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Yiming QianandGreg Kroah-Hartman
9bb86d8184
commit406e8a651aupstream. The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages. Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache. Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting. Fixes:d3b18ad31f("tls: add bpf support to sk_msg handling") Cc: stable@vger.kernel.org Reported-by: Yiming Qian <yimingqian591@gmail.com> Reported-by: Keenan Dong <keenanat2000@gmail.com> Signed-off-by: Yiming Qian <yimingqian591@gmail.com> Link: https://patch.msgid.link/20260610062137.49075-1-yimingqian591@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>