Date: Wed, 8 Jan 2020 13:56:47 +0100 From: Christian König <christian.koenig@....com> To: Tianlin Li <tli@...italocean.com>, kernel-hardening@...ts.openwall.com, keescook@...omium.org Cc: Alex Deucher <alexander.deucher@....com>, David1.Zhou@....com, David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 0/2] drm/radeon: have the callers of set_memory_*() check the return value Am 07.01.20 um 20:25 schrieb Tianlin Li: > Right now several architectures allow their set_memory_*() family of > functions to fail, but callers may not be checking the return values. > If set_memory_*() returns with an error, call-site assumptions may be > infact wrong to assume that it would either succeed or not succeed at > all. Ideally, the failure of set_memory_*() should be passed up the > call stack, and callers should examine the failure and deal with it. > > Need to fix the callers and add the __must_check attribute. They also > may not provide any level of atomicity, in the sense that the memory > protections may be left incomplete on failure. This issue likely has a > few steps on effects architectures: > 1)Have all callers of set_memory_*() helpers check the return value. > 2)Add __must_check to all set_memory_*() helpers so that new uses do > not ignore the return value. > 3)Add atomicity to the calls so that the memory protections aren't left > in a partial state. > > This series is part of step 1. Make drm/radeon check the return value of > set_memory_*(). I'm a little hesitate merge that. This hardware is >15 years old and nobody of the developers have any system left to test this change on. Would it be to much of a problem to just add something like: r = set_memory_*(); (void)r; /* Intentionally ignored */. Apart from that certainly a good idea to add __must_check to the functions. Regards, Christian. > > Tianlin Li (2): > drm/radeon: have the callers of set_memory_*() check the return value > drm/radeon: change call sites to handle return value properly. > > drivers/gpu/drm/radeon/r100.c | 3 ++- > drivers/gpu/drm/radeon/radeon.h | 2 +- > drivers/gpu/drm/radeon/radeon_gart.c | 22 ++++++++++++++++++---- > drivers/gpu/drm/radeon/rs400.c | 3 ++- > 4 files changed, 23 insertions(+), 7 deletions(-) >
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