On a 64 bit kernel if an o32 syscall was made with a syscall number less
than 4000, we would read the function from outside of the bounds of the
syscall table. This led to non-deterministic behavior including system
crashes.
While we were at it we reworked the 32 bit version as well to use fewer
instructions. Both 32 and 64 bit versions are use the same code now.
Signed-off-by: Vlad Malov <Vlad.Malov@caviumnetworks.com>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
LEAF(sys_syscall)
subu t0, a0, __NR_O32_Linux # check syscall number
sltiu v0, t0, __NR_O32_Linux_syscalls + 1
LEAF(sys_syscall)
subu t0, a0, __NR_O32_Linux # check syscall number
sltiu v0, t0, __NR_O32_Linux_syscalls + 1
+ beqz t0, einval # do not recurse
sll t1, t0, 3
beqz v0, einval
sll t1, t0, 3
beqz v0, einval
lw t2, sys_call_table(t1) # syscall routine
lw t2, sys_call_table(t1) # syscall routine
- li v1, 4000 - __NR_O32_Linux # index of sys_syscall
- beq t0, v1, einval # do not recurse
-
/* Some syscalls like execve get their arguments from struct pt_regs
and claim zero arguments in the syscall table. Thus we have to
assume the worst case and shuffle around all potential arguments.
/* Some syscalls like execve get their arguments from struct pt_regs
and claim zero arguments in the syscall table. Thus we have to
assume the worst case and shuffle around all potential arguments.
END(handle_sys)
LEAF(sys32_syscall)
END(handle_sys)
LEAF(sys32_syscall)
- sltu v0, a0, __NR_O32_Linux + __NR_O32_Linux_syscalls + 1
+ subu t0, a0, __NR_O32_Linux # check syscall number
+ sltiu v0, t0, __NR_O32_Linux_syscalls + 1
+ beqz t0, einval # do not recurse
+ dsll t1, t0, 3
-
- dsll v0, a0, 3
- ld t2, (sys_call_table - (__NR_O32_Linux * 8))(v0)
-
- li v1, 4000 # indirect syscall number
- beq a0, v1, einval # do not recurse
+ ld t2, sys_call_table(t1) # syscall routine
move a0, a1 # shift argument registers
move a1, a2
move a0, a1 # shift argument registers
move a1, a2