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| author |   Josh Poimboeuf <jpoimboe@redhat.com> | 2020-05-14 15:31:10 -0500 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2020-05-15 10:35:08 +0200 |
| commit | 71c95825289f585014fe9741b051d32a7a916680 (patch) | |
| tree | b2bd84791c9e99317e70244bdcb6da2bd1e51465 /arch | |
| parent | Linux 5.7-rc5 (diff) | |
| download | linux-dev-71c95825289f585014fe9741b051d32a7a916680.tar.xz linux-dev-71c95825289f585014fe9741b051d32a7a916680.zip | |
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@denx.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/d6ac7215a84ca92b895fdd2e1aa546729417e6e6.1589487277.git.jpoimboe@redhat.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/unwind_orc.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index 5b0bd8581fe6..fa79e4227d3d 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); |