From: Weiming Shi Date: Mon, 15 Jun 2026 02:19:54 +0000 (+0800) Subject: bpf, sockmap: reject overflowing copy + len in bpf_msg_push_data() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0c0a8ed85349dae298712d79cb276acfeb794d82;p=thirdparty%2Flinux.git bpf, sockmap: reject overflowing copy + len in bpf_msg_push_data() When the scatterlist ring is full or nearly full, bpf_msg_push_data() enters a copy fallback path and computes copy + len for the page allocation size. Since len comes from BPF with arg3_type = ARG_ANYTHING and both are u32, a crafted len can wrap the sum to a small value, causing an undersized allocation followed by an out-of-bounds memcpy. BUG: unable to handle page fault for address: ffffed104089a402 Oops: Oops: 0000 [#1] SMP KASAN NOPTI Call Trace: __asan_memcpy (mm/kasan/shadow.c:105) bpf_msg_push_data (net/core/filter.c:2852 net/core/filter.c:2788) bpf_prog_9ed8b5711920a7d7+0x2e/0x36 sk_psock_msg_verdict (net/core/skmsg.c:934) tcp_bpf_sendmsg (net/ipv4/tcp_bpf.c:421 net/ipv4/tcp_bpf.c:584) __sys_sendto (net/socket.c:2206) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Add an overflow check before the allocation. Link: https://lore.kernel.org/all/20260424155913.A19FDC19425@smtp.kernel.org Fixes: 6fff607e2f14 ("bpf: sk_msg program helper bpf_msg_push_data") Tested-by: Xiang Mei Tested-by: Xinyu Ma Reviewed-by: Jiayuan Chen Reviewed-by: Emil Tsalapatis Reviewed-by: Kuniyuki Iwashima Signed-off-by: Weiming Shi Signed-off-by: Jiayuan Chen Link: https://lore.kernel.org/r/20260615021959.140010-2-jiayuan.chen@linux.dev Signed-off-by: Alexei Starovoitov --- diff --git a/net/core/filter.c b/net/core/filter.c index 57b00c6cc8cc..4b159045881d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2829,6 +2829,9 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start, if (!space || (space == 1 && start != offset)) copy = msg->sg.data[i].length; + if (unlikely(copy + len < copy)) + return -EINVAL; + page = alloc_pages(__GFP_NOWARN | GFP_ATOMIC | __GFP_COMP, get_order(copy + len)); if (unlikely(!page))