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Message-Id: <20200203161827.768-1-tli@digitalocean.com>
Date: Mon, 3 Feb 2020 10:18:27 -0600
From: Tianlin Li <tli@...italocean.com>
To: kernel-hardening@...ts.openwall.com
Cc: keescook@...omium.org,
Alex Deucher <alexander.deucher@....com>,
christian.koenig@....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,
Tianlin Li <tli@...italocean.com>
Subject: [PATCH v2] drm/radeon: have the callers of set_memory_*() check the return value
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_*().
Signed-off-by: Tianlin Li <tli@...italocean.com>
---
v2:
The hardware is too old to be tested on and the code cannot be simply
removed from the kernel, so this is the solution for the short term.
- Just print an error when something goes wrong
- Remove patch 2.
v1:
https://lore.kernel.org/lkml/20200107192555.20606-1-tli@digitalocean.com/
---
drivers/gpu/drm/radeon/radeon_gart.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c
index f178ba321715..a2cc864aa08d 100644
--- a/drivers/gpu/drm/radeon/radeon_gart.c
+++ b/drivers/gpu/drm/radeon/radeon_gart.c
@@ -80,8 +80,9 @@ int radeon_gart_table_ram_alloc(struct radeon_device *rdev)
#ifdef CONFIG_X86
if (rdev->family == CHIP_RS400 || rdev->family == CHIP_RS480 ||
rdev->family == CHIP_RS690 || rdev->family == CHIP_RS740) {
- set_memory_uc((unsigned long)ptr,
- rdev->gart.table_size >> PAGE_SHIFT);
+ if (set_memory_uc((unsigned long)ptr,
+ rdev->gart.table_size >> PAGE_SHIFT))
+ DRM_ERROR("set_memory_uc failed.\n");
}
#endif
rdev->gart.ptr = ptr;
@@ -106,8 +107,9 @@ void radeon_gart_table_ram_free(struct radeon_device *rdev)
#ifdef CONFIG_X86
if (rdev->family == CHIP_RS400 || rdev->family == CHIP_RS480 ||
rdev->family == CHIP_RS690 || rdev->family == CHIP_RS740) {
- set_memory_wb((unsigned long)rdev->gart.ptr,
- rdev->gart.table_size >> PAGE_SHIFT);
+ if (set_memory_wb((unsigned long)rdev->gart.ptr,
+ rdev->gart.table_size >> PAGE_SHIFT))
+ DRM_ERROR("set_memory_wb failed.\n");
}
#endif
pci_free_consistent(rdev->pdev, rdev->gart.table_size,
--
2.17.1
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