| Message ID | 20191218084757.904971-1-david.abdurachmanov@sifive.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv: reject invalid syscalls below -1 | expand |
On Dez 18 2019, David Abdurachmanov wrote: > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > index a1349ca64669..e163b7b64c86 100644 > --- a/arch/riscv/kernel/entry.S > +++ b/arch/riscv/kernel/entry.S > @@ -246,6 +246,7 @@ check_syscall_nr: > */ > li t1, -1 > beq a7, t1, ret_from_syscall_rejected > + blt a7, t1, 1f How about using bgeu instead in the preceding check? /* * Syscall number held in a7. * If syscall number is above allowed value, redirect to ni_syscall. */ bge a7, t0, 1f Andreas.
On Wed, Dec 18, 2019 at 11:46 AM Andreas Schwab <schwab@suse.de> wrote: > > On Dez 18 2019, David Abdurachmanov wrote: > > > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > > index a1349ca64669..e163b7b64c86 100644 > > --- a/arch/riscv/kernel/entry.S > > +++ b/arch/riscv/kernel/entry.S > > @@ -246,6 +246,7 @@ check_syscall_nr: > > */ > > li t1, -1 > > beq a7, t1, ret_from_syscall_rejected > > + blt a7, t1, 1f > > How about using bgeu instead in the preceding check? The syscall number could be -1 if tracer rejected it. We could do: li t0, __NR_syscalls [..] // first check if syscall was rejected li t1, -1 beq a7, t1, ret_from_syscall_rejected // then check the bounds bgeu a7, t0, 1f > > /* > * Syscall number held in a7. > * If syscall number is above allowed value, redirect to ni_syscall. > */ > bge a7, t0, 1f > > Andreas. > > -- > Andreas Schwab, SUSE Labs, schwab@suse.de > GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 > "And now for something completely different."
On Dez 18 2019, David Abdurachmanov wrote: > On Wed, Dec 18, 2019 at 11:46 AM Andreas Schwab <schwab@suse.de> wrote: >> >> On Dez 18 2019, David Abdurachmanov wrote: >> >> > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S >> > index a1349ca64669..e163b7b64c86 100644 >> > --- a/arch/riscv/kernel/entry.S >> > +++ b/arch/riscv/kernel/entry.S >> > @@ -246,6 +246,7 @@ check_syscall_nr: >> > */ >> > li t1, -1 >> > beq a7, t1, ret_from_syscall_rejected >> > + blt a7, t1, 1f >> >> How about using bgeu instead in the preceding check? > > The syscall number could be -1 if tracer rejected it. So check for -1 first, then for out-of-range? Andreas.
On Wed, 18 Dec 2019, David Abdurachmanov wrote: > Running "stress-ng --enosys 4 -t 20 -v" showed a large number of kernel oops > with "Unable to handle kernel paging request at virtual address" message. This > happens when enosys stressor starts testing random non-valid syscalls. > > I forgot to redirect any syscall below -1 to sys_ni_syscall. > > With the patch kernel oops messages are gone while running stress-ng enosys > stressor. > > Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com> > Fixes: 5340627e3fe0 ("riscv: add support for SECCOMP and SECCOMP_FILTER") From the thread, I couldn't tell whether you were happy with this patch as it stands or not; the thread seems to have petered out. So this one has been queued for v5.5-rc; let me know if you didn't intend for that to happen. - Paul
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index a1349ca64669..e163b7b64c86 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -246,6 +246,7 @@ check_syscall_nr: */ li t1, -1 beq a7, t1, ret_from_syscall_rejected + blt a7, t1, 1f /* Call syscall */ la s0, sys_call_table slli t0, a7, RISCV_LGPTR
Running "stress-ng --enosys 4 -t 20 -v" showed a large number of kernel oops with "Unable to handle kernel paging request at virtual address" message. This happens when enosys stressor starts testing random non-valid syscalls. I forgot to redirect any syscall below -1 to sys_ni_syscall. With the patch kernel oops messages are gone while running stress-ng enosys stressor. Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com> Fixes: 5340627e3fe0 ("riscv: add support for SECCOMP and SECCOMP_FILTER") --- arch/riscv/kernel/entry.S | 1 + 1 file changed, 1 insertion(+)