Manas <devnull+manas18244.iiitd.ac.in@xxxxxxxxxx> wrote: > The last parameter in __smc_diag_dump (struct nlattr *bc) is unused. > There is only one instance of this function being called and its passed > with a NULL value in place of bc. > > Signed-off-by: Manas <manas18244@xxxxxxxxxxx> > --- > The last parameter in __smc_diag_dump (struct nlattr *bc) is unused. > There is only one instance of this function being called and its passed > with a NULL value in place of bc. > > Though, the compiler (gcc) optimizes it. Looking at the object dump of > vmlinux (via `objdump -D vmlinux`), a new function clone > (__smc_diag_dump.constprop.0) is added which removes this parameter from > calling convention altogether. > > ffffffff8a701770 <__smc_diag_dump.constprop.0>: > ffffffff8a701770: 41 57 push %r15 > ffffffff8a701772: 41 56 push %r14 > ffffffff8a701774: 41 55 push %r13 > ffffffff8a701776: 41 54 push %r12 > > There are 5 parameters in original function, but in the cloned function > only 4. > > I believe this patch also fixes this oops bug[1], which arises in the > same function __smc_diag_dump. But I couldn't verify it further. Can > someone please test this? > > [1] https://syzkaller.appspot.com/bug?extid=271fed3ed6f24600c364 Unfortunately, I tested it myself and this bug is still triggering. Basically, this bug is not triggered in normal situations, but triggered when a race condition occurs, so I think the root cause is somewhere else. Regards, Jeongjun Park > --- > net/smc/smc_diag.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/net/smc/smc_diag.c b/net/smc/smc_diag.c > index 6fdb2d96777ad704c394709ec845f9ddef5e599a..8f7bd40f475945171a0afa5a2cce12d9aa2b1eb4 100644 > --- a/net/smc/smc_diag.c > +++ b/net/smc/smc_diag.c > @@ -71,8 +71,7 @@ static int smc_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb, > > static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb, > struct netlink_callback *cb, > - const struct smc_diag_req *req, > - struct nlattr *bc) > + const struct smc_diag_req *req) > { > struct smc_sock *smc = smc_sk(sk); > struct smc_diag_fallback fallback; > @@ -199,7 +198,6 @@ static int smc_diag_dump_proto(struct proto *prot, struct sk_buff *skb, > struct smc_diag_dump_ctx *cb_ctx = smc_dump_context(cb); > struct net *net = sock_net(skb->sk); > int snum = cb_ctx->pos[p_type]; > - struct nlattr *bc = NULL; > struct hlist_head *head; > int rc = 0, num = 0; > struct sock *sk; > @@ -214,7 +212,7 @@ static int smc_diag_dump_proto(struct proto *prot, struct sk_buff *skb, > continue; > if (num < snum) > goto next; > - rc = __smc_diag_dump(sk, skb, cb, nlmsg_data(cb->nlh), bc); > + rc = __smc_diag_dump(sk, skb, cb, nlmsg_data(cb->nlh)); > if (rc < 0) > goto out; > next: > > --- > base-commit: 59b723cd2adbac2a34fc8e12c74ae26ae45bf230 > change-id: 20241109-fix-oops-__smc_diag_dump-06ab3e9d39f4 > > Best regards, > -- > Manas <manas18244@xxxxxxxxxxx>
