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 389AB9446 for ; Sun, 13 Aug 2023 21:44:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4283C433C8; Sun, 13 Aug 2023 21:44:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691963074; bh=6rvGpatzJf0x/s1jkzkVD7adM8Q2VX3kXAf2tvDGYyU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X906zFFKCjV+V5dGsaxCpLfefNEXA+zVaksJnNl5mAPmE797jNn5oVaZiaeD+PVDJ q8FY8H/6H7+PeerC59NHoIqb/6c1O0OEe6KMehP6UJttJxQBQyNeoDpJHKtWsEfo2c 7+XqVvIP7RX+4UCi84/NQLULRGslYpvqI+15G2Zs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Kanner , Jesper Dangaard Brouer , Jason Wang , Jakub Kicinski , syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com Subject: [PATCH 5.15 43/89] net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail() Date: Sun, 13 Aug 2023 23:19:34 +0200 Message-ID: <20230813211712.086724297@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230813211710.787645394@linuxfoundation.org> References: <20230813211710.787645394@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Andrew Kanner commit d14eea09edf427fa36bd446f4a3271f99164202f upstream. Syzkaller reported the following issue: ======================================= Too BIG xdp->frame_sz = 131072 WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121 ____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline] WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121 bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103 ... Call Trace: bpf_prog_4add87e5301a4105+0x1a/0x1c __bpf_prog_run include/linux/filter.h:600 [inline] bpf_prog_run_xdp include/linux/filter.h:775 [inline] bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721 netif_receive_generic_xdp net/core/dev.c:4807 [inline] do_xdp_generic+0x35c/0x770 net/core/dev.c:4866 tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919 tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043 call_write_iter include/linux/fs.h:1871 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x650/0xe40 fs/read_write.c:584 ksys_write+0x12f/0x250 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87 ("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper Dangaard Brouer noted that after introducing the xdp_init_buff() which all XDP driver use - it's safe to remove this check. The original intend was to catch cases where XDP drivers have not been updated to use xdp.frame_sz, but that is not longer a concern (since xdp_init_buff). Running the initial syzkaller repro it was discovered that the contiguous physical memory allocation is used for both xdp paths in tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also stated by Jesper Dangaard Brouer that XDP can work on higher order pages, as long as this is contiguous physical memory (e.g. a page). Reported-and-tested-by: syzbot+f817490f5bd20541b90a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000774b9205f1d8a80d@google.com/T/ Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a Link: https://lore.kernel.org/all/20230725155403.796-1-andrew.kanner@gmail.com/T/ Fixes: 43b5169d8355 ("net, xdp: Introduce xdp_init_buff utility routine") Signed-off-by: Andrew Kanner Acked-by: Jesper Dangaard Brouer Acked-by: Jason Wang Link: https://lore.kernel.org/r/20230803190316.2380231-1-andrew.kanner@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/core/filter.c | 6 ------ 1 file changed, 6 deletions(-) --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3843,12 +3843,6 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct x if (unlikely(data_end > data_hard_end)) return -EINVAL; - /* ALL drivers MUST init xdp->frame_sz, chicken check below */ - if (unlikely(xdp->frame_sz > PAGE_SIZE)) { - WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz); - return -EINVAL; - } - if (unlikely(data_end < xdp->data + ETH_HLEN)) return -EINVAL;