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Date: Fri, 22 May 2015 09:53:30 -0500 From: Josh Poimboeuf <jpoimboe@...hat.com> To: Andy Lutomirski <luto@...capital.net> Cc: Ingo Molnar <mingo@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>, Peter Zijlstra <peterz@...radead.org>, X86 ML <x86@...nel.org>, live-patching@...r.kernel.org, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Andy Lutomirski <luto@...nel.org>, Denys Vlasenko <dvlasenk@...hat.com>, Brian Gerst <brgerst@...il.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Borislav Petkov <bp@...en8.de>, Andrew Morton <akpm@...ux-foundation.org> Subject: Re: [PATCH v4 0/3] Compile-time stack frame pointer validation On Thu, May 21, 2015 at 02:53:07PM -0700, Andy Lutomirski wrote: > On Thu, May 21, 2015 at 1:54 PM, Josh Poimboeuf <jpoimboe@...hat.com> wrote: > > After removing the frame pointer checks for leaf functions, and adding a > > check for all functions which jump outside of their scope, the number of > > defconfig warnings dropped from 89 -> 47. The Fedora config warning > > count dropped from 207 -> 83. > > > > Here are the remaining 47 warnings for defconfig: > > > > stackvalidate: arch/x86/ia32/ia32entry.o: ia32_sysenter_target() is missing frame pointer logic > > stackvalidate: arch/x86/ia32/ia32entry.o: return instruction outside of a function at .entry.text+0x52e > > stackvalidate: arch/x86/kernel/entry_64.o: return instruction outside of a function at .entry.text+0x359 > > stackvalidate: arch/x86/kernel/entry_64.o: return instruction outside of a function at .entry.text+0x19be > > stackvalidate: arch/x86/kernel/entry_64.o: return instruction outside of a function at .entry.text+0x19e5 > > stackvalidate: arch/x86/kernel/entry_64.o: return instruction outside of a function at .entry.text+0x1c21 > > stackvalidate: arch/x86/kernel/entry_64.o: return instruction outside of a function at .entry.text+0x1ceb > > stackvalidate: arch/x86/kernel/acpi/wakeup_64.o: unsupported jump to outside of the function at wakeup_long64+0x15 > > stackvalidate: arch/x86/kernel/acpi/wakeup_64.o: do_suspend_lowlevel() is missing frame pointer logic > > stackvalidate: arch/x86/kernel/relocate_kernel_64.o: return instruction outside of a function at .text+0x6b > > stackvalidate: arch/x86/kernel/relocate_kernel_64.o: return instruction outside of a function at .text+0xc7 > > stackvalidate: arch/x86/kernel/relocate_kernel_64.o: return instruction outside of a function at .text+0x110 > > stackvalidate: arch/x86/kernel/relocate_kernel_64.o: return instruction outside of a function at .text+0x145 > > stackvalidate: arch/x86/kernel/relocate_kernel_64.o: return instruction outside of a function at .text+0x1c4 > > stackvalidate: arch/x86/kernel/head_64.o: return instruction outside of a function at .head.text+0x1a2 > > stackvalidate: arch/x86/kernel/head_64.o: early_idt_handler() is missing frame pointer logic > > stackvalidate: arch/x86/platform/efi/efi_stub_64.o: efi_call() is missing frame pointer logic > > stackvalidate: arch/x86/realmode/rm/trampoline_64.o: return instruction outside of a function at .text+0x170 > > stackvalidate: arch/x86/realmode/rm/trampoline_64.o: return instruction outside of a function at .text+0x176 > > stackvalidate: arch/x86/realmode/rm/reboot.o: return instruction outside of a function at .text+0x2a > > stackvalidate: arch/x86/realmode/rm/copy.o: copy_from_fs() is missing frame pointer logic > > stackvalidate: arch/x86/realmode/rm/copy.o: copy_to_fs() is missing frame pointer logic > > stackvalidate: arch/x86/power/hibernate_asm_64.o: return instruction outside of a function at .text+0x69 > > stackvalidate: arch/x86/power/hibernate_asm_64.o: return instruction outside of a function at .text+0x16d > > stackvalidate: arch/x86/lib/copy_user_64.o: unsupported jump to outside of the function at _copy_to_user+0x25 > > stackvalidate: arch/x86/lib/copy_user_64.o: unsupported jump to outside of the function at _copy_from_user+0x25 > > stackvalidate: arch/x86/lib/getuser.o: unsupported jump to outside of the function at __get_user_1+0x14 > > stackvalidate: arch/x86/lib/getuser.o: unsupported jump to outside of the function at __get_user_2+0x4 > > stackvalidate: arch/x86/lib/getuser.o: unsupported jump to outside of the function at __get_user_4+0x4 > > stackvalidate: arch/x86/lib/getuser.o: unsupported jump to outside of the function at __get_user_8+0x4 > > stackvalidate: arch/x86/lib/getuser.o: return instruction outside of a function at .text+0xc5 > > stackvalidate: arch/x86/lib/memmove_64.o: return instruction outside of a function at .altinstr_replacement+0x5 > > stackvalidate: arch/x86/lib/putuser.o: unsupported jump to outside of the function at __put_user_1+0x14 > > stackvalidate: arch/x86/lib/putuser.o: unsupported jump to outside of the function at __put_user_2+0x1b > > stackvalidate: arch/x86/lib/putuser.o: unsupported jump to outside of the function at __put_user_4+0x1b > > stackvalidate: arch/x86/lib/putuser.o: unsupported jump to outside of the function at __put_user_8+0x1b > > stackvalidate: arch/x86/lib/putuser.o: return instruction outside of a function at .text+0xc1 > > stackvalidate: arch/x86/lib/rwsem.o: call_rwsem_down_read_failed() is missing frame pointer logic > > stackvalidate: arch/x86/lib/rwsem.o: call_rwsem_down_write_failed() is missing frame pointer logic > > stackvalidate: arch/x86/lib/rwsem.o: call_rwsem_wake() is missing frame pointer logic > > stackvalidate: arch/x86/lib/rwsem.o: call_rwsem_downgrade_wake() is missing frame pointer logic > > stackvalidate: arch/x86/boot/copy.o: copy_from_fs() is missing frame pointer logic > > stackvalidate: arch/x86/boot/copy.o: copy_to_fs() is missing frame pointer logic > > stackvalidate: arch/x86/boot/compressed/head_64.o: return instruction outside of a function at .text+0x16e > > stackvalidate: arch/x86/boot/compressed/head_64.o: return instruction outside of a function at .text+0x172 > > stackvalidate: arch/x86/boot/compressed/head_64.o: startup_32() is missing frame pointer logic > > stackvalidate: arch/x86/boot/pmjump.o: unsupported jump to outside of the function at in_pm32+0x1c > > > > Note that only 13 of the 47 warnings are actually due to missing frame > > pointer logic. The rest are ambiguous conditions which prevent > > stackvalidate from being able to make sense of things: returning from > > outside of a proper ELF function, or jumping from inside of a function > > to outside of its scope. > > > > Similarly, in the Fedora config case, only 27 of the 83 warnings are for > > missing frame pointer logic. > > > > If there are no objections, I'll go with this approach in the next > > version of the patch set. > > I'm willing to review anything with "entry" in its filename. Thanks. I think the "entry" warnings may be false positives, since that code isn't called by any C kernel code. (Now that I'm ignoring leaf functions, the ratio of false positives to true positives has gone up.) The false positives for "return instruction outside of a function" can be marked with the RET_NOVALIDATE macro to tell stackvalidate to ignore the return instruction, or with FILE_NOVALIDATE to tell it to ignore the entire file. I can add some patches to fix the warnings. I'll put you on CC for the "entry" changes. -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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