From: YunJe Shin <yjshin0438@gmail.com> stable inclusion from stable-v6.6.128 commit a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/13865 CVE: CVE-2026-23243 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 5551b02fdbfd85a325bb857f3a8f9c9f33397ed2 upstream. ib_umad_write computes data_len from user-controlled count and the MAD header sizes. With a mismatched user MAD header size and RMPP header length, data_len can become negative and reach ib_create_send_mad(). This can make the padding calculation exceed the segment size and trigger an out-of-bounds memset in alloc_send_rmpp_list(). Add an explicit check to reject negative data_len before creating the send buffer. KASAN splat: [ 211.363464] BUG: KASAN: slab-out-of-bounds in ib_create_send_mad+0xa01/0x11b0 [ 211.364077] Write of size 220 at addr ffff88800c3fa1f8 by task spray_thread/102 [ 211.365867] ib_create_send_mad+0xa01/0x11b0 [ 211.365887] ib_umad_write+0x853/0x1c80 Fixes: 2be8e3ee8efd ("IB/umad: Add P_Key index support") Signed-off-by: YunJe Shin <ioerts@kookmin.ac.kr> Link: https://patch.msgid.link/20260203100628.1215408-1-ioerts@kookmin.ac.kr Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Liu Kai <liukai284@huawei.com> --- drivers/infiniband/core/user_mad.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 2ed749f50a29..285f251fc014 100644 --- a/drivers/infiniband/core/user_mad.c +++ b/drivers/infiniband/core/user_mad.c @@ -514,7 +514,8 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf, struct rdma_ah_attr ah_attr; struct ib_ah *ah; __be64 *tid; - int ret, data_len, hdr_len, copy_offset, rmpp_active; + int ret, hdr_len, copy_offset, rmpp_active; + size_t data_len; u8 base_version; if (count < hdr_size(file) + IB_MGMT_RMPP_HDR) @@ -588,7 +589,10 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf, } base_version = ((struct ib_mad_hdr *)&packet->mad.data)->base_version; - data_len = count - hdr_size(file) - hdr_len; + if (check_sub_overflow(count, hdr_size(file) + hdr_len, &data_len)) { + ret = -EINVAL; + goto err_ah; + } packet->msg = ib_create_send_mad(agent, be32_to_cpu(packet->mad.hdr.qpn), packet->mad.hdr.pkey_index, rmpp_active, -- 2.34.1