4.7-stable review patch. If anyone has any objections, please let me know.
------------------
From: WANG Cong <xiyou.wangcong@xxxxxxxxx>
[ Upstream commit c0338aff2260ea6c092806312dbb154cec07a242 ]
Dmitry reported a double free on kcm socket, which could
be easily reproduced by:
#include <unistd.h>
#include <sys/syscall.h>
int main()
{
int fd = syscall(SYS_socket, 0x29ul, 0x5ul, 0x0ul, 0, 0, 0);
syscall(SYS_ioctl, fd, 0x89e2ul, 0x20a98000ul, 0, 0, 0);
return 0;
}
This is because on the error path, after we install
the new socket file, we call sock_release() to clean
up the socket, which leaves the fd pointing to a freed
socket. Fix this by calling sys_close() on that fd
directly.
Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module")
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Tom Herbert <tom@xxxxxxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/kcm/kcmsock.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -13,6 +13,7 @@
#include <linux/socket.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
+#include <linux/syscalls.h>
#include <net/kcm.h>
#include <net/netns/generic.h>
#include <net/sock.h>
@@ -2035,7 +2036,7 @@ static int kcm_ioctl(struct socket *sock
if (copy_to_user((void __user *)arg, &info,
sizeof(info))) {
err = -EFAULT;
- sock_release(newsock);
+ sys_close(info.fd);
}
}
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