The following commit has been merged into the objtool/urgent branch of tip:
Commit-ID: 71c95825289f585014fe9741b051d32a7a916680
Gitweb: https://git.kernel.org/tip/71c95825289f585014fe9741b051d32a7a916680
Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate: Thu, 14 May 2020 15:31:10 -05:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 15 May 2020 10:35:08 +02:00
x86/unwind/orc: Fix error handling in __unwind_start()
The unwind_state 'error' field is used to inform the reliable unwinding
code that the stack trace can't be trusted. Set this field for all
errors in __unwind_start().
Also, move the zeroing out of the unwind_state struct to before the ORC
table initialization check, to prevent the caller from reading
uninitialized data if the ORC table is corrupted.
Fixes: af085d9084b4 ("stacktrace/x86: add function for detecting reliable stack traces")
Fixes: d3a09104018c ("x86/unwinder/orc: Dont bail on stack overflow")
Fixes: 98d0c8ebf77e ("x86/unwind/orc: Prevent unwinding before ORC initialization")
Reported-by: Pavel Machek <pavel@xxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/d6ac7215a84ca92b895fdd2e1aa546729417e6e6.1589487277.git.jpoimboe@xxxxxxxxxx
---
arch/x86/kernel/unwind_orc.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 5b0bd85..fa79e42 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -617,23 +617,23 @@ 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;
+ if (!orc_init)
+ goto err;
+
/*
* Refuse to unwind the stack of a task while it's executing on another
* CPU. This check is racy, but that's ok: the unwinder has other
* checks to prevent it from going off the rails.
*/
if (task_on_another_cpu(task))
- goto done;
+ goto err;
if (regs) {
if (user_mode(regs))
- goto done;
+ goto the_end;
state->ip = regs->ip;
state->sp = regs->sp;
@@ -666,6 +666,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
* generate some kind of backtrace if this happens.
*/
void *next_page = (void *)PAGE_ALIGN((unsigned long)state->sp);
+ state->error = true;
if (get_stack_info(next_page, state->task, &state->stack_info,
&state->stack_mask))
return;
@@ -691,8 +692,9 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
return;
-done:
+err:
+ state->error = true;
+the_end:
state->stack_info.type = STACK_TYPE_UNKNOWN;
- return;
}
EXPORT_SYMBOL_GPL(__unwind_start);
|