Date: Wed, 8 Jan 2020 10:04:54 -0600 From: Tianlin Li <tli@...italocean.com> To: Christian König <christian.koenig@....com> Cc: kernel-hardening@...ts.openwall.com, keescook@...omium.org, 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 > On Jan 8, 2020, at 6:56 AM, Christian König <christian.koenig@....com> wrote: > > 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 */. Thank you. I will fix that in patch 1 and remove patch 2 (since no need to fix the call sites to handle the retval). Best regards, Tianlin > 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(-) Content of type "text/html" skipped
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