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Miller" , Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , linux-kernel@vger.kernel.org Subject: [PATCH linux-next] ipv4: Fix NULL deference in fnhe_remove_oldest() Date: Thu, 2 Sep 2021 10:32:05 -0600 Message-Id: <20210902163205.17164-1-tim.gardner@canonical.com> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Coverity complains that linux-next commit 67d6d681e15b5 ("ipv4: make exception cache less predictible") neglected to check for NULL before dereferencing 'oldest'. It appears to be possible to fall through the for loop without ever setting 'oldest'. Cc: Eric Dumazet Cc: "David S. Miller" Cc: Hideaki YOSHIFUJI Cc: David Ahern Cc: Jakub Kicinski Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Tim Gardner --- net/ipv4/route.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index d6899ab5fb39..e85026591a09 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -603,9 +603,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } } - fnhe_flush_routes(oldest); - *oldest_p = oldest->fnhe_next; - kfree_rcu(oldest, rcu); + if (oldest) { + fnhe_flush_routes(oldest); + *oldest_p = oldest->fnhe_next; + kfree_rcu(oldest, rcu); + } } static u32 fnhe_hashfun(__be32 daddr) -- 2.33.0