| From foo@baz Thu Mar 28 23:25:55 CET 2019 |
| From: Eric Dumazet <edumazet@google.com> |
| Date: Fri, 15 Mar 2019 10:41:14 -0700 |
| Subject: net: rose: fix a possible stack overflow |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| [ Upstream commit e5dcc0c3223c45c94100f05f28d8ef814db3d82c ] |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/rose/rose_subr.c | 21 ++++++++++++--------- |
| 1 file changed, 12 insertions(+), 9 deletions(-) |
| |
| --- a/net/rose/rose_subr.c |
| +++ b/net/rose/rose_subr.c |
| @@ -105,16 +105,17 @@ void rose_write_internal(struct sock *sk |
| struct sk_buff *skb; |
| unsigned char *dptr; |
| unsigned char lci1, lci2; |
| - char buffer[100]; |
| - int len, faclen = 0; |
| + int maxfaclen = 0; |
| + int len, faclen; |
| + int reserve; |
| |
| - len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 1; |
| + reserve = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 1; |
| + len = ROSE_MIN_LEN; |
| |
| switch (frametype) { |
| case ROSE_CALL_REQUEST: |
| len += 1 + ROSE_ADDR_LEN + ROSE_ADDR_LEN; |
| - faclen = rose_create_facilities(buffer, rose); |
| - len += faclen; |
| + maxfaclen = 256; |
| break; |
| case ROSE_CALL_ACCEPTED: |
| case ROSE_CLEAR_REQUEST: |
| @@ -123,15 +124,16 @@ void rose_write_internal(struct sock *sk |
| break; |
| } |
| |
| - if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL) |
| + skb = alloc_skb(reserve + len + maxfaclen, GFP_ATOMIC); |
| + if (!skb) |
| return; |
| |
| /* |
| * Space for AX.25 header and PID. |
| */ |
| - skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 1); |
| + skb_reserve(skb, reserve); |
| |
| - dptr = skb_put(skb, skb_tailroom(skb)); |
| + dptr = skb_put(skb, len); |
| |
| lci1 = (rose->lci >> 8) & 0x0F; |
| lci2 = (rose->lci >> 0) & 0xFF; |
| @@ -146,7 +148,8 @@ void rose_write_internal(struct sock *sk |
| dptr += ROSE_ADDR_LEN; |
| memcpy(dptr, &rose->source_addr, ROSE_ADDR_LEN); |
| dptr += ROSE_ADDR_LEN; |
| - memcpy(dptr, buffer, faclen); |
| + faclen = rose_create_facilities(dptr, rose); |
| + skb_put(skb, faclen); |
| dptr += faclen; |
| break; |
| |