[PW_SID:1101476] [net] 6lowpan: fix off-by-one in multicast context address compression#249
[PW_SID:1101476] [net] 6lowpan: fix off-by-one in multicast context address compression#249BluezTestBot wants to merge 1 commit into
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The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses &data[1] as destination and &ipaddr->s6_addr[11] as source, but both should be offset by one: &data[2] and &ipaddr->s6_addr[12] respectively. This off-by-one has two consequences: 1. data[1] is overwritten with s6_addr[11], corrupting the RIID field in the compressed multicast address 2. data[5] is never written, so uninitialized kernel stack memory is transmitted over the network via lowpan_push_hc_data(), leaking kernel stack contents The correct inline data layout must match what the decompression function lowpan_uncompress_multicast_ctx_daddr() expects: data[0..1] = s6_addr[1..2] (flags/scope + RIID) data[2..5] = s6_addr[12..15] (group ID) Also zero-initialize the data array as a defensive measure against similar bugs in the future. Fixes: 5609c18 ("6lowpan: iphc: add support for stateful compression") Reported-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn> Reported-by: Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn> Reported-by: Ao Wang <wangao@seu.edu.cn> Reported-by: Xuewei Feng <fengxw06@126.com> Reported-by: Qi Li <qli01@tsinghua.edu.cn> Reported-by: Ke Xu <xuke@tsinghua.edu.cn> Assisted-by: GLM:GLM-5.1 Signed-off-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>
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2 participants
The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses
&data[1] as destination and &ipaddr->s6_addr[11] as source, but
both should be offset by one: &data[2] and &ipaddr->s6_addr[12]
respectively.
This off-by-one has two consequences:
field in the compressed multicast address
is transmitted over the network via lowpan_push_hc_data(),
leaking kernel stack contents
The correct inline data layout must match what the decompression
function lowpan_uncompress_multicast_ctx_daddr() expects:
data[0..1] = s6_addr[1..2] (flags/scope + RIID)
data[2..5] = s6_addr[12..15] (group ID)
Also zero-initialize the data array as a defensive measure against
similar bugs in the future.
Fixes: 5609c18 ("6lowpan: iphc: add support for stateful compression")
Reported-by: Yizhou Zhao zhaoyz24@mails.tsinghua.edu.cn
Reported-by: Yuxiang Yang yangyx22@mails.tsinghua.edu.cn
Reported-by: Ao Wang wangao@seu.edu.cn
Reported-by: Xuewei Feng fengxw06@126.com
Reported-by: Qi Li qli01@tsinghua.edu.cn
Reported-by: Ke Xu xuke@tsinghua.edu.cn
Assisted-by: GLM:GLM-5.1
Signed-off-by: Yizhou Zhao zhaoyz24@mails.tsinghua.edu.cn
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