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authorMagnus Karlsson <magnus.karlsson@intel.com>2020-04-14 10:35:15 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2020-04-15 14:07:18 +0300
commit99e3a236dd43d06c65af0a2ef9cb44306aef6e02 (patch)
tree14527dbe4aed7324672dfc119739886f523697d0 /net/xdp
parent89f33dcadb349eb926a92633e2c5f61466afc596 (diff)
downloadlinux-99e3a236dd43d06c65af0a2ef9cb44306aef6e02.tar.xz
xsk: Add missing check on user supplied headroom size
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@gmail.com> Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://bugzilla.kernel.org/show_bug.cgi?id=207225 Link: https://lore.kernel.org/bpf/1586849715-23490-1-git-send-email-magnus.karlsson@intel.com
Diffstat (limited to 'net/xdp')
-rw-r--r--net/xdp/xdp_umem.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index fa7bb5e060d0..ed7a6060f73c 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -343,7 +343,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
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 *umem, struct xdp_umem_reg *mr)
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;