAN: stack-out-of-bounds in rose_write_internal+0x597/0x15d0 net/rose/rose_subr.c:116 Write of size 7 at addr ffff88808b1ffbef by task syz-executor.0/24854 CPU: 0 PID: 24854 Comm: syz-executor.0 Not tainted 5.0.0+ #97 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x123/0x190 mm/kasan/generic.c:191 memcpy+0x38/0x50 mm/kasan/common.c:131 memcpy include/linux/string.h:352 [inline] rose_create_facilities net/rose/rose_subr.c:521 [inline] rose_write_internal+0x597/0x15d0 net/rose/rose_subr.c:116 rose_connect+0x7cb/0x1510 net/rose/af_rose.c:826 __sys_connect+0x266/0x330 net/socket.c:1685 __do_sys_connect net/socket.c:1696 [inline] __se_sys_connect net/socket.c:1693 [inline] __x64_sys_connect+0x73/0xb0 net/socket.c:1693 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458079 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f47b8d9dc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458079 RDX: 000000000000001c RSI: 0000000020000040 RDI: 0000000000000004 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f47b8d9e6d4 R13: 00000000004be4a4 R14: 00000000004ceca8 R15: 00000000ffffffff The buggy address belongs to the page: page:ffffea00022c7fc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x1fffc0000000000() raw: 01fffc0000000000 0000000000000000 ffffffff022c0101 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808b1ffa80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88808b1ffb00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 03 >ffff88808b1ffb80: f2 f2 00 00 00 00 00 00 00 00 00 00 00 00 04 f3 ^ ffff88808b1ffc00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 ffff88808b1ffc80: 00 00 00 00 00 00 00 f1 f1 f1 f1 f1 f1 01 f2 01 Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2019-03-18 16:53:22 -07:00
..
af_rose.c	net: rose: add missing dev_put() on error in rose_bind	2019-02-19 13:22:46 -08:00
Makefile
rose_dev.c	net: Kill dev_rebuild_header	2015-03-02 16:43:41 -05:00
rose_in.c	net: rose: mark expected switch fall-throughs	2017-10-22 02:02:26 +01:00
rose_link.c	treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts	2017-11-21 16:35:54 -08:00
rose_loopback.c	net/rose: Convert timers to use timer_setup()	2017-10-18 12:39:36 +01:00
rose_out.c	Remove all #inclusions of asm/system.h	2012-03-28 18:30:03 +01:00
rose_route.c	net/rose: fix NULL ax25_cb kernel panic	2019-01-27 10:40:01 -08:00
rose_subr.c	net: rose: fix a possible stack overflow	2019-03-18 16:53:22 -07:00
rose_timer.c	treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts	2017-11-21 16:35:54 -08:00
sysctl_net_rose.c	net: Convert uses of typedef ctl_table to struct ctl_table	2013-06-13 02:36:09 -07:00