netdev - [PATCH bpf-next] bpf: Handle NULL in bpf_local_storage

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Message-Id: <20230412171252.15635-1-alexei.starovoitov@gmail.com>
Date:   Wed, 12 Apr 2023 10:12:52 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     davem@...emloft.net
Cc:     daniel@...earbox.net, andrii@...nel.org, martin.lau@...nel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org, kernel-team@...com
Subject: [PATCH bpf-next] bpf: Handle NULL in bpf_local_storage_free.

From: Alexei Starovoitov <ast@...nel.org>

During OOM bpf_local_storage_alloc() may fail to allocate 'storage' and
call to bpf_local_storage_free() with NULL pointer will cause a crash like:
[ 271718.917646] BUG: kernel NULL pointer dereference, address: 00000000000000a0
[ 271719.019620] RIP: 0010:call_rcu+0x2d/0x240
[ 271719.216274]  bpf_local_storage_alloc+0x19e/0x1e0
[ 271719.250121]  bpf_local_storage_update+0x33b/0x740

Fixes: 7e30a8477b0b ("bpf: Add bpf_local_storage_free()")
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
 kernel/bpf/bpf_local_storage.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index dab2ff4c99d9..47d9948d768f 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c
@@ -157,6 +157,9 @@ static void bpf_local_storage_free(struct bpf_local_storage *local_storage,
 				   struct bpf_local_storage_map *smap,
 				   bool bpf_ma, bool reuse_now)
 {
+	if (!local_storage)
+		return;
+
 	if (!bpf_ma) {
 		__bpf_local_storage_free(local_storage, reuse_now);
 		return;
-- 
2.34.1