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| author | Vasily Gorbik <gor@linux.ibm.com> | 2019-06-20 11:18:31 +0300 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2019-07-02 17:00:27 +0300 |
| commit | 20955746320e252b41c6b3505587766012e3e06d (patch) | |
| tree | f7d92a954c4f78f3b44b4fffd36e4cdf003ebc5b | |
| parent | ac6639cd3db607d386616487902b4cc1850a7be5 (diff) | |
| download | linux-20955746320e252b41c6b3505587766012e3e06d.tar.xz | |
s390/kasan: avoid false positives during stack unwind
Avoid kasan false positive when current task is interrupted in-between
stack frame allocation and backchain write instructions leaving new stack
frame backchain invalid. In particular if backchain is 0 the unwinder
tries to read pt_regs from the stack and might hit kasan poisoned bytes,
leading to kasan "stack-out-of-bounds" report.
Disable kasan instrumentation of unwinder stack reads, since this
limitation couldn't be handled otherwise with current backchain unwinder
implementation.
Fixes: 78c98f907413 ("s390/unwind: introduce stack unwind API")
Reported-by: Julian Wiedmann <jwi@linux.ibm.com>
Tested-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | arch/s390/kernel/unwind_bc.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c index 57fd4e902f1f..3ce8a0808059 100644 --- a/arch/s390/kernel/unwind_bc.c +++ b/arch/s390/kernel/unwind_bc.c @@ -46,18 +46,18 @@ bool unwind_next_frame(struct unwind_state *state) regs = state->regs; if (unlikely(regs)) { - sp = READ_ONCE_TASK_STACK(state->task, regs->gprs[15]); + sp = READ_ONCE_NOCHECK(regs->gprs[15]); if (unlikely(outside_of_stack(state, sp))) { if (!update_stack_info(state, sp)) goto out_err; } sf = (struct stack_frame *) sp; - ip = READ_ONCE_TASK_STACK(state->task, sf->gprs[8]); + ip = READ_ONCE_NOCHECK(sf->gprs[8]); reliable = false; regs = NULL; } else { sf = (struct stack_frame *) state->sp; - sp = READ_ONCE_TASK_STACK(state->task, sf->back_chain); + sp = READ_ONCE_NOCHECK(sf->back_chain); if (likely(sp)) { /* Non-zero back-chain points to the previous frame */ if (unlikely(outside_of_stack(state, sp))) { @@ -65,7 +65,7 @@ bool unwind_next_frame(struct unwind_state *state) goto out_err; } sf = (struct stack_frame *) sp; - ip = READ_ONCE_TASK_STACK(state->task, sf->gprs[8]); + ip = READ_ONCE_NOCHECK(sf->gprs[8]); reliable = true; } else { /* No back-chain, look for a pt_regs structure */ @@ -73,9 +73,9 @@ bool unwind_next_frame(struct unwind_state *state) if (!on_stack(info, sp, sizeof(struct pt_regs))) goto out_stop; regs = (struct pt_regs *) sp; - if (user_mode(regs)) + if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE) goto out_stop; - ip = READ_ONCE_TASK_STACK(state->task, regs->psw.addr); + ip = READ_ONCE_NOCHECK(regs->psw.addr); reliable = true; } } @@ -132,11 +132,11 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, /* Get the instruction pointer from pt_regs or the stack frame */ if (regs) { - ip = READ_ONCE_TASK_STACK(state->task, regs->psw.addr); + ip = READ_ONCE_NOCHECK(regs->psw.addr); reliable = true; } else { sf = (struct stack_frame *) sp; - ip = READ_ONCE_TASK_STACK(state->task, sf->gprs[8]); + ip = READ_ONCE_NOCHECK(sf->gprs[8]); reliable = false; } |