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Message-ID: <fc6d2289-af97-5cf8-a4bb-77c2b0b8375c@redhat.com> Date: Mon, 3 Aug 2020 14:17:41 -0400 From: Joe Lawrence <joe.lawrence@...hat.com> To: Kees Cook <keescook@...omium.org>, Evgenii Shatokhin <eshatokhin@...tuozzo.com> Cc: Kristen Carlson Accardi <kristen@...ux.intel.com>, Miroslav Benes <mbenes@...e.cz>, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, arjan@...ux.intel.com, x86@...nel.org, linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com, rick.p.edgecombe@...el.com, live-patching@...r.kernel.org, Josh Poimboeuf <jpoimboe@...hat.com>, Jessica Yu <jeyu@...nel.org>, "Frank Ch. Eigler" <fche@...hat.com> Subject: Re: [PATCH v4 00/10] Function Granular KASLR On 8/3/20 1:45 PM, Kees Cook wrote: > On Mon, Aug 03, 2020 at 02:39:32PM +0300, Evgenii Shatokhin wrote: >> There are at least 2 places where high-order memory allocations might happen >> during module loading. Such allocations may fail if memory is fragmented, >> while physically contiguous memory areas are not really needed there. I >> suggest to switch to kvmalloc/kvfree there. > > While this does seem to be the right solution for the extant problem, I > do want to take a moment and ask if the function sections need to be > exposed at all? What tools use this information, and do they just want > to see the bounds of the code region? (i.e. the start/end of all the > .text* sections) Perhaps .text.* could be excluded from the sysfs > section list? > [[cc += FChE, see [0] for Evgenii's full mail ]] It looks like debugging tools like systemtap [1], gdb [2] and its add-symbol-file cmd, etc. peek at the /sys/module/<MOD>/section/ info. But yeah, it would be preferable if we didn't export a long sysfs representation if nobody actually needs it. [0] https://lore.kernel.org/lkml/e9c4d88b-86db-47e9-4299-3fac45a7e3fd@virtuozzo.com/ [1] https://fossies.org/linux/systemtap/staprun/staprun.c [2] https://www.oreilly.com/library/view/linux-device-drivers/0596005903/ch04.html#linuxdrive3-CHP-4-SECT-6.1 -- Joe
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