| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.7 026/184] kcm: fix a socket double free | Date | Thu, 22 Sep 2016 19:39:20 +0200 |
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4.7-stable review patch. If anyone has any objections, please let me know.
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From: WANG Cong <xiyou.wangcong@gmail.com>
[ 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@google.com> Cc: Tom Herbert <tom@herbertland.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- 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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