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drm: remove redundant code form drm_ioc32.c
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The compat ioctl handler ends up calling access_ok() twice: first
indirectly inside compat_alloc_user_space() and then after returning
from that function. This patch fixes issue.

v2: there were three invalid removals of access_ok() that I've fixed.
Also went through all the changes couple of times and verified that
access_ok() is only removed when the buffer is allocated with
compat_alloc_user_space(). My deepest apologies for this kind of
sloppiness!

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Jarkko Sakkinen authored and Daniel Vetter committed Jul 3, 2015
1 parent e4f31ad commit 1f96bee
Showing 1 changed file with 26 additions and 29 deletions.
55 changes: 26 additions & 29 deletions drivers/gpu/drm/drm_ioc32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ static int compat_drm_version(struct file *file, unsigned int cmd,
return -EFAULT;

version = compat_alloc_user_space(sizeof(*version));
if (!access_ok(VERIFY_WRITE, version, sizeof(*version)))
if (!version)
return -EFAULT;
if (__put_user(v32.name_len, &version->name_len)
|| __put_user((void __user *)(unsigned long)v32.name,
Expand Down Expand Up @@ -140,7 +140,7 @@ static int compat_drm_getunique(struct file *file, unsigned int cmd,
return -EFAULT;

u = compat_alloc_user_space(sizeof(*u));
if (!access_ok(VERIFY_WRITE, u, sizeof(*u)))
if (!u)
return -EFAULT;
if (__put_user(uq32.unique_len, &u->unique_len)
|| __put_user((void __user *)(unsigned long)uq32.unique,
Expand Down Expand Up @@ -168,7 +168,7 @@ static int compat_drm_setunique(struct file *file, unsigned int cmd,
return -EFAULT;

u = compat_alloc_user_space(sizeof(*u));
if (!access_ok(VERIFY_WRITE, u, sizeof(*u)))
if (!u)
return -EFAULT;
if (__put_user(uq32.unique_len, &u->unique_len)
|| __put_user((void __user *)(unsigned long)uq32.unique,
Expand Down Expand Up @@ -200,7 +200,7 @@ static int compat_drm_getmap(struct file *file, unsigned int cmd,
return -EFAULT;

map = compat_alloc_user_space(sizeof(*map));
if (!access_ok(VERIFY_WRITE, map, sizeof(*map)))
if (!map)
return -EFAULT;
if (__put_user(idx, &map->offset))
return -EFAULT;
Expand Down Expand Up @@ -237,7 +237,7 @@ static int compat_drm_addmap(struct file *file, unsigned int cmd,
return -EFAULT;

map = compat_alloc_user_space(sizeof(*map));
if (!access_ok(VERIFY_WRITE, map, sizeof(*map)))
if (!map)
return -EFAULT;
if (__put_user(m32.offset, &map->offset)
|| __put_user(m32.size, &map->size)
Expand Down Expand Up @@ -277,7 +277,7 @@ static int compat_drm_rmmap(struct file *file, unsigned int cmd,
return -EFAULT;

map = compat_alloc_user_space(sizeof(*map));
if (!access_ok(VERIFY_WRITE, map, sizeof(*map)))
if (!map)
return -EFAULT;
if (__put_user((void *)(unsigned long)handle, &map->handle))
return -EFAULT;
Expand Down Expand Up @@ -306,7 +306,7 @@ static int compat_drm_getclient(struct file *file, unsigned int cmd,
return -EFAULT;

client = compat_alloc_user_space(sizeof(*client));
if (!access_ok(VERIFY_WRITE, client, sizeof(*client)))
if (!client)
return -EFAULT;
if (__put_user(idx, &client->idx))
return -EFAULT;
Expand Down Expand Up @@ -345,7 +345,7 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd,
int i, err;

stats = compat_alloc_user_space(sizeof(*stats));
if (!access_ok(VERIFY_WRITE, stats, sizeof(*stats)))
if (!stats)
return -EFAULT;

err = drm_ioctl(file, DRM_IOCTL_GET_STATS, (unsigned long)stats);
Expand Down Expand Up @@ -382,8 +382,7 @@ static int compat_drm_addbufs(struct file *file, unsigned int cmd,
unsigned long agp_start;

buf = compat_alloc_user_space(sizeof(*buf));
if (!access_ok(VERIFY_WRITE, buf, sizeof(*buf))
|| !access_ok(VERIFY_WRITE, argp, sizeof(*argp)))
if (!buf || !access_ok(VERIFY_WRITE, argp, sizeof(*argp)))
return -EFAULT;

if (__copy_in_user(buf, argp, offsetof(drm_buf_desc32_t, agp_start))
Expand Down Expand Up @@ -414,7 +413,7 @@ static int compat_drm_markbufs(struct file *file, unsigned int cmd,
return -EFAULT;

buf = compat_alloc_user_space(sizeof(*buf));
if (!access_ok(VERIFY_WRITE, buf, sizeof(*buf)))
if (!buf)
return -EFAULT;

if (__put_user(b32.size, &buf->size)
Expand Down Expand Up @@ -455,7 +454,7 @@ static int compat_drm_infobufs(struct file *file, unsigned int cmd,

nbytes = sizeof(*request) + count * sizeof(struct drm_buf_desc);
request = compat_alloc_user_space(nbytes);
if (!access_ok(VERIFY_WRITE, request, nbytes))
if (!request)
return -EFAULT;
list = (struct drm_buf_desc *) (request + 1);

Expand Down Expand Up @@ -516,7 +515,7 @@ static int compat_drm_mapbufs(struct file *file, unsigned int cmd,
return -EINVAL;
nbytes = sizeof(*request) + count * sizeof(struct drm_buf_pub);
request = compat_alloc_user_space(nbytes);
if (!access_ok(VERIFY_WRITE, request, nbytes))
if (!request)
return -EFAULT;
list = (struct drm_buf_pub *) (request + 1);

Expand Down Expand Up @@ -563,7 +562,7 @@ static int compat_drm_freebufs(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request)))
if (!request)
return -EFAULT;
if (__put_user(req32.count, &request->count)
|| __put_user((int __user *)(unsigned long)req32.list,
Expand All @@ -589,7 +588,7 @@ static int compat_drm_setsareactx(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request)))
if (!request)
return -EFAULT;
if (__put_user(req32.ctx_id, &request->ctx_id)
|| __put_user((void *)(unsigned long)req32.handle,
Expand All @@ -613,7 +612,7 @@ static int compat_drm_getsareactx(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request)))
if (!request)
return -EFAULT;
if (__put_user(ctx_id, &request->ctx_id))
return -EFAULT;
Expand Down Expand Up @@ -646,7 +645,7 @@ static int compat_drm_resctx(struct file *file, unsigned int cmd,
return -EFAULT;

res = compat_alloc_user_space(sizeof(*res));
if (!access_ok(VERIFY_WRITE, res, sizeof(*res)))
if (!res)
return -EFAULT;
if (__put_user(res32.count, &res->count)
|| __put_user((struct drm_ctx __user *) (unsigned long)res32.contexts,
Expand Down Expand Up @@ -689,7 +688,7 @@ static int compat_drm_dma(struct file *file, unsigned int cmd,
return -EFAULT;

d = compat_alloc_user_space(sizeof(*d));
if (!access_ok(VERIFY_WRITE, d, sizeof(*d)))
if (!d)
return -EFAULT;

if (__put_user(d32.context, &d->context)
Expand Down Expand Up @@ -764,7 +763,7 @@ static int compat_drm_agp_info(struct file *file, unsigned int cmd,
int err;

info = compat_alloc_user_space(sizeof(*info));
if (!access_ok(VERIFY_WRITE, info, sizeof(*info)))
if (!info)
return -EFAULT;

err = drm_ioctl(file, DRM_IOCTL_AGP_INFO, (unsigned long)info);
Expand Down Expand Up @@ -807,7 +806,7 @@ static int compat_drm_agp_alloc(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
if (!request
|| __put_user(req32.size, &request->size)
|| __put_user(req32.type, &request->type))
return -EFAULT;
Expand All @@ -834,7 +833,7 @@ static int compat_drm_agp_free(struct file *file, unsigned int cmd,
u32 handle;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
if (!request
|| get_user(handle, &argp->handle)
|| __put_user(handle, &request->handle))
return -EFAULT;
Expand All @@ -858,7 +857,7 @@ static int compat_drm_agp_bind(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
if (!request
|| __put_user(req32.handle, &request->handle)
|| __put_user(req32.offset, &request->offset))
return -EFAULT;
Expand All @@ -874,7 +873,7 @@ static int compat_drm_agp_unbind(struct file *file, unsigned int cmd,
u32 handle;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
if (!request
|| get_user(handle, &argp->handle)
|| __put_user(handle, &request->handle))
return -EFAULT;
Expand All @@ -897,8 +896,7 @@ static int compat_drm_sg_alloc(struct file *file, unsigned int cmd,
unsigned long x;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
|| !access_ok(VERIFY_WRITE, argp, sizeof(*argp))
if (!request || !access_ok(VERIFY_WRITE, argp, sizeof(*argp))
|| __get_user(x, &argp->size)
|| __put_user(x, &request->size))
return -EFAULT;
Expand All @@ -923,8 +921,7 @@ static int compat_drm_sg_free(struct file *file, unsigned int cmd,
unsigned long x;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
|| !access_ok(VERIFY_WRITE, argp, sizeof(*argp))
if (!request || !access_ok(VERIFY_WRITE, argp, sizeof(*argp))
|| __get_user(x, &argp->handle)
|| __put_user(x << PAGE_SHIFT, &request->handle))
return -EFAULT;
Expand Down Expand Up @@ -952,7 +949,7 @@ static int compat_drm_update_draw(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request)) ||
if (!request ||
__put_user(update32.handle, &request->handle) ||
__put_user(update32.type, &request->type) ||
__put_user(update32.num, &request->num) ||
Expand Down Expand Up @@ -994,7 +991,7 @@ static int compat_drm_wait_vblank(struct file *file, unsigned int cmd,
return -EFAULT;

request = compat_alloc_user_space(sizeof(*request));
if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
if (!request
|| __put_user(req32.request.type, &request->request.type)
|| __put_user(req32.request.sequence, &request->request.sequence)
|| __put_user(req32.request.signal, &request->request.signal))
Expand Down

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