5.10-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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.c... Reported-and-bisected-by: ZhangPeng zhangpeng362@huawei.com Signed-off-by: Eric Dumazet edumazet@google.com Cc: Arjun Roy arjunroy@google.com Cc: Matthew Wilcox willy@infradead.org Cc: linux-mm@vger.kernel.org Cc: Andrew Morton akpm@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 18541527abce..a5c15e2d193f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1780,7 +1780,17 @@ 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,