From b383d4ea272fe5795877506dcce5aad1f6330e5e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 25 Jan 2024 10:33:17 +0000 Subject: [PATCH] tcp: add sanity checks to rx zerocopy [ Upstream commit 577e4432f3ac810049cb7e6b71f4d96ec7c6e894 ] TCP rx zerocopy intent is to map pages initially allocated from NIC drivers, not pages owned by a fs. This patch adds to can_map_frag() these additional checks: - Page must not be a compound one. - page->mapping must be NULL. This fixes the panic reported by ZhangPeng. syzbot was able to loopback packets built with sendfile(), mapping pages owned by an ext4 file to TCP rx zerocopy. r3 = socket$inet_tcp(0x2, 0x1, 0x0) mmap(&(0x7f0000ff9000/0x4000)=nil, 0x4000, 0x0, 0x12, r3, 0x0) r4 = socket$inet_tcp(0x2, 0x1, 0x0) bind$inet(r4, &(0x7f0000000000)={0x2, 0x4e24, @multicast1}, 0x10) connect$inet(r4, &(0x7f00000006c0)={0x2, 0x4e24, @empty}, 0x10) r5 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00', 0x181e42, 0x0) fallocate(r5, 0x0, 0x0, 0x85b8) sendfile(r4, r5, 0x0, 0x8ba0) getsockopt$inet_tcp_TCP_ZEROCOPY_RECEIVE(r4, 0x6, 0x23, &(0x7f00000001c0)={&(0x7f0000ffb000/0x3000)=nil, 0x3000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, &(0x7f0000000440)=0x40) r6 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00', 0x181e42, 0x0) Fixes: 93ab6cc69162 ("tcp: implement mmap() for zero copy receive") Link: https://lore.kernel.org/netdev/5106a58e-04da-372a-b836-9d3d0bd2507b@huawei.com/T/ Reported-and-bisected-by: ZhangPeng Signed-off-by: Eric Dumazet Cc: Arjun Roy Cc: Matthew Wilcox Cc: linux-mm@vger.kernel.org Cc: Andrew Morton Cc: linux-fsdevel@vger.kernel.org Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/tcp.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 90e24c3f6557..86e7695d91ad 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1934,7 +1934,17 @@ static skb_frag_t *skb_advance_to_frag(struct sk_buff *skb, u32 offset_skb, static bool can_map_frag(const skb_frag_t *frag) { - return skb_frag_size(frag) == PAGE_SIZE && !skb_frag_off(frag); + struct page *page; + + if (skb_frag_size(frag) != PAGE_SIZE || skb_frag_off(frag)) + return false; + + page = skb_frag_page(frag); + + if (PageCompound(page) || page->mapping) + return false; + + return true; } static int find_next_mappable_frag(const skb_frag_t *frag,