DEBIAN-CVE-2022-48744

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Avoid field-overflowing memcpy() In preparation for FORTIFYSOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally writing across neighboring fields. Use flexible arrays instead of zero-element arrays (which look like they are always overflowing) and split the cross-field memcpy() into two halves that can be appropriately bounds-checked by the compiler. We were doing: #define ETHHLEN 14 #define VLANHLEN 4 ... #define MLX5EXDPMININLINE (ETHHLEN + VLANHLEN) ... struct mlx5etxwqe *wqe = mlx5wqcycgetwqe(wq, pi); ... struct mlx5wqeethseg *eseg = &wqe->eth; struct mlx5wqedataseg dseg = wqe->data; ... memcpy(eseg->inlinehdr.start, xdptxd->data, MLX5EXDPMININLINE); target is wqe->eth.inlinehdr.start (which the compiler sees as being 2 bytes in size), but copying 18, intending to write across start (really vlantci, 2 bytes). The remaining 16 bytes get written into wqe->data[0], covering bytecount (4 bytes), lkey (4 bytes), and addr (8 bytes). struct mlx5etxwqe { struct mlx5wqectrlseg ctrl; / 0 16 */ struct mlx5wqeethseg eth; /* 16 16 */ struct mlx5wqedataseg data[]; /* 32 0 / / size: 32, cachelines: 1, members: 3 / / last cacheline: 32 bytes / }; struct mlx5wqeethseg { u8 swpouterl4offset; / 0 1 */ u8 swpouterl3offset; /* 1 1 */ u8 swpinnerl4offset; /* 2 1 */ u8 swpinnerl3offset; /* 3 1 */ u8 csflags; /* 4 1 / u8 swp_flags; / 5 1 / __be16 mss; / 6 2 / __be32 flowtablemetadata; / 8 4 / union { struct { __be16 sz; / 12 2 / u8 start[2]; / 14 2 / } inline_hdr; / 12 4 / struct { __be16 type; / 12 2 / _be16 vlantci; / 14 2 / } insert; / 12 4 / __be32 trailer; / 12 4 / }; / 12 4 / / size: 16, cachelines: 1, members: 9 / / last cacheline: 16 bytes */ }; struct mlx5wqedataseg { be32 bytecount; /* 0 4 / __be32 lkey; / 4 4 / __be64 addr; / 8 8 / / size: 16, cachelines: 1, members: 3 / / last cacheline: 16 bytes */ }; So, split the memcpy() so the compiler can reason about the buffer sizes. "pahole" shows no size nor member offset changes to struct mlx5etxwqe nor struct mlx5eumrwqe. "objdump -d" shows no meaningful object code changes (i.e. only source line number induced differences and optimizations).