Re: [PATCH v19 00/10] Compile-time stack metadata validation

[Josh Poimboeuf]

On Tue, Mar 08, 2016 at 11:37:16AM +0100, Ingo Molnar wrote:
> 
> * Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> 
> > This is v19 of the compile-time stack metadata validation patch set.
> > 
> > It's based on tip:core/objtool.
> 
> So I've upgraded my main build box to Fedora 23, to:
> 
>   gcc version 5.3.1 20151207 (Red Hat 5.3.1-2) (GCC)
>   GNU assembler version 2.25 (x86_64-redhat-linux) using BFD version version 2.25-15.fc23
>   GNU ld version 2.25-15.fc23
> 
> and I'm now getting a bunch of these warnings:
> 
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2ff: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x30b: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x317: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x323: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x32f: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x33b: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x348: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x355: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x362: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x36f: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x37c: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x389: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x396: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2ff: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x30b: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x317: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x323: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x32f: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x33b: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x348: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x355: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x362: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x36f: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x37c: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x389: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x396: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x19a: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1a6: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1b2: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1be: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1ca: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1d6: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1e2: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1ee: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x1ff: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x210: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x221: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x251: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x262: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x273: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x284: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x295: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2a6: frame pointer state mismatch
> drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2b7: frame pointer state mismatch
> 
> I see nothing particularly weird about rtlwifi_rate_mapping(), except the tons of 
> switch statements - maybe GCC does something really clever here?
> 
> In any case this needs to be addressed before the merge window. Also, I think we 
> should limit the number of objtool warnings to one per function?

This is a bug in objtool's handling of switch statement jump tables.  In
fact, the 0-day bot warned me about this bug yesterday, but I
misinterpreted it:

  https://lkml.kernel.org/r/201603060006.yNZ9xTcs%fengguang.wu@xxxxxxxxx

I'll fix it up today.  I'll also limit the warnings to one per function.

BTW, I was only able to recreate this particular issue after updating to
today's tip/master.  It was triggered by a new config option:
CONFIG_UBSAN_SANITIZE_ALL.

-- 
Josh