On 05/12/2017 10:29 PM, Dmitry Osipenko wrote:
If command buffer claims a number of words that is higher than its BO can
fit and a relocation lays past the BO, a kernel OOPS will be fired on that
relocation address patching. This was triggered by an opentegra Xorg driver
that erroneously pushed too many commands to the pushbuf.
[ 46.829393] Unable to handle kernel paging request at virtual address f09b2000
...
[<c04a3ba4>] (host1x_job_pin) from [<c04dfcd0>] (tegra_drm_submit+0x474/0x510)
[<c04dfcd0>] (tegra_drm_submit) from [<c04deea0>] (tegra_submit+0x50/0x6c)
[<c04deea0>] (tegra_submit) from [<c04c07c0>] (drm_ioctl+0x1e4/0x3ec)
[<c04c07c0>] (drm_ioctl) from [<c02541a0>] (do_vfs_ioctl+0x9c/0x8e4)
[<c02541a0>] (do_vfs_ioctl) from [<c0254a1c>] (SyS_ioctl+0x34/0x5c)
[<c0254a1c>] (SyS_ioctl) from [<c0107640>] (ret_fast_syscall+0x0/0x3c)
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
v2: Take into account the cmdbuf.offset
drivers/gpu/drm/tegra/drm.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 732c8d98044f..9ad4ac7c08d1 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -361,20 +361,30 @@ int tegra_drm_submit(struct tegra_drm_context *context,
while (num_cmdbufs) {
struct drm_tegra_cmdbuf cmdbuf;
- struct host1x_bo *bo;
+ struct drm_gem_object *gem;
+ struct tegra_bo *bo;
if (copy_from_user(&cmdbuf, cmdbufs, sizeof(cmdbuf))) {
err = -EFAULT;
goto fail;
}
- bo = host1x_bo_lookup(file, cmdbuf.handle);
- if (!bo) {
+ gem = drm_gem_object_lookup(file, cmdbuf.handle);
+ if (!gem) {
err = -ENOENT;
goto fail;
}
- host1x_job_add_gather(job, bo, cmdbuf.words, cmdbuf.offset);
+ drm_gem_object_unreference_unlocked(gem);
+
+ if (cmdbuf.offset + cmdbuf.words * 4 > gem->size) {
+ err = -EINVAL;
+ goto fail;
+ }
Nasty bug! Well found. Two points: the arithmetic here could overflow,
so userspace could supply some large values for offset/words and this
check would not catch it. A fix would be to do the arithmetic in 64-bit.
Also, looking at the code closer, I can't see any bounds checking for
relocs either.. That code (host1x_reloc_copy_from_user) is the other
place using host1x_bo_lookup, so we could e.g. change host1x_bo_lookup
to take offset and words parameters and verify those at the same time.
Cheers,
Mikko
+
+ bo = to_tegra_bo(gem);
+ host1x_job_add_gather(job, &bo->base,
+ cmdbuf.words, cmdbuf.offset);
num_cmdbufs--;
cmdbufs++;
}
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