5.4-stable review patch. If anyone has any objections, please let me know.
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From: Nathan Chancellor nathan@kernel.org
commit adf53771a3123df99ca26e38818760fbcf5c05d0 upstream.
When building with CONFIG_FORTIFY_SOURCE=y and W=1, there is a warning because of the memcpy() in syscall_get_arguments():
In file included from include/linux/string.h:392, from include/linux/bitmap.h:13, from include/linux/cpumask.h:12, from arch/riscv/include/asm/processor.h:55, from include/linux/sched.h:13, from kernel/ptrace.c:13: In function 'fortify_memcpy_chk', inlined from 'syscall_get_arguments.isra' at arch/riscv/include/asm/syscall.h:66:2: include/linux/fortify-string.h:580:25: error: call to '__read_overflow2_field' declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning] 580 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors
The fortified memcpy() routine enforces that the source is not overread and the destination is not overwritten if the size of either field and the size of the copy are known at compile time. The memcpy() in syscall_get_arguments() intentionally overreads from a1 to a5 in 'struct pt_regs' but this is bigger than the size of a1.
Normally, this could be solved by wrapping a1 through a5 with struct_group() but there was already a struct_group() applied to these members in commit bba547810c66 ("riscv: tracing: Fix __write_overflow_field in ftrace_partial_regs()").
Just avoid memcpy() altogether and write the copying of args from regs manually, which clears up the warning at the expense of three extra lines of code.
Signed-off-by: Nathan Chancellor nathan@kernel.org Reviewed-by: Dmitry V. Levin ldv@strace.io Fixes: e2c0cdfba7f6 ("RISC-V: User-facing API") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250409-riscv-avoid-fortify-warning-syscall_get_a... Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/riscv/include/asm/syscall.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -67,8 +67,11 @@ static inline void syscall_get_arguments unsigned long *args) { args[0] = regs->orig_a0; - args++; - memcpy(args, ®s->a1, 5 * sizeof(args[0])); + args[1] = regs->a1; + args[2] = regs->a2; + args[3] = regs->a3; + args[4] = regs->a4; + args[5] = regs->a5; }
static inline void syscall_set_arguments(struct task_struct *task,