Re: [PATCH net,v7] net/smc: prevent NULL pointer dereference in txopt_get

[Eric Dumazet]

On Thu, Aug 29, 2024 at 5:57 AM Jeongjun Park <aha310510@xxxxxxxxx> wrote:
>
> Since smc_inet6_prot does not initialize ipv6_pinfo_offset, inet6_create()
> copies an incorrect address value, sk + 0 (offset), to inet_sk(sk)->pinet6.
>
> In addition, since inet_sk(sk)->pinet6 and smc_sk(sk)->clcsock practically
> point to the same address, when smc_create_clcsk() stores the newly
> created clcsock in smc_sk(sk)->clcsock, inet_sk(sk)->pinet6 is corrupted
> into clcsock. This causes NULL pointer dereference and various other
> memory corruptions.
>
> To solve this problem, you need to initialize ipv6_pinfo_offset, add a
> smc6_sock structure, and then add ipv6_pinfo as the second member of
> the smc_sock structure.
>
> Reported-by: syzkaller <syzkaller@xxxxxxxxxxxxxxxx>
> Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC")
> Signed-off-by: Jeongjun Park <aha310510@xxxxxxxxx>

Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>