mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-09-21 20:22:13 +08:00
riscv: entry: set a0 = -ENOSYS only when syscall != -1
When we test seccomp with 6.4 kernel, we found errno has wrong value. If we deny NETLINK_AUDIT with EAFNOSUPPORT, afterf0bddf5058
, we will get ENOSYS instead. We got same result with commit9c2598d435
("riscv: entry: Save a0 prior syscall_enter_from_user_mode()"). After analysing code, we think that regs->a0 = -ENOSYS should only be executed when syscall != -1. In __seccomp_filter, when seccomp rejected this syscall with specified errno, they will set a0 to return number as syscall ABI, and then return -1. This return number is finally pass as return number of syscall_enter_from_user_mode, and then is compared with NR_syscalls after converted to ulong (so it will be ULONG_MAX). The condition syscall < NR_syscalls will always be false, so regs->a0 = -ENOSYS is always executed. It covered a0 set by seccomp, so we always get ENOSYS when match seccomp RET_ERRNO rule. Fixes:f0bddf5058
("riscv: entry: Convert to generic entry") Reported-by: Felix Yan <felixonmars@archlinux.org> Co-developed-by: Ruizhe Pan <c141028@gmail.com> Signed-off-by: Ruizhe Pan <c141028@gmail.com> Co-developed-by: Shiqi Zhang <shiqi@isrc.iscas.ac.cn> Signed-off-by: Shiqi Zhang <shiqi@isrc.iscas.ac.cn> Signed-off-by: Celeste Liu <CoelacanthusHex@gmail.com> Tested-by: Felix Yan <felixonmars@archlinux.org> Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com> Reviewed-by: Björn Töpel <bjorn@rivosinc.com> Reviewed-by: Guo Ren <guoren@kernel.org> Link: https://lore.kernel.org/r/20230801141607.435192-1-CoelacanthusHex@gmail.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
parent
7e3811521d
commit
52449c17bd
@ -297,7 +297,7 @@ asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
|
|||||||
asmlinkage __visible __trap_section void do_trap_ecall_u(struct pt_regs *regs)
|
asmlinkage __visible __trap_section void do_trap_ecall_u(struct pt_regs *regs)
|
||||||
{
|
{
|
||||||
if (user_mode(regs)) {
|
if (user_mode(regs)) {
|
||||||
ulong syscall = regs->a7;
|
long syscall = regs->a7;
|
||||||
|
|
||||||
regs->epc += 4;
|
regs->epc += 4;
|
||||||
regs->orig_a0 = regs->a0;
|
regs->orig_a0 = regs->a0;
|
||||||
@ -306,9 +306,9 @@ asmlinkage __visible __trap_section void do_trap_ecall_u(struct pt_regs *regs)
|
|||||||
|
|
||||||
syscall = syscall_enter_from_user_mode(regs, syscall);
|
syscall = syscall_enter_from_user_mode(regs, syscall);
|
||||||
|
|
||||||
if (syscall < NR_syscalls)
|
if (syscall >= 0 && syscall < NR_syscalls)
|
||||||
syscall_handler(regs, syscall);
|
syscall_handler(regs, syscall);
|
||||||
else
|
else if (syscall != -1)
|
||||||
regs->a0 = -ENOSYS;
|
regs->a0 = -ENOSYS;
|
||||||
|
|
||||||
syscall_exit_to_user_mode(regs);
|
syscall_exit_to_user_mode(regs);
|
||||||
|
Loading…
Reference in New Issue
Block a user