CVE-2022-48744
net/mlx5e: Avoid field-overflowing memcpy()
At a glance
- Severity
- HIGH 7.5
- EPSS
- EPSS 0.60 % · percentile 49 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Linux
- NVD status
- Modified
Description
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Avoid field-overflowing memcpy()
In preparation for FORTIFY_SOURCE 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 ETH_HLEN 14
#define VLAN_HLEN 4
...
#define MLX5E_XDP_MIN_INLINE (ETH_HLEN + VLAN_HLEN)
...
struct mlx5e_tx_wqe *wqe = mlx5_wq_cyc_get_wqe(wq, pi);
...
struct mlx5_wqe_eth_seg *eseg = &wqe->eth;
struct mlx5_wqe_data_seg *dseg = wqe->data;
...
memcpy(eseg->inline_hdr.start, xdptxd->data, MLX5E_XDP_MIN_INLINE);
target is wqe->eth.inline_hdr.start (which the compiler sees as being
2 bytes in size), but copying 18, intending to write across start
(really vlan_tci, 2 bytes). The remaining 16 bytes get written into
wqe->data[0], covering byte_count (4 bytes), lkey (4 bytes), and addr
(8 bytes).
struct mlx5e_tx_wqe {
struct mlx5_wqe_ctrl_seg ctrl; /* 0 16 */
struct mlx5_wqe_eth_seg eth; /* 16 16 */
struct mlx5_wqe_data_seg data[]; /* 32 0 */
/* size: 32, cachelines: 1, members: 3 */
/* last cacheline: 32 bytes */
};
struct mlx5_wqe_eth_seg {
u8 swp_outer_l4_offset; /* 0 1 */
u8 swp_outer_l3_offset; /* 1 1 */
u8 swp_inner_l4_offset; /* 2 1 */
u8 swp_inner_l3_offset; /* 3 1 */
u8 cs_flags; /* 4 1 */
u8 swp_flags; /* 5 1 */
__be16 mss; /* 6 2 */
__be32 flow_table_metadata; /* 8 4 */
union {
struct {
__be16 sz; /* 12 2 */
u8 start[2]; /* 14 2 */
} inline_hdr; /* 12 4 */
struct {
__be16 type; /* 12 2 */
__be16 vlan_tci; /* 14 2 */
} insert; /* 12 4 */
__be32 trailer; /* 12 4 */
}; /* 12 4 */
/* size: 16, cachelines: 1, members: 9 */
/* last cacheline: 16 bytes */
};
struct mlx5_wqe_data_seg {
__be32 byte_count; /* 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 mlx5e_tx_wqe
nor struct mlx5e_umr_wqe. "objdump -d" shows no meaningful object
code changes (i.e. only source line number induced differences and
optimizations).
Scores
| Version | Score | Vector | Scored by |
|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | Linux |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary) |
| CVSS 3.1 | HIGH 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD · nvd@nist.gov (Primary) |
Weaknesses (CWE)
European references
CERT-FR advisories
Affected configurations (NVD CPE)
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* ≥ 4.9 < 5.10.248cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* ≥ 5.11 < 5.16.6cpe:2.3:o:linux:linux_kernel:5.17:rc1:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:5.17:rc2:*:*:*:*:*:*
Affected products
| Product | Versions |
|---|
| Linux · Linux | affected b5503b994ed5ed8dbfe821317e7b5b38acb065c5 < 49bcbe531f79fc35bb10020f7695f9f01e4f0ca8 ; affected b5503b994ed5ed8dbfe821317e7b5b38acb065c5 < 8fbdf8c8b8ab82beab882175157650452c46493e ; affected b5503b994ed5ed8dbfe821317e7b5b38acb065c5 < ad5185735f7dab342fdd0dd41044da4c9ccfef67 |
| Linux · Linux | affected 4.9 ; unaffected 0 < 4.9 ; unaffected 5.10.248 ≤ 5.10.* ; unaffected 5.16.6 ≤ 5.16.* ; unaffected 5.17 ≤ * |
References
Sources
