From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 949F314D28C; Mon, 24 Feb 2025 14:48:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740408536; cv=none; b=TeFFwpUEDcxM4omBO1UgetpM245jCXflQRrbhk0nvEqfflv3sxX15QbBHxjCjSViE46X49tYnjBAQ5QMnlJLdlem3qG4LT/r4F9kV4mpxKmNcutRYW1xg9U/y7olgDN4zntYn+9qT3Bqc4cAls2B8jpZb+okuOuQxS/KT3+uxAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740408536; c=relaxed/simple; bh=gl5RxlkzqWde6d4/awpxZGHm3M7MQvBXKAxcaNu3n98=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DwYvYjzeWknztB+/4mgS486jzUpUbhsCzxR3Jn32RAnyOkTDjIjBWde/a+HImIpTXOG1BPeM1uWB5aWhDI2qPLs+576SQIfokyrEv3xvX8h6KxBRmEndJevKc0g6RyT7oSnbGH59upSRcpVhyyq73Aj501bDEnHq+obnDxetpoE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FDdFqPwm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FDdFqPwm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4693C4CED6; Mon, 24 Feb 2025 14:48:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1740408536; bh=gl5RxlkzqWde6d4/awpxZGHm3M7MQvBXKAxcaNu3n98=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FDdFqPwm4F8/2b+N6tyJoGR6DJVduiK8/i/TRfuxvISOcCDuuKuBkorxwYCJeBsIZ TB7SYLDp+9/qk5ln76doGg+XbUD84hQZGmgj4bxVk72bGPOLsROm5fGMnsKn1tllUH tNXdAoyVLyLZUDYP/GFVv8zjMGvy7UQPa27Oh/Mc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yan Zhai , Kuniyuki Iwashima , Jiri Olsa , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.12 085/154] net: Add rx_skb of kfree_skb to raw_tp_null_args[]. Date: Mon, 24 Feb 2025 15:34:44 +0100 Message-ID: <20250224142610.403646784@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250224142607.058226288@linuxfoundation.org> References: <20250224142607.058226288@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 5da7e15fb5a12e78de974d8908f348e279922ce9 ] Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0] in trace_kfree_skb if the prog does not check if rx_sk is NULL. Commit c53795d48ee8 ("net: add rx_sk to trace_kfree_skb") added rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL. Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier validate such a prog and prevent the issue. Now we fail to load such a prog: libbpf: prog 'drop': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21 0: (79) r3 = *(u64 *)(r1 +24) func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock' 1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1) ; bpf_printk("sk: %d, %d\n", sk, sk->__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24 1: (69) r4 = *(u16 *)(r3 +16) R3 invalid mem access 'trusted_ptr_or_null_' processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 -- END PROG LOAD LOG -- Note this fix requires commit 838a10bd2ebf ("bpf: Augment raw_tp arguments with PTR_MAYBE_NULL"). [0]: BUG: kernel NULL pointer dereference, address: 0000000000000010 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 P4D 0 PREEMPT SMP RIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d Call Trace: ? __die+0x1f/0x60 ? page_fault_oops+0x148/0x420 ? search_bpf_extables+0x5b/0x70 ? fixup_exception+0x27/0x2c0 ? exc_page_fault+0x75/0x170 ? asm_exc_page_fault+0x22/0x30 ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d bpf_trace_run4+0x68/0xd0 ? unix_stream_connect+0x1f4/0x6f0 sk_skb_reason_drop+0x90/0x120 unix_stream_connect+0x1f4/0x6f0 __sys_connect+0x7f/0xb0 __x64_sys_connect+0x14/0x20 do_syscall_64+0x47/0xc30 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Fixes: c53795d48ee8 ("net: add rx_sk to trace_kfree_skb") Reported-by: Yan Zhai Closes: https://lore.kernel.org/netdev/Z50zebTRzI962e6X@debian.debian/ Signed-off-by: Kuniyuki Iwashima Tested-by: Yan Zhai Acked-by: Jiri Olsa Link: https://lore.kernel.org/r/20250201030142.62703-1-kuniyu@amazon.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/btf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index a44f4be592be7..2c54c148a94f3 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6483,6 +6483,8 @@ static const struct bpf_raw_tp_null_args raw_tp_null_args[] = { /* rxrpc */ { "rxrpc_recvdata", 0x1 }, { "rxrpc_resend", 0x10 }, + /* skb */ + {"kfree_skb", 0x1000}, /* sunrpc */ { "xs_stream_read_data", 0x1 }, /* ... from xprt_cong_event event class */ -- 2.39.5