Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix memory access flags in helper prototypes After commit 37cce22dbd51 ("bpf: verifier: Refactor helper access type tracking"), the verifier started relying on the access type flags in helper function prototypes to perform memory access optimizations. Currently, several helper functions utilizing ARG_PTR_TO_MEM lack the corresponding MEM_RDONLY or MEM_WRITE flags. This omission causes the verifier to incorrectly assume that the buffer contents are unchanged across the helper call. Consequently, the verifier may optimize away subsequent reads based on this wrong assumption, leading to correctness issues. For bpf_get_stack_proto_raw_tp, the original MEM_RDONLY was incorrect since the helper writes to the buffer. Change it to ARG_PTR_TO_UNINIT_MEM which correctly indicates write access to potentially uninitialized memory. Similar issues were recently addressed for specific helpers in commit ac44dcc788b9 ("bpf: Fix verifier assumptions of bpf_d_path's output buffer") and commit 2eb7648558a7 ("bpf: Specify access type of bpf_sysctl_get_name args"). Fix these prototypes by adding the correct memory access flags.

References 3

• git.kernel.org https://git.kernel.org/stable/c/802eef5afb1865bc5536a5302c068ba2215a1f72
• git.kernel.org https://git.kernel.org/stable/c/aa319592892068bd960c1a1c07bd621085b0c63d
• git.kernel.org https://git.kernel.org/stable/c/fdfe75161f6e8c41a7d3023fbb815b537107b806

Remediation