This is a note to let you know that I've just added the patch titled
xsk: Add missing check on user supplied headroom size
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xsk-add-missing-check-on-user-supplied-headroom-size.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 Mon Sep 17 00:00:00 2001
From: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
Date: Tue, 14 Apr 2020 09:35:15 +0200
Subject: xsk: Add missing check on user supplied headroom size
From: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
commit 99e3a236dd43d06c65af0a2ef9cb44306aef6e02 upstream.
Add a check that the headroom cannot be larger than the available
space in the chunk. In the current code, a malicious user can set the
headroom to a value larger than the chunk size minus the fixed XDP
headroom. That way packets with a length larger than the supported
size in the umem could get accepted and result in an out-of-bounds
write.
Fixes: c0c77d8fb787 ("xsk: add user memory registration support sockopt")
Reported-by: Bui Quang Minh <minhquangbui99@xxxxxxxxx>
Signed-off-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=207225
Link: https://lore.kernel.org/bpf/1586849715-23490-1-git-send-email-magnus.karlsson@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/xdp/xdp_umem.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -343,7 +343,7 @@ static int xdp_umem_reg(struct xdp_umem
u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
unsigned int chunks, chunks_per_page;
u64 addr = mr->addr, size = mr->len;
- int size_chk, err;
+ int err;
if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
/* Strictly speaking we could support this, if:
@@ -382,8 +382,7 @@ static int xdp_umem_reg(struct xdp_umem
return -EINVAL;
}
- size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM;
- if (size_chk < 0)
+ if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
return -EINVAL;
umem->address = (unsigned long)addr;
Patches currently in stable-queue which might be from magnus.karlsson@xxxxxxxxx are
queue-5.4/xsk-add-missing-check-on-user-supplied-headroom-size.patch
