4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
[ Upstream commit a98f91758995cb59611e61318dddd8a6956b52c3 ]
By setting certain socket options on ipv6 raw sockets, we can confuse the
length calculation in rawv6_push_pending_frames triggering a BUG_ON.
RIP: 0010:[<ffffffff817c6390>] [<ffffffff817c6390>] rawv6_sendmsg+0xc30/0xc40
RSP: 0018:ffff881f6c4a7c18 EFLAGS: 00010282
RAX: 00000000fffffff2 RBX: ffff881f6c681680 RCX: 0000000000000002
RDX: ffff881f6c4a7cf8 RSI: 0000000000000030 RDI: ffff881fed0f6a00
RBP: ffff881f6c4a7da8 R08: 0000000000000000 R09: 0000000000000009
R10: ffff881fed0f6a00 R11: 0000000000000009 R12: 0000000000000030
R13: ffff881fed0f6a00 R14: ffff881fee39ba00 R15: ffff881fefa93a80
Call Trace:
[<ffffffff8118ba23>] ? unmap_page_range+0x693/0x830
[<ffffffff81772697>] inet_sendmsg+0x67/0xa0
[<ffffffff816d93f8>] sock_sendmsg+0x38/0x50
[<ffffffff816d982f>] SYSC_sendto+0xef/0x170
[<ffffffff816da27e>] SyS_sendto+0xe/0x10
[<ffffffff81002910>] do_syscall_64+0x50/0xa0
[<ffffffff817f7cbc>] entry_SYSCALL64_slow_path+0x25/0x25
Handle by jumping to the failure path if skb_copy_bits gets an EFAULT.
Reproducer:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define LEN 504
int main(int argc, char* argv[])
{
int fd;
int zero = 0;
char buf[LEN];
memset(buf, 0, LEN);
fd = socket(AF_INET6, SOCK_RAW, 7);
setsockopt(fd, SOL_IPV6, IPV6_CHECKSUM, &zero, 4);
setsockopt(fd, SOL_IPV6, IPV6_DSTOPTS, &buf, LEN);
sendto(fd, buf, 1, 0, (struct sockaddr *) buf, 110);
}
Signed-off-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/raw.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -589,7 +589,11 @@ static int rawv6_push_pending_frames(str
}
offset += skb_transport_offset(skb);
- BUG_ON(skb_copy_bits(skb, offset, &csum, 2));
+ err = skb_copy_bits(skb, offset, &csum, 2);
+ if (err < 0) {
+ ip6_flush_pending_frames(sk);
+ goto out;
+ }
/* in case cksum was not initialized */
if (unlikely(csum))
--
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