CVE-2026-93125

Summary

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max

check_kfunc_args() detects a kfunc argument named rdonly_buf_size or rdwr_buf_size and stores reg->var_off.value into meta->r0_size, a u64, and does not bound it. check_kfunc_call() later copies that value into the returned register's mem_size field:

meta->r0_size = reg->var_off.value; … regs[BPF_REG_0].mem_size = meta.r0_size;

regs[BPF_REG_0].mem_size is u32. A constant whose upper 32 bits are set gets truncated instead of causing a load-time rejection, so the verifier records a PTR_TO_MEM register with an approximately 4 GiB mem_size for whatever allocation the kfunc returned. A later access check against that register uses the truncated, wrong bound.

Reject rdonly_buf_size/rdwr_buf_size values that exceed U32_MAX at the point meta->r0_size is set.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/56a3846830ac95a472297d0cbba75cbff29540bb
• https://git.kernel.org/stable/c/2aaf67f0516fde29620d0edfc29c01b9ea7ad430

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