On Thu, May 14, 2020 at 10:13:40PM +0200, Pavel Machek wrote:
@@ -563,6 +560,9 @@ EXPORT_SYMBOL_GPL(unwind_next_frame); void __unwind_start(struct unwind_state *state, struct task_struct *task, struct pt_regs *regs, unsigned long *first_frame) {
- if (!orc_init)
goto done;- memset(state, 0, sizeof(*state)); state->task = task;
As this returns the *state to the caller, should the "goto done" move below the memset? Otherwise we are returning partialy-initialized struct, which is ... weird.
Yeah, it is a little weird. In most cases it should be fine, but there is an edge case where if there's a corrupt ORC table and this returns early, 'arch_stack_walk_reliable() -> unwind_error()' could check an uninitialized value.
Also the __unwind_start() error handling needs to set that error bit anyway, in its error cases. I'll fix it up.
I did this in the mean time. It moves goto around memset, and I believe that 8 in get_reg should have been sizeof(long) [not that it matters, x86-32 is protected by build bug on.]
Signed-off-by: Pavel Machek pavel@ucw.cz
I already have the same memset patch (along with other error-handling fixes) which I'll be posting shortly once it runs through my testing.
Since the sizeof(long) thing isn't really a bug, I'll make that change later, along with some other pending improvements I have.