linux-kernel - [PATCH] Fixes the null pointer deferences in nsim

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Message-Id: <20231110084425.2123-1-kdipendra88@gmail.com>
Date:   Fri, 10 Nov 2023 08:44:26 +0000
From:   Dipendra Khadka <kdipendra88@...il.com>
To:     kuba@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        pabeni@...hat.com
Cc:     Dipendra Khadka <kdipendra88@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        syzbot+44c2416196b7c607f226@...kaller.appspotmail.com
Subject: [PATCH] Fixes the null pointer deferences in nsim_bpf

Syzkaller found a null pointer dereference in nsim_bpf
originating from the lack of a null check for state.

This patch fixes the issue by adding a check for state
in two functions nsim_prog_set_loaded and nsim_setup_prog_hw_checks

Reported-by: syzbot+44c2416196b7c607f226@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com./bug?extid=44c2416196b7c607f226

Signed-off-by: Dipendra Khadka <kdipendra88@...il.com>
---
 drivers/net/netdevsim/bpf.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index f60eb97e3a62..e407efb0e3de 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -97,7 +97,8 @@ static void nsim_prog_set_loaded(struct bpf_prog *prog, bool loaded)
 		return;
 
 	state = prog->aux->offload->dev_priv;
-	state->is_loaded = loaded;
+	if (state)
+		state->is_loaded = loaded;
 }
 
 static int
@@ -317,10 +318,12 @@ nsim_setup_prog_hw_checks(struct netdevsim *ns, struct netdev_bpf *bpf)
 	}
 
 	state = bpf->prog->aux->offload->dev_priv;
-	if (WARN_ON(strcmp(state->state, "xlated"))) {
-		NSIM_EA(bpf->extack, "offloading program in bad state");
-		return -EINVAL;
-	}
+	if (state) {
+		if (WARN_ON(strcmp(state->state, "xlated"))) {
+			NSIM_EA(bpf->extack, "offloading program in bad state");
+			return -EINVAL;
+		}
+	}
 	return 0;
 }
 
-- 
2.34.1