From: Hou Tao <houtao1@xxxxxxxxxx> Hi, As reported by syzboot [1] and [2], when trying to read vsyscall page by using bpf_probe_read_kernel() or bpf_probe_read(), oops may happen. Thomas Gleixner had proposed a test patch [3], but it seems that no formal patch is posted after about one month [4], so I post it instead and add an Originally-by tag in patch #2. Patch #1 makes is_vsyscall_vaddr() being a common helper. Patch #2 fixes the problem by disallowing vsyscall page read for copy_from_kernel_nofault(). Patch #3 adds one test case to ensure the read of vsyscall page through bpf is rejected. Please see individual patches for more details. Comments are always welcome. [1]: https://lore.kernel.org/bpf/CAG48ez06TZft=ATH1qh2c5mpS5BT8UakwNkzi6nvK5_djC-4Nw@xxxxxxxxxxxxxx/ [2]: https://lore.kernel.org/bpf/CABOYnLynjBoFZOf3Z4BhaZkc5hx_kHfsjiW+UWLoB=w33LvScw@xxxxxxxxxxxxxx/ [3]: https://lore.kernel.org/bpf/87r0jwquhv.ffs@tglx/ [4]: https://lore.kernel.org/bpf/e24b125c-8ff4-9031-6c53-67ff2e01f316@xxxxxxxxxxxxxxx/ Change Log: v2: * move is_vsyscall_vaddr to asm/vsyscall.h instead (Sohil) * elaborate on the reason for disallowing of vsyscall page read in copy_from_kernel_nofault_allowed() (Sohil) * update the commit message of patch #2 to more clearly explain how the oops occurs. (Sohil) * update the commit message of patch #3 to explain the expected return values of various bpf helpers (Yonghong) v1: https://lore.kernel.org/bpf/20240119073019.1528573-1-houtao@xxxxxxxxxxxxxxx/ Hou Tao (3): x86/mm: Move is_vsyscall_vaddr() into asm/vsyscall.h x86/mm: Disallow vsyscall page read for copy_from_kernel_nofault() selftest/bpf: Test the read of vsyscall page under x86-64 arch/x86/include/asm/vsyscall.h | 10 ++++ arch/x86/mm/fault.c | 9 --- arch/x86/mm/maccess.c | 9 +++ .../selftests/bpf/prog_tests/read_vsyscall.c | 57 +++++++++++++++++++ .../selftests/bpf/progs/read_vsyscall.c | 45 +++++++++++++++ 5 files changed, 121 insertions(+), 9 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/read_vsyscall.c create mode 100644 tools/testing/selftests/bpf/progs/read_vsyscall.c -- 2.29.2
