[PATCH v3] drm/radeon: don't include RADEON_HPD_NONE in HPD IRQ enable bitsets

From: Nicolai Stange
Date: Tue Mar 22 2016 - 17:05:41 EST

The values of all but the RADEON_HPD_NONE members of the radeon_hpd_id
enum transform 1:1 into bit positions within the 'enabled' bitset as
assembled by evergreen_hpd_init():

enabled |= 1 << radeon_connector->hpd.hpd;

However, if ->hpd.hpd happens to equal RADEON_HPD_NONE == 0xff, UBSAN
reports

UBSAN: Undefined behaviour in drivers/gpu/drm/radeon/evergreen.c:1867:16
shift exponent 255 is too large for 32-bit type 'int'
[...]
Call Trace:
[<ffffffff818c4d35>] dump_stack+0xbc/0x117
[<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169
[<ffffffff819411bb>] ubsan_epilogue+0xd/0x4e
[<ffffffff81941cbc>] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254
[<ffffffffa0ba7f2e>] ? atom_execute_table+0x3e/0x50 [radeon]
[<ffffffff81941ac1>] ? __ubsan_handle_load_invalid_value+0x158/0x158
[<ffffffffa0b87700>] ? radeon_get_pll_use_mask+0x130/0x130 [radeon]
[<ffffffff81219930>] ? wake_up_klogd_work_func+0x60/0x60
[<ffffffff8121a35e>] ? vprintk_default+0x3e/0x60
[<ffffffffa0c603c4>] evergreen_hpd_init+0x274/0x2d0 [radeon]
[<ffffffffa0c603c4>] ? evergreen_hpd_init+0x274/0x2d0 [radeon]
[<ffffffffa0bd196e>] radeon_modeset_init+0x8ce/0x18d0 [radeon]
[<ffffffffa0b71d86>] radeon_driver_load_kms+0x186/0x350 [radeon]
[<ffffffffa03b6b16>] drm_dev_register+0xc6/0x100 [drm]
[<ffffffffa03bc8c4>] drm_get_pci_dev+0xe4/0x490 [drm]
[<ffffffff814b83f0>] ? kfree+0x220/0x370
[<ffffffffa0b687c2>] radeon_pci_probe+0x112/0x140 [radeon]
[...]
=====================================================================
radeon 0000:01:00.0: No connectors reported connected with modes

At least on x86, there should be no user-visible impact as there

1 << 0xff == 1 << (0xff & 31) == 1 << 31

holds and 31 > RADEON_MAX_HPD_PINS. Thus, this patch is a cosmetic one.

All of the above applies analogously to evergreen_hpd_fini(),
r100_hpd_init(), r100_hpd_fini(), r600_hpd_init(), r600_hpd_fini(),
rs600_hpd_init() and rs600_hpd_fini()

Silence UBSAN by checking ->hpd.hpd for RADEON_HPD_NONE before oring it
into the 'enabled' bitset in the *_init()- or the 'disabled' bitset in
the *_fini()-functions respectively.

Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
---
Applicable to linux-next-20160322.

WARNING: Apart from compilation, the changes to r100.c, r600.c and
rs600.c are untested!

v2 thread can be found here:
http://lkml.kernel.org/g/1458562256-2882-1-git-send-email-nicstange@xxxxxxxxx

Changes to v2:
- Fix the very same issue not only for evergreen, but for r100, r600
and rs600 also.
- Change the commit's subject and description body accordingly.

Changes to v1:
- Turn commit message's impact part into a non-impact part.


drivers/gpu/drm/radeon/evergreen.c | 6 ++++--
drivers/gpu/drm/radeon/r100.c | 6 ++++--
drivers/gpu/drm/radeon/r600.c | 6 ++++--
drivers/gpu/drm/radeon/rs600.c | 6 ++++--
4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 76c4bdf..6360717 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -1864,7 +1864,8 @@ void evergreen_hpd_init(struct radeon_device *rdev)
break;
}
radeon_hpd_set_polarity(rdev, radeon_connector->hpd.hpd);
- enabled |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ enabled |= 1 << radeon_connector->hpd.hpd;
}
radeon_irq_kms_enable_hpd(rdev, enabled);
}
@@ -1907,7 +1908,8 @@ void evergreen_hpd_fini(struct radeon_device *rdev)
default:
break;
}
- disabled |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ disabled |= 1 << radeon_connector->hpd.hpd;
}
radeon_irq_kms_disable_hpd(rdev, disabled);
}
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index 6e478a2..55687f3 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -592,7 +592,8 @@ void r100_hpd_init(struct radeon_device *rdev)

list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
struct radeon_connector *radeon_connector = to_radeon_connector(connector);
- enable |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ enable |= 1 << radeon_connector->hpd.hpd;
radeon_hpd_set_polarity(rdev, radeon_connector->hpd.hpd);
}
radeon_irq_kms_enable_hpd(rdev, enable);
@@ -614,7 +615,8 @@ void r100_hpd_fini(struct radeon_device *rdev)

list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
struct radeon_connector *radeon_connector = to_radeon_connector(connector);
- disable |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ disable |= 1 << radeon_connector->hpd.hpd;
}
radeon_irq_kms_disable_hpd(rdev, disable);
}
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index f86ab69..f4012ae 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -1002,7 +1002,8 @@ void r600_hpd_init(struct radeon_device *rdev)
break;
}
}
- enable |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ enable |= 1 << radeon_connector->hpd.hpd;
radeon_hpd_set_polarity(rdev, radeon_connector->hpd.hpd);
}
radeon_irq_kms_enable_hpd(rdev, enable);
@@ -1055,7 +1056,8 @@ void r600_hpd_fini(struct radeon_device *rdev)
break;
}
}
- disable |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ disable |= 1 << radeon_connector->hpd.hpd;
}
radeon_irq_kms_disable_hpd(rdev, disable);
}
diff --git a/drivers/gpu/drm/radeon/rs600.c b/drivers/gpu/drm/radeon/rs600.c
index 6244f4e..4b35213 100644
--- a/drivers/gpu/drm/radeon/rs600.c
+++ b/drivers/gpu/drm/radeon/rs600.c
@@ -413,7 +413,8 @@ void rs600_hpd_init(struct radeon_device *rdev)
default:
break;
}
- enable |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ enable |= 1 << radeon_connector->hpd.hpd;
radeon_hpd_set_polarity(rdev, radeon_connector->hpd.hpd);
}
radeon_irq_kms_enable_hpd(rdev, enable);
@@ -439,7 +440,8 @@ void rs600_hpd_fini(struct radeon_device *rdev)
default:
break;
}
- disable |= 1 << radeon_connector->hpd.hpd;
+ if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
+ disable |= 1 << radeon_connector->hpd.hpd;
}
radeon_irq_kms_disable_hpd(rdev, disable);
}
--
2.7.4