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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-04-25 20:48:51 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-04-26 08:19:05 +0200 |
| commit | b0d50c7b5d807ce6f7ba58e42b260e92bd7d88fb (patch) | |
| tree | e560f9f4127d128d867363a9c3172d27b2694261 /arch/x86 | |
| parent | dc912c303517b01960dcee6875a78b2999f7c098 (diff) | |
| download | linux-b0d50c7b5d807ce6f7ba58e42b260e92bd7d88fb.tar.bz2 | |
x86/unwind: Silence more entry-code related warnings
Borislav Petkov reported the following unwinder warning:
WARNING: kernel stack regs at ffffc9000024fea8 in udevadm:92 has bad 'bp' value 00007fffc4614d30
unwind stack type:0 next_sp: (null) mask:0x6 graph_idx:0
ffffc9000024fea8: 000055a6100e9b38 (0x55a6100e9b38)
ffffc9000024feb0: 000055a6100e9b35 (0x55a6100e9b35)
ffffc9000024feb8: 000055a6100e9f68 (0x55a6100e9f68)
ffffc9000024fec0: 000055a6100e9f50 (0x55a6100e9f50)
ffffc9000024fec8: 00007fffc4614d30 (0x7fffc4614d30)
ffffc9000024fed0: 000055a6100eaf50 (0x55a6100eaf50)
ffffc9000024fed8: 0000000000000000 ...
ffffc9000024fee0: 0000000000000100 (0x100)
ffffc9000024fee8: ffff8801187df488 (0xffff8801187df488)
ffffc9000024fef0: 00007ffffffff000 (0x7ffffffff000)
ffffc9000024fef8: 0000000000000000 ...
ffffc9000024ff10: ffffc9000024fe98 (0xffffc9000024fe98)
ffffc9000024ff18: 00007fffc4614d00 (0x7fffc4614d00)
ffffc9000024ff20: ffffffffffffff10 (0xffffffffffffff10)
ffffc9000024ff28: ffffffff811c6c1f (SyS_newlstat+0xf/0x10)
ffffc9000024ff30: 0000000000000010 (0x10)
ffffc9000024ff38: 0000000000000296 (0x296)
ffffc9000024ff40: ffffc9000024ff50 (0xffffc9000024ff50)
ffffc9000024ff48: 0000000000000018 (0x18)
ffffc9000024ff50: ffffffff816b2e6a (entry_SYSCALL_64_fastpath+0x18/0xa8)
...
It unwinded from an interrupt which came in right after entry code
called into a C syscall handler, before it had a chance to set up the
frame pointer, so regs->bp still had its user space value.
Add a check to silence warnings in such a case, where an interrupt
has occurred and regs->sp is almost at the end of the stack.
Reported-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c32c47c68a0a ("x86/unwind: Warn on bad frame pointer")
Link: http://lkml.kernel.org/r/c695f0d0d4c2cfe6542b90e2d0520e11eb901eb5.1493171120.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/unwind_frame.c | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index bda82df34c7b..ae0821f6c3a5 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -91,16 +91,26 @@ static bool in_entry_code(unsigned long ip) return false; } +static inline unsigned long *last_frame(struct unwind_state *state) +{ + return (unsigned long *)task_pt_regs(state->task) - 2; +} + #ifdef CONFIG_X86_32 #define GCC_REALIGN_WORDS 3 #else #define GCC_REALIGN_WORDS 1 #endif +static inline unsigned long *last_aligned_frame(struct unwind_state *state) +{ + return last_frame(state) - GCC_REALIGN_WORDS; +} + static bool is_last_task_frame(struct unwind_state *state) { - unsigned long *last_bp = (unsigned long *)task_pt_regs(state->task) - 2; - unsigned long *aligned_bp = last_bp - GCC_REALIGN_WORDS; + unsigned long *last_bp = last_frame(state); + unsigned long *aligned_bp = last_aligned_frame(state); /* * We have to check for the last task frame at two different locations @@ -277,10 +287,14 @@ bad_address: /* * Don't warn if the unwinder got lost due to an interrupt in entry - * code before the stack was set up: + * code or in the C handler before the first frame pointer got set up: */ if (state->got_irq && in_entry_code(state->ip)) goto the_end; + if (state->regs && + state->regs->sp >= (unsigned long)last_aligned_frame(state) && + state->regs->sp < (unsigned long)task_pt_regs(state->task)) + goto the_end; if (state->regs) { printk_deferred_once(KERN_WARNING |