2024-03-07 14:24:13

by Gavrilov Ilia

Subject: [PATCH net-next v2 1/6] tcp: fix incorrect parameter validation in the do_tcp_getsockopt() function

The 'len' variable can't be negative when assigned the result of
'min_t' because all 'min_t' parameters are cast to unsigned int,
and then the minimum one is chosen.

To fix the logic, check 'len' as read from 'optlen',
where the types of relevant variables are (signed) int.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Gavrilov Ilia <[email protected]>
---
V2:
- reword the patch description

net/ipv4/tcp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c82dc42f57c6..a4f418592314 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4010,11 +4010,11 @@ int do_tcp_getsockopt(struct sock *sk, int level,
if (copy_from_sockptr(&len, optlen, sizeof(int)))
return -EFAULT;

- len = min_t(unsigned int, len, sizeof(int));
-
if (len < 0)
return -EINVAL;

+ len = min_t(unsigned int, len, sizeof(int));
+
switch (optname) {
case TCP_MAXSEG:
val = tp->mss_cache;
--
2.39.2

2024-03-08 03:44:45

by Jason Xing

Subject: Re: [PATCH net-next v2 1/6] tcp: fix incorrect parameter validation in the do_tcp_getsockopt() function

On Thu, Mar 7, 2024 at 10:44 PM Gavrilov Ilia <[email protected]> wrote:
>
> The 'len' variable can't be negative when assigned the result of
> 'min_t' because all 'min_t' parameters are cast to unsigned int,
> and then the minimum one is chosen.
>
> To fix the logic, check 'len' as read from 'optlen',
> where the types of relevant variables are (signed) int.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Gavrilov Ilia <[email protected]>

For the patch itself, please feel free to add:
Reviewed-by: Jason Xing <[email protected]>

I notice that you use Fixes meanwhile you target net-next. I'm not
sure if it's proper.

> ---
> V2:
> - reword the patch description
>
> net/ipv4/tcp.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index c82dc42f57c6..a4f418592314 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -4010,11 +4010,11 @@ int do_tcp_getsockopt(struct sock *sk, int level,
> if (copy_from_sockptr(&len, optlen, sizeof(int)))
> return -EFAULT;
>
> - len = min_t(unsigned int, len, sizeof(int));
> -
> if (len < 0)
> return -EINVAL;
>
> + len = min_t(unsigned int, len, sizeof(int));
> +
> switch (optname) {
> case TCP_MAXSEG:
> val = tp->mss_cache;
> --
> 2.39.2
>