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authorDmitry Monakhov <dmtrmonakhov@yandex-team.ru>2022-04-19 10:34:16 +0300
committerPeter Zijlstra <peterz@infradead.org>2022-04-19 21:58:46 +0200
commit6c8ef58a50b5fab6e364b558143490a2014e2a4f (patch)
tree16b6f224b5a80adfe2a87900e5f554d452f6f4da /arch/x86/kernel
parentf9e14dbbd454581061c736bf70bf5cbb15ac927c (diff)
downloadlinux-6c8ef58a50b5fab6e364b558143490a2014e2a4f.tar.bz2
x86/unwind/orc: Recheck address range after stack info was updated
A crash was observed in the ORC unwinder: BUG: stack guard page was hit at 000000000dd984a2 (stack is 00000000d1caafca..00000000613712f0) kernel stack overflow (page fault): 0000 [#1] SMP NOPTI CPU: 93 PID: 23787 Comm: context_switch1 Not tainted 5.4.145 #1 RIP: 0010:unwind_next_frame Call Trace: <NMI> perf_callchain_kernel get_perf_callchain perf_callchain perf_prepare_sample perf_event_output_forward __perf_event_overflow perf_ibs_handle_irq perf_ibs_nmi_handler nmi_handle default_do_nmi do_nmi end_repeat_nmi This was really two bugs: 1) The perf IBS code passed inconsistent regs to the unwinder. 2) The unwinder didn't handle the bad input gracefully. Fix the latter bug. The ORC unwinder needs to be immune against bad inputs. The problem is that stack_access_ok() doesn't recheck the validity of the full range of registers after switching to the next valid stack with get_stack_info(). Fix that. [ jpoimboe: rewrote commit log ] Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/1650353656-956624-1-git-send-email-dmtrmonakhov@yandex-team.ru Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/unwind_orc.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 794fdef2501a..38185aedf7d1 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -339,11 +339,11 @@ static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
struct stack_info *info = &state->stack_info;
void *addr = (void *)_addr;
- if (!on_stack(info, addr, len) &&
- (get_stack_info(addr, state->task, info, &state->stack_mask)))
- return false;
+ if (on_stack(info, addr, len))
+ return true;
- return true;
+ return !get_stack_info(addr, state->task, info, &state->stack_mask) &&
+ on_stack(info, addr, len);
}
static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,