diff options
| author | Celeste Liu <[email protected]> | 2024-06-27 22:23:39 +0800 |
|---|---|---|
| committer | Palmer Dabbelt <[email protected]> | 2024-08-14 13:12:22 -0700 |
| commit | 61119394631f219e23ce98bcc3eb993a64a8ea64 (patch) | |
| tree | b0b47a1e641edcb5eff2b050813872501dc5b8c9 | |
| parent | ee9a68394b4bea8b9044ec4bfdbaacf45297ecef (diff) | |
riscv: entry: always initialize regs->a0 to -ENOSYS
Otherwise when the tracer changes syscall number to -1, the kernel fails
to initialize a0 with -ENOSYS and subsequently fails to return the error
code of the failed syscall to userspace. For example, it will break
strace syscall tampering.
Fixes: 52449c17bdd1 ("riscv: entry: set a0 = -ENOSYS only when syscall != -1")
Reported-by: "Dmitry V. Levin" <[email protected]>
Reviewed-by: Björn Töpel <[email protected]>
Cc: [email protected]
Signed-off-by: Celeste Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>
| -rw-r--r-- | arch/riscv/kernel/traps.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 05a16b1f0aee..51ebfd23e007 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -319,6 +319,7 @@ void do_trap_ecall_u(struct pt_regs *regs) regs->epc += 4; regs->orig_a0 = regs->a0; + regs->a0 = -ENOSYS; riscv_v_vstate_discard(regs); @@ -328,8 +329,7 @@ void do_trap_ecall_u(struct pt_regs *regs) if (syscall >= 0 && syscall < NR_syscalls) syscall_handler(regs, syscall); - else if (syscall != -1) - regs->a0 = -ENOSYS; + /* * Ultimately, this value will get limited by KSTACK_OFFSET_MAX(), * so the maximum stack offset is 1k bytes (10 bits). |